SBS Isometrics for performance

Isometrics
for Performance
Max Schmarzo & Matt Van Dyke
Isometrics
for Performance
Max Schmarzo
&
Matt Van Dyke
Table of Contents
Preface…………………………………………………………………………………………i
The Facilitation of Isometric Training….……………………………………....ii
About the Authors………………………………………………………………………iii
Section 1
What are Isometrics?...................................................…………………1
Section 2
Types of Isometric Contractions………………………………………………...14
Section 3
Physiology of Isometric Training……….………………………….…………...30
Section 4
Adaptations due to Isometric Training..……………….……………………37
Section 5
The Implementation of Isometric Training “How To”…………………53
Section 6
Applied Isometric Programming….………………………………………….…76
Section 7
The Importance of Isometric Strength in the SSC………………………82
Preface
The implementation of isometric training principles has become an increasingly popular
method utilized recently by performance coaches at all levels. Although the true
implementation of an isometric protocol is basic, with the requirements of no muscle
length change, the adaptations realized through different isometric training varies
drastically. This book will provide examples of each of the different available isometric
training options, cover the adaptations of each method, while also demonstrating each
of these training methods within a program. This manual, similar to the previous Power
Manual, continues to avoid the cookie-cutter, or “one-size fits all” approach, and
instead places focus on the concepts and theories of isometric training in order to
maximize its utilization. Practical examples will be provided throughout this manual as
well to ensure every coach has the ability to implement the described concepts with
success. The ultimate goal of our writing continues to be to provide every coach with
the knowledge and understanding to implement these training principles in the most
efficient, and effective manner possible for their athlete population.
i
The Facilitation of Isometric Training
It is imperative to note that this manual describes the most useful, available, and up-todate methods to improve athletic performance through the utilization of isometric
training protocols. However, as clearly demonstrated throughout this manual, the
available adaptations are far-reaching and thus, the implementation of isometric
training becomes increasingly complicated in programming. The adaptations required to
improve this aspect of performance involve multiple cellular, structural, and
neurological changes within the body. In order to optimize each of these individual
adaptations, different training methods must be implemented.
ii
About the Authors
Max Schmarzo
Max Schmarzo is an NSCA Certified Strength and Conditioning Coach (CSCS) and NATA Certified
Athletic Trainer (ATC). He received his MS in Kinesiology from Iowa State University, where he
led investigative research on relationship between the force-velocity profile of the squat and
vertical jump height.
Prior to entering graduate school, Max played four years of NCAA Division III basketball. As an
undergrad, he doubled majored in athletic training and strength and conditioning.
Throughout his undergraduate and graduate schooling, he was able to complete several
internships, including working under Chris Doyle at the University of Iowa, Josh Beauregard at
Iowa State University and Donald Chu at Athercare in Dublin, California.
Max also writes professionally for his website and social media (Instagram),
http://www.strongbyscience.net/ and @Strong_by_Science, respectively.
Matt Van Dyke
Matt Van Dyke is the Associate Director of Sports Performance at the University of Denver
where he is responsible for designing and implementing performance training for men’s
lacrosse, alpine ski, volleyball, and swimming.
Prior to his position with Denver, Matt was the Assistant Director of Strength and Conditioning
for Olympic Sports at the University of Minnesota. Matt completed his Graduate Assistantship at
St. Cloud State University, where he earned his Masters of Science in exercise physiology and
nutrition in 2015.
Matt completed internships with Iowa State and the University of Minnesota under Yancy
McKnight and Cal Dietz, respectively.
Matt most recently released the Triphasic Lacrosse Training Manual, presented at the 2015
CSCCa National Conference on Advanced Triphasic Training Methods, while also writing for his
professional website vandykestrength.com.
Matt is certified by the CSCCa (SCCC). He earned his Bachelor’s Degree in exercise science from
Iowa State University in 2012.
iii
Max & Matt
This book is the second produced by the combined efforts of both Max & Matt. Their first book,
Applied Principles of Optimal Power, provided insight to develop power within athletes in an
efficient science based manner. To see this manual, click here.
iv
Section 1
WHAT ARE ISOMETRICS?
1
An isometric contraction of the muscle occurs when the tension developed within the muscle is
equal to the external load imposed upon the muscle. From an external appearance, an
isometric contraction of a muscle may look as if the limb as to which the muscle produces
movement is in a static position. However, despite the external lack of movement, inside the
muscle there are small, micro contractions of the muscle fibers. Thus an isometric contraction
may be highlighted by its external appearance of a static position, but should not be labeled as
a lack of or constant state of contraction, as the muscle fiber components are still active to
produce force.
Like all muscular actions in sport, isometric actions occur in conjunction with other dynamic
actions. For example, in running, the erector muscles of the back might be contracting
isometrically to maintain the upright posture required while the arms and legs are working
dynamically to produce locomotion. This isometric “stability” is required to some extent in
every movement completed in life, without it, movement efficiency will likely be drastically
reduced.
Isometric muscle actions are not only utilized in stabilization, but also in the rapid transfer of
energy within a single musculo-tendon structure. This occurs commonly in the stretchshortening cycle (SSC) where energy is transferred in a harmonious manner throughout the
muscle. During the SSC, the muscle goes from a lengthening (eccentric) muscle action to a rapid
shortening (concentric) muscle action. The isometric contraction phase is wedged between
these two and, in a highly trained athlete, will only be utilized for a brief moment in time.
However, its importance in this process cannot be overstated. Isometric strength plays a critical
role in executing movement in a synchronized, efficient, and powerful manner as force is
transferred through these muscle action phases. Together, the isometric (no length change),
eccentric (lengthening), and concentric (shortening) muscle actions are utilized within the body
in multiple fashions in order to orchestrate human movement.
2
The SSC seems to be understood to some extent within the sport performance realm, but
taking even a more simplistic approach to force production, it can be stated that isometrics are
required at all times prior to the completion of a concentric muscle action. Ultimately, in order
for any limb to complete a motion, the acting muscle must first generate enough force
throughout the musculo-tendon unit to overcome the forces acting against it. These resisting
forces range from a 700 lb deadlift, to picking up the fork in front of you on your table, to even
simply raising your arm in front of you. Although the forces required to complete each of these
movements are vastly different, as the majority of people are not able to produce force levels
to lift a 700 lb object, there is still some level of force required to complete each of these
actions prior to movement ever actually occurring.
During the initial portions of tension development, when the limb is not in a state of motion
(shortening or lengthening contraction), the muscle is acting in an isometric state. Only when
isometric tension has been developed to the point that the force produced by the muscle is
greater than the external load acting on it (700 lb barbell, 0.2 lb fork, or even simply gravity on
your arm) will movement in a concentric action occur.
This concept is demonstrated in figure 1.1. As the force required to complete a movement
increases, the time required to achieve this level increases as well. This can be seen in the
difference of time between the execution of the 700 lb deadlift and the picking up of the fork. It
should also be apparent that there are many individuals (us included) that are not capable of
completing a 700 lb deadlift. This means they are ultimately not capable of creating the force
requirement of this extreme exercise. Both the time required to achieve different force levels,
along with the force production abilities (minimal, moderate, and maximal) will be individual
for each athlete. However, with appropriate training, as laid out in this book, many athletes will
not only see increases in their “maximal force output” abilities, but also potential decreases in
the amount of time to achieve these high-level force outputs.
3
Figure 1.1: Regardless of the executed movement, isometric force is required. This figure (not to scale)
represents the “ramp-up” of force required to complete three different tasks. It is important to note
that both of the axes (force production and time required) will be altered through different training
programs.
The deadlift example, as it requires high-force output in order to be completed with a high
relative load, is a movement in which the “ramp-up” of isometric force can be easily viewed. In
the earliest phases of this exercise there is noticeable tension developed throughout the
athlete’s body, yet the bar has not moved. It is not until enough tension is developed that the
athlete can then perform the concentric portion of the lift. It is during the delay of noticeable
tension and movement where the isometric force is being developed. This high level of tension
created can also be viewed in many of the Pre-Activation Potentiation (PAP) exercises that were
provided in the previously released Power Manual. These exercises, particularly the “pin pull”
style also create maximal or near maximal tensions while no movement occurs. Again, this
simply re-iterates the isometric force required in every concentric contraction. A “ramp-up” of
4
isometric force is needed with force exceeding the external resistance in order for “movement”
to occur. No one wants to be stuck in the ground with a heavy deadlift attempt, let alone not be
capable of picking up the fork on their table.
Clearly isometric contractions should not be underestimated in their importance in training and
performance. Different types of isometrics, the physiology, potential adaptations, along with
different training applications to match the desired adaptations will all be covered in much
greater detail throughout the upcoming sections of this book.
External versus Internal Appearance
One issue with judging movement solely through the human eye is that external appearance of
the body may not always indicate the internal muscular contraction being completed. This
becomes particularly important in regards to the isometric muscle action, as no “movement”
occurs. For example, during plyometric activities, coaches are able to see the large amounts of
eccentric and concentric muscular actions occurring, with little to zero isometric actions visible.
However, despite minimal external viewing of the isometric phase during dynamic movements,
based on the previous paragraphs we all know and understand this contraction phase occurs
with every ground contact completed during the plyometric training.
As ground contact occurs during plyometric exercises, the muscle is loaded eccentrically as the
musculo-tendon unit “ramps-up” in force production. As the force produced continues to
increase, the lengthening of the unit is slowed and eventually halted. It is at this exact moment,
where the force production is equivalent to the ground reaction force of landing (external) that
the isometric contraction occurs. As this internal force continues to increase to become greater
than the external force, the concentric muscle action is achieved and the athlete moves
explosively into their subsequent movement. This is a brief introduction to the SSC, but it is
crucial all coaches understand this application as we continue to dive deeper into the
importance of the isometric muscle contraction.
5
Whether the isometric contraction occurs in a high load, velocity, or a combination of the two,
there are always specific steps that occur within the body in order to complete any contraction.
These contraction steps are listed below in the order of their occurrence.
1. Muscle contraction is initiated by a signal from the alpha motor neuron
2. Action potential releases acetylcholine
3. Acetylcholine binds to motor end plate, releasing sodium, which enters the cell and
depolarizes the muscle fiber
4. This depolarization reaches the T-tubules, which release stored calcium from the
sarcoplasmic reticulum into intracellular space
5. Calcium binds with troponin-C on the actin filament, moving tropomyosin and exposing
actin’s binding sites
6. Myosin heads attach to the binding site now exposed on actin filaments
7. Myosin heads tilt, locking the actin filament in place and generating tension in the active
muscle fibers
8. Myosin heads detach from actin when ATP binds to globular head
9. ATP is split by ATPase into ADP and an inorganic phosphate, releasing energy
10. Energy release re-cocks the globular head of the myosin filament, priming it for another
attachment to actin
As stated above, these steps occur in every muscular contraction within the human body. This
remains true even when no movement occurs during an isometric contraction.
6
Isometrics in Dynamic Movement
Based on the example above, each of these three muscle action phases occur in EVERY dynamic
movement. Again, regardless of the exercise/movement being completed, there is always a
coupling of eccentric to concentric contraction with an isometric occurring in the middle as the
muscle fibers change their direction.
Eccentric – Isometric – Concentric
Another simple example of these muscle actions can be viewed in the execution of a
countermovement jump. Below are two examples of how these three muscle action phases
work in harmony to transfer energy throughout the execution of a jump. We are going to “geek
out” according to some, over these next few paragraphs explaining some of the forces being
experienced by this athlete throughout a countermovement jump. This will be explained in the
simplest manner we know how, with the hopes that by the end of this section all coaches
understand the importance of the isometric muscle action in regards to dynamic movement
and the importance it plays in determining elite level performance.
7
Figure 1.2: A “lower level athlete” is demonstrated in this countermovement jump. This can be seen in
the amount of time required to complete each of the three muscle action phases.
Figure 1.3: An “advanced athlete”, at least relative to the first athlete, is demonstrated in this
countermovement jump. This can be seen in the reduced time required to maneuver through each of
the three muscle action phases as the jump is executed.
Again, these two figures demonstrate the completion of a countermovement jump while being
measured on a force plate. The top figure (figure 1.2) is a lower level athlete, while the second
(figure 1.3) is an advanced athlete in regards to their SSC and force production capabilities. We
8
understand this technology is not available to every coach at this time. However, by
individualizing each moment of force production, this example can be realized in a much clearer
fashion by all. Each arrow depicted will be covered individually below.
The green arrow shows the beginning of the countermovement jump. The force plate has been
“zeroed-out” with the athlete standing on it to negate any force provided by the athlete’s mass
due to gravity. Ultimately this simplifies the data management process for simpler graphing and
viewing. We recognize the athlete must be producing force to some extent to reverse the
effects of gravity, but are negating those at this time. Coaches should note the negative slope
that occurs. This represents the athlete “falling” faster than the pull of gravity. Ultimately
meaning the athlete is “pulling” themselves into the desired position or “folding” themselves
up by actively flexing at the hip. All athletes complete this during countermovement, but to a
different extent depending on many factors such as orthopedic function and previous training.
The most powerful/explosive athletes will be capable of “pulling into position” at a higher rate
than others, while still being capable of rapidly reversing those forces produced. This concept
will be further discussed in a section later in this book.
The red arrow demonstrates the point at which the eccentric muscle action phase begins for
the hip extensors. Up to this point the athlete has been “free-falling”, to oversimplify, which
has caused an increased velocity in the downwards direction (due to gravity). At this point the
athlete must now produce force in order to prevent them from being “folded up” by their
accelerating body in the downward direction. This “folding up” can be seen if an athlete were
to be placed upon a box of an excessive height and asked to complete a depth drop jump. As
the athlete attempts to create force in the opposite direction upon landing, if they are unable
to produce the required force they will end up passing through this “folded up” state as they
crumble to the ground. We do not suggest testing this to coaches as this is not an appropriate
or safe method of training.
9
Again, it is at this time the hip extensors begin to “ramp-up” their force production to
decelerate the athlete’s body. However, as the net force is not equal to zero, which we know is
a requirement for an isometric contraction to occur, the muscle is being actively lengthened, or
completing an eccentric muscle action. This phase of lengthening will continue to occur until
the sum of positive forces (green shaded area) is equal to the sum of the negative forces (red
shaded area), ultimately resulting in a net force of zero.
The blue arrow depicts the isometric contraction, FINALLY! This, at least when first introduced,
seems to be the most commonly confused arrow. Many coaches want to place this blue arrow
at the point where force is depicted at zero (roughly “53” on the “Time” x-axis in figure 1.2).
Although this thinking of “zero” force is correct, we must ensure it is the net force of zero. In
order to calculate the exact moment of the isometric contraction, or when net force is equal to
zero, calculations are required to some extent so please bear with us. In this example, a
simplistic approach is applied to allow ease of calculation. With the understanding that net
force must be equivalent to zero, we must utilize the “negative” forces experienced in this
movement and compare them to the “positive” forces in order to determine this exact
moment. The “negative” forces are any force measured that is below zero, in this case, the red
shaded area. The “positive” forces begin immediately after the force value of zero and continue
throughout the remainder of this movement. Although positive forces are being accumulated
with each individual moment in time, their sum has not reached the sum of the negative
impulses, meaning the athlete is still experiencing an eccentric contraction.
Only when the sum of the negative forces is equivalent to the sum of all positive forces is the
net force zero. Meaning the exact moment of an isometric contraction can be easily calculated
when exact force impulses are available for a coach. At this time however, we are merely
providing the concept to continue to reinforce the ability to produce force in an isometric
manner. If an athlete can “ramp-up” their force in a more rapid manner, particularly in the
moments leading up to, and just after the isometric contraction, they will be capable of
10
reversing the direction of their muscle (from lengthening to shortening), and thus express more
explosive power.
Finally the black arrow displays the moment the muscle begins to contract in a concentric
fashion. This concentric muscle action begins occurring immediately following the isometric
moment as the sum of the “positive” forces are now greater than the sum of the “negative”
forces. As long as the athlete continues to produce force in a “positive” manner, they will
continue to produce force in a concentric manner until they achieve their structurally available
range of motion.
With this being a countermovement jump, the athlete begins traveling downwards (green
arrow), begins to “ramp-up” the force placed into the ground to begin decelerating their
downward force (red arrow), they eventually (hopefully) produce enough force to come to a
complete, although brief, halt at their bottom position (blue arrow), before immediately
beginning their propulsion upwards (black arrow).
The differences between the lower level, and advanced athlete quickly become clear in these
two examples shown. The lower level athlete is not able to create as much “negative” force as
rapidly as their body understands they will not be capable of overcoming this produced force in
an efficient manner. On the other hand, the advanced athlete, relative to the lower level
athlete, is much more capable of rapidly “pulling down” into the optimal hip flexed position.
This can be achieved as the athlete is able to “ramp up” their force rapidly, even when this large
negative force is applied.
Clearly the differences in time required to achieve each of the muscle action phases also plays a
role in performance. The lower level athlete requires extensive time to complete the jump
when compared to the advanced athlete. This will likely provide a competitive advantage to the
advanced athlete on the field when racing to get into an appropriate position for receiving a
pass, for example.
11
The differences between muscle synchronization can also be seen through the slope of the
force production curve. In the lower level athlete, the constant shifting, almost “wave-like”
pattern of force production provides a coach with information on specific weak points within
the jump. These weaknesses could be due to a multitude of factors ranging from simple force
production availability, to transfer of force, all the way to structural issues that may hinder
force production through a specific joint. Even in the advanced athlete, there is still a time in
which the force production dips significantly “negative”. When a coach sees this and
understands where the athlete is “bleeding power”, through the use of a motion capture
system, specific methods can be implemented, particularly with the advanced athlete, to
increase the strength, transfer of energy, or other adaptations/methods as they feel
appropriate.
Ultimately the steeper and smoother the slope, the more rapid the force production (either
positive or negative) and efficiency of its production. This steep, smooth slope should remain a
goal of all performance coaches in the constant pursuit of optimal performance. It is important
to note that different competition events may require an athlete to achieve a different slope in
competition. That being said the understanding of the event must be critically considered.
Although we understand force plates and a motion capture system are not available to all
coaches, the ability to understand these differences can play a pivotal role in the “coach’s eye”
on the floor as programs are progressed. As these inappropriate “ramp-up” or synchronization
aspects occur, coaches will continue to improve the methods utilized to address and alter them,
with the ultimate goal of maximizing available performance.
The isometric contraction in this dynamic situation only occurs for a brief moment, literally as
one “dot” on this force curve example, but again its importance cannot be overlooked. If an
athlete can “ramp-up” their force in a more rapid manner, as seen in the second athlete’s jump,
12
they will be capable of reversing the direction of their muscle (from lengthening to shortening),
and thus express more explosive power.
Ultimately, during any dynamic movement, there will be an eccentric phase where force is less
than the load imposed upon it. There will be an isometric phase where torque (force) is equal
to the load imposed upon it. Then there will be a concentric phase where the torque (force) is
greater than the load imposed upon it. With recent debate in literature, some experts have
theorized that isometric muscle actions may even play a larger role in exercises than first
expected. It is believed by some, that during high-speed, small amplitude movements the
tendon will deform during the lowering “eccentric” portion, while the muscle will actually
maintain its muscle length and contract isometrically. This in turn will allow for more force to
be developed by the muscle and reduce the cost of energy expenditure and total muscular
work. Thus, the eccentric muscle action my play less of a role, while the ability to rapidly
developed isometric force may play a more prominent role in these high power movements.
13
Section 2
TYPES OF ISOMETRIC
CONTRACTIONS
14
Types of Isometrics
Based on the many different circumstances that isometrics are utilized, in both everyday
movement and in athletics, it is only logical that it be understood there are many different
types of isometrics. Yes, the net torque being equal to zero remains a requirement of an
isometric contraction, but the manner in which this net force is achieved and then sustained
can vary drastically. Similar to the other two muscle actions (eccentric and concentric, the
external load imposed upon the muscle, the amount of momentum required to be changed, the
time allowed to perform the movement and the external environment all impact the type of
isometric contraction that may occur. This upcoming section is designed to aid coaches in
understanding the different types of isometrics that occur.
15
Figure 2.1: This branch system demonstrates different methods in which isometric contractions can be
implemented. Based on the continuum of both isolation/complex and muscle length, it quickly becomes
clear how rapidly the number of available options in which to implement isometric training techniques
expands.
16
Complex versus Isolation
Isometrics can be performed in one of two styles, either in isolation or in a complex manner.
From these two styles, different types of isometrics can be performed, as demonstrated in the
rapid branching in figure 2.1. It is important to note, that performing a true “isolation” of any
muscle is near impossible in any dynamic setting, however, for the sake of simplicity, any time a
single muscle or joint is being targeted, it will be considered isolation.
Complex isometrics involve the contraction of many different muscles acting upon many
different joints. For example, when performing an isometric squat, not only are the knee
extensors contracting, but so are the hips, erectors, shoulders and feet. However, when
performing an isolation knee extension, for the most part, only the knee extensors will be
contracting. Like all aspects of human movement, complex and isolation work on a continuum,
with pure isolation being on one end and complex being on the other
Figure 2.2: The isolation to complex continuum of isometric training. Any isometric contraction
completed can be placed somewhere along this line. The goals of the training program will ultimately
determine where and when each type of isometric is completed.
Before going any further, it is important to point out some innate characteristics regarding the
differences between isolation and complex isometrics. The more complex an isometric is, the
greater the number of active muscles. Thus, one can assume that the further to the right the
isometric falls on the continuum, the greater the metabolic and neurological stress. For this
reason, a coach should not assume the lack of dynamic movement means isometrics are less
fatiguing. In fact, it is quite possible the opposite may be true for a given exercise. An isometric
contraction requires continuous neural output to a specific target group of muscles for a time
17
that is typically longer than that of the same dynamic movement. Thus, the stress of the
dynamic movement may be greater than one may assume from purely an external analysis,
particularly when a maximal effort is required for any period of time. An example of a complex
isometric can be seen in figure 2.3 below with a demonstration of a split squat.
Figure 2.3: Example of a complex exercise: Isometric split squats targets not only the quadriceps, but
glutes, erector spinae, gastroc complex, and more.
18
Isometrics and Muscle Length
Due to the innate static character of isometrics (no changes in joint angles), the muscle length
at which the isometric is performed will have an influence on the adaptations. These specific
adaptations will be touched upon in the later sections. However, similar to the complex versus
isolation continuum, muscle length will fall on a continuum as well. Isometrics can be
performed at any muscle length available structurally to an athlete, from a long-length to shortlength position. This being said, each athlete’s continuum will vary based on their individual
ability to achieve a muscle length. For example, a gymnast’s continuum will typically be much
larger than a basketball player simply due to the requirements of their respective sport.
Figure 2.4: The muscle length continuum. Isometric training can be applied anywhere along this
continuum. The understanding of the competition demands becomes important here as the adaptations
achieved are specific to the muscle lengths in which the isometric training is applied.
This continuum is easier to analyze when the isometric that is being performed is an isolationisometric, because only one muscle is being targeted. However, when the isometric exercise
becomes more complex, different muscles will be receiving stress at different lengths. For this
reason, it is imperative that the exact reason why the isometric is being performed is
understood and the appropriate stimulus to achieve the respective goal is implemented.
19
Figure 2.5: Long muscle length (left) and short muscle length (right) isometric bicep curl.
Yielding versus Overcoming Isometrics
Not only will the duration and magnitude be different isometric training protocols, but also the
end goal of the isometric will also vary. These multiple goals include the holding of the
prescribed position, and the overcoming of the external resistance force. These different types
of isometrics include yielding and overcoming contractions, respectively.
Yielding contractions occur in an attempt to hold a position. This contraction type is normally
completed in a sub-maximal effort for an extended period of time while an athlete “’fights” an
20
eccentric contraction. This yielding isometric contraction typically is associated more with
postural muscles. This is due to the requirement of these muscles to constantly counteract the
forces of gravity acting on the body. Without the ability of these muscles to function for
extended periods of time, activities such as rucking for long distances, particularly with the use
of a heavier pack, would not be possible.
Referring back to the sprinting example in the opening section, the runner may be producing a
yielding isometric contraction through the spinal erectors to maintain optimal posture
throughout the race. These postural muscles of the sprinter are not attempting to overcome
any external resistance, as this would lead to undesired rotation of the torso; instead, they are
contracting to maintain the specific, desired position. Thus, the purpose of the static
contraction is to maintain force at a given level. The same “yielding” type of contraction can be
seen when looking at military personnel that are carrying equipment on their backs. Their
postural muscles are not trying to overcome the external resistance of the equipment, but
rather these muscles are contracting with just enough force to maintain an erect posture.
Efficiency of these muscles are key as it is their resistance to fatigue that has a high determinant
of success.
Isometric contractions can also be performed in an overcoming fashion. In this isometric type,
force is developed with the intent to overcome the external force. Typically, the execution of
this contraction type results in a maximal, or near-maximal magnitude and will culminate with a
concentric contraction. The countermovement jump, as described in the previous section, is a
simple example of this isometric type. As the athlete completes their jump, they rapidly “rampup” their force production with the goal of overcoming the “negative” force, ultimately leading
to the completion of a jump.
Returning to the sprinting example, simply because the erectors are performing a yielding
isometric contraction does not mean other muscles within the runner’s body cannot be
producing overcoming contractions. For example, when the sprinter’s foot makes contact with
21
the ground, the lower limb may be considered by many to be producing an isometric
contraction at a brief moment in time. However, the goal of this isometric contraction, unlike
the postural muscles, is to overcome the external force imposed and produce a powerful,
locomotive force. Thus, this type of isometric contraction can be labeled as overcoming, as the
muscle is attempting to produce as much force as possible to overcome the external load
imposed upon.
It is important to note that not all overcoming isometrics result in motion. For example,
someone can press against the supports of a power rack as hard as they can, in an overcoming
fashion with no movement occurring. The critical difference between yielding and overcoming
isometrics is the goal of the movement itself. The goal of yielding isometrics is to maintain
position, while the goal of overcoming isometric contractions is to produce movement. An
example of these two types of isometric training can be seen in figure 2.6. Both of these types
of isometric contractions are utilized frequently in training and performance.
22
Figure 2.6: Both types of isometrics (yielding and overcoming) can be applied with the same exercise to
achieve different results. This is represented above with both images showing an isometric squat with a
barbell. However, the left demonstrates a yielding isometric, while the right is shown as an overcoming
isometric.
Isometrics for Duration
Depending on the action being performed, the duration of the isometric contraction may vary
greatly. This is true even in training and athletics. Take into account the 700 lb deadlift
compared to the countermovement jump described in the previous section. During the 700 lb
deadlift the athlete is “ramping-up” force for an extended period of time, creating tension
through the bar. When there is finally enough force developed to overcome the external
23
resistance of the bar, the lift is successfully executed. On the other hand the isometric
contraction occurs for an extremely brief moment in time during the countermovement jump,
as it is sandwiched between the eccentric and concentric actions. Clearly these differences in
duration, lead to the requirement of labeling the isometric contractions experienced. These
labels should consider both the length of time at which the isometric action must be produced
for, the load placed on the athlete, and also the speed the action is completed at. Each of these
are demonstrated above in the deadlift vs. countermovement jump example.
Even in athletics, the isometric duration can also vary drastically. Although, the most common
isometric is found in a rapid occurrence, as seen in the SSC utilized in every dynamic movement,
long-duration isometrics are also utilized. For example, in a sport such as wrestling, two
athletes may “grapple” with each other in a static position for an extended period of time.
Although there is no “movement” in these grappling scenarios, athletes are still producing
submaximal forces to create a net force of zero. As one athlete pushes, or attempts to rotate
their opponent to a more advantageous position, the opposing athlete is pushing in the
opposite direction equally in order to prevent this position change. Again, this net force of zero
creates the stagnant contraction. Neither athlete may be producing maximal, or even nearmaximal forces. Instead, this is more of a cognitive game of chess, as each athlete attempts to
analyze the likelihood of success with their next potential maneuver. This scenario being
considered, wrestlers must be capable of sustaining a specific level of isometric contraction at a
magnitude (based on the strength of their opponent) that is not so overbearing that it hinders
cognitive processes. A similar situation occurs in football, when offensive linemen are required
to push against their opposition with equal, or hopefully greater force. This force production
allows blocks to be sustained for an extended period of time while protecting the quarterback.
Thus, there is a paramount of importance on being able to sustain an isometric contraction for
an extended period of time depending on the sport.
From the above examples, it is easy to see that being able to sustain an isometric contraction of
a specific magnitude for a certain duration of time can be critical for a successful performance
24
in athletics. The need for duration of isometric contraction varies widely from sport to sport.
For example, a sprinter may need to maintain an isometric contraction through the trunk to
remain erect for a single, ten second bout. Although this is a relatively short amount of time,
the magnitude of this contraction may exceed many other isometric contractions, not to
mention the multiple number of heats the successful sprinter will be required to compete in.
On the other end of the spectrum, a cyclist will need to produce a smaller magnitude of
isometric force to maintain their positioning throughout a race, but will be required to maintain
that contraction for an extended period of time. This can be seen in races such as the Tour de
France, which covers hundreds of miles throughout its multiple stages within the race. Thus,
the duration and magnitude are highly specific to the given sport, and must be trained for in
this specific manner.
Explosive Isometrics
Explosive isometrics are predicated not only on the magnitude of the force developed, but also
upon the velocity at which this magnitude is required. The speed of the executed movement
will dictate the speed at which an isometric contraction will need to occur. For example, when
pushing a car, or lifting the 700 lb barbell in the deadlift exercise described earlier, there is a
large amount of time to develop isometric force. Thus, the requirement for isometric force to
be rapidly built up may not play much of a role.
However, in the case of athletic movements, this time is almost always limited due to the
attempt of an athlete to complete the desired skill in the highest velocity available to them. If
one is not able to rapidly achieve the isometric force required within the brief amount of time
available, successful performance becomes much less likely. This can be seen in the example of
the countermovement jump described earlier. If the athlete in the countermovement jump
“ramps-up” their force in a slow manner, it will require greater time in order to achieve an
isometric contraction. This athlete will either have less time to produce force through their
concentric muscle action, as they required a longer “ramp-up” time, or will take longer in order
25
to execute the countermovement jump. In either case the athlete will demonstrate a significant
reduction in performance compared to their potential. This can be seen in the “lower level
athlete”, who is commonly described as “running in mud” as they lack the ability to produce
high-levels of force in the brief amount of time available due to the high velocities. The
opposite is seen in the athlete able to rapidly “ramp up” their isometric force production. This
athlete is capable of moving though each trained motion in a smooth, violent manner. Thus, the
athlete who can rapidly develop isometric force and therefore begin concentric contraction
sooner may be at an advantage from a physical performance standpoint.
Based on our understanding of all dynamic movements require the coupling of an isometric
contraction between the eccentric and concentric muscle actions, the ability to rapidly develop
isometric force is clearly of critical importance for the majority, if not all, team and field based
sports. In these situations it is ideal that the athlete be capable of producing high levels of force
rapidly in order to transfer through these three muscle action phases at the highest velocities
possible. Together, this high magnitude and speed of development would allow for a more
powerful concentric contraction. However, it is important to note that the speed at which an
isometric contraction occurs, or any muscular contraction for that matter, is independent of the
magnitude of the contraction. Thus, in an ideal situation the athlete will not only be able to
produce an isometric force rapidly, but also with a large magnitude. Together, this high
magnitude and speed of development would allow for a more powerful concentric contraction.
26
Figure 2.7: Explosive isometrics are typically done using overcoming isometrics. This is due to the fact
that producing force into an immovable object, such as the rack supports allow for a safe and rapid
buildup of tension. However, this does not mean certain types of plyometric movements, as seen in the
amortization phase, would not be included.
27
Isometrics and their role in Resisting Force
Isometrics, particularly those of the yielding nature, play an important role in resisting forces.
For example, all yielding isometric contractions are predicated on maintaining a position and
therefore resisting forces that try and move the body out of these positions. Thus, one could
argue that the ability to rapidly develop isometric force equal that which is being imposed on
the body play a critical role in reducing the likelihood of injuries.
In sport, the forces athletes encounter can rarely be predicted with a high level of accuracy.
This is simply due to the dynamic and open-ended nature of sports. For example, a basketball
player going up for a layup may be bumped by a defender on the other team who is trying to
prevent him from scoring. Thus, in order to avoid injury, the player attempting the layup must
rapidly contract with the required force in order to achieve a safe, isometric landing position. If
this athlete is not able to rapidly “ramp-up” the force required to achieve this stable landing,
they will likely end up in a poor position biomechanically that will likely increase the chances of
a catastrophic injury. At the same time, if the athlete going up for the layup is kinesthetically
proficient, they may be able to isometrically contract against the forces imposed by the other
player and successfully maintain postural alignment and score the basketball. Thus, the ability
to rapidly develop a yielding isometric may not only be critical for safety, but also performance.
Co-Contractions
During an isometric co-contraction, an agonist-antagonist pair will contract with the same
amount of torque around the same joint. Due to the equivalent torques being applied, a net
force of zero is achieved and thus, no motion will occur at the limb. This is true despite the fact
there will be an increase in torque around the joint compared to resting. Consider an intense
tug-o-war match. When two teams are equally pulling with high forces, yet the rope does not
move. The rope ultimately looks exactly as if the rope were laying on the ground and no one
was touching it, even though there is tremendous force being applied to it during the intense
28
match. It is this principle that is applied during co-contraction isometrics. The agonist,
antagonist pair are placed on opposite ends of the rope and during a co-contraction, they both
pull with equal force. Thus, there is no movement occurring in the rope, but there is a large
amount of tension developed through it. As long as the pairs contract with equal amounts of
force, the rope will remain taut and no motion will occur.
Co-contractions can be viewed often throughout bodybuilding shows. When a body builder
performs a bicep pose with their arms flexed at 90 degrees, both the bicep and tricep will
contract with equal torque around the elbow. Thus, the body builder can increase tension and
level of contraction of the muscle, in order to increase its size, while maintaining the static,
desired pose position.
An interesting aspect with co-contraction isometrics is that muscular actions are typically
predicated on producing force against an external load. However, with these types of isometric
contractions, the external load acting on the agonist is its antagonist counterpart. Thus both
muscles are producing force against each other and therefore, both will be stressed. However,
the joint angle will be dependent upon the amount of stress each muscle undergoes. This is due
to the fact that different joint angles, agonist and antagonist muscles will be at different
lengths, meaning the force producing capabilities of those muscles will be altered in each of
these positions.
Research indicates that co-contractions may be a useful form of training for developing
strength and EMG activity. As highlighted in a study performed by Zibidi and Colleagues
(2017)*, co-contraction training led to significant increases in strength and muscle EMG activity.
There may be more efficient training methods to target these specific desired adaptations,
however, the effectiveness of co-contraction training highlights diverse methods a coach has to
choose from when training an athlete.
* Zibidi, S., Zinoubi, B., Hammouda, O., Vandewalle, H., Serrau, V., Driss, T. Co-contraction training,
muscle explosive force and associated electromyography. The Journal of Sports Medicine and
Physical Fitness. 2017 Jun;57(6):725-733. doi: 10.23736/S0022-4707.
29
Section 3
PHYSIOLOGY OF ISOMETRIC
TRAINING
30
The acute physiological response to an isometric contraction is quite unique when compared to
either eccentric or concentric contractions (1). For this reason, some of the physiological
responses to sustained isometrics will be detailed. It is important to note that this is not an allencompassing list of acute responses to the utilization of isometric training. Coaches must also
understand that, as always, the intensity (magnitude), and duration of an isometric will alter
the response of the body. The alteration of any of these three factors will ultimately lead to a
different type of stress placed on the organism, and thus a different response. Coaches must
constantly consider the desired outcome of the training program and implement exercises to
achieve these adaptation goals.
Occlusion
The aspect that distinctly makes isometric contraction and the following physiological
responses unique, is the fact that a sustained contraction of leads to local muscular occlusion*
(depending on the literature, the amount of force needed for occulsion varies). The sustained
contraction constricts the surrounding circulatory pathways and traps the local blood within the
locally contracted muscle. From this localized occlusion, a cascade of unique physiological
events take place.
* When we state occlusion, we are referring to both arterial and venous occlusion, or
“full occlusion”. Within the muscle, it is possible to have just arterial, but not venous, occlusion,
depending on the contraction intensity.
Blood Pressure
Due to the localized occlusion, circulation is naturally hindered. Thus, the body’s sensory organs
recognize such an issue and in response, increase the output. Thus, blood pressure will rise and
a greater demanding will be placed on the cardiac response (2). Due to this increased blood
pressure, adaptations to the blood vessels as well as the cardiac system become possible. As
with any stress applied, it is important to ensure excessive stress is not applied to the
31
circulatory system. This stress level should be based on each individual’s abilities and their
previous training completed. By progressing safely, the likelihood of any rupturing of the blood
vessels will be decreased. Stress at an appropriate level is always critical for appropriate
training and adaptation.
Metabolic Accumulation
Due to the fact blood is restricted within the muscle completing the contraction, metabolite
clearance cannot occur to the same extent. Therefore, even at low percentages of voluntary
threshold, high order motor units will start be recruited as the lack of oxygen does not allow for
metabolites to be cleared and greater demand is placed on the glycolytic energy system (3). Just
as Henneman's size principles outlines, as greater local demand increases to maintain a specific
percentage of force, first the low-threshold fibers will be recruited, followed by higher order
fibers. Due to the lack of metabolite clearance, an increase in fiber recruitment can be seen, in
accordance with the Henman’s Ramp Principle.
Local Chemoreceptors
Within the muscle, there are local chemoreceptors that send afferent nerve impulses.
Essentially, these nerves report back what is going on to higher order systems. What happens
next is quite interesting. The nerve endings within the muscle will signal that ph is rapidly
decreased in the muscle, or the muscle is becoming more acidic. This is, in part, due to the
reduction in blood flow, and thus, the ability to clear out the produced, accumulated
metabolites. This decrease in pH, or increased acidity, leads to an increased breathing rate (4).
With oxygen and the aerobic system being responsible for the clearance of these produced, and
accumulated, metabolites the body is attempting to reduce this build up that it is being
informed of.
32
However, with this signal for increased breathing coming from a muscle completing an
isometric contraction, the increased intake of oxygen will not be capable of reaching the
specific muscle (complete occulusion). Thus, this breathing rate increase will not improve the
clearance of metabolites. This creates a unique situation in which the muscle enduring the
isometric contraction will remain in an acidic state, while the remainder of the body (the
muscles not experiencing the isometric stimulus) may enter an alkalosis state. This increase in
ph (alkalosis), also leads to a dysfunctional reduction in carbon dioxide, as the body is breathing
out this gas with every exhale (4). With carbon dioxide playing an important role in the
disassociation of oxygen from hemoglobin (Bohr effect), the body may further experience
reduced oxygen state. For this reason, it seems that maximally occluded sustained isometrics
would be quite difficult to maintain for an extended period of time. However, not all isometrics
lead to complete occlusion of the muscle, which explains why various intensities of isometrics
can be held for extended periods of time.
Contraction Released
When the isometric contraction has been completed for the programmed amount of time,
blood then flushes out of the local muscle, with the metabolites being cleared as well. The
nerve signals from the muscle are reduced, and breathing is rapidly normalized. The
accumulated metabolites enter nearby oxidative muscle fibers, where some are utilized as an
energy substrate, while others enter the circulatory system where other chemoreceptors exist
(4).
Systemic Chemoreceptors
The systemic chemoreceptors located throughout the circulatory system then experience a
rapid increase in metabolites as they are released from the now completed isometric muscle
contraction. These systemic chemoreceptors send nerve signals to the body, again requesting
for an increase in ventilation (breathing). This increased breathing rate will counteract the
33
waves of metabolites that were stored, and now released, from the muscle. This increased
ventilation may potentially cause a secondary level of excess carbon dioxide exhalation to
occur. However, this is entirely dependent upon the number of muscles utilized in an isometric
contraction (simple vs. complex) as well as the total amount of metabolite produced.
Return to baseline
The above breathing patterns highlight some of the unique qualities that are associated with
sustained isometrics. Breathing may increase during isometrics, reduce initially afterwards for
about 20-30 seconds and then spike again (4). For this reason, it is our hypothesis that the
recovery time required between sustained isometrics may be of a greater duration than
isotonic contractions, which do not present the same regulatory breathing patterns. Although
not in the spectrum of this book, we feel the appropriate training to “tolerate” high levels of
carbon dioxide should also be considered by coaches. As always though, this recovery time
required will be determined upon the level of intensity, velocity, as well as duration of the
isometric contraction. Each of these three will lead to a different outcome in terms of blood
flow occlusion as well as the number of metabolites produced and accumulated.
Catecholamine response
The catecholamine response from isometric exercises is quite different than that of concentric
and eccentric exercises. Again, the reasons for such differences likely are predicated on the
unique properties of a sustained isometric contraction described above.
When performing an isometric contraction, the catecholamine response is much larger when
compared to isotonic exercises, even when a greater total muscular demand is required of the
isotonic exercises. As highlighted in a study by Kozlowski and colleagues (5), a sustained
isometric contraction of a handgrip test at 30% of maximal voluntary contraction produced
34
nearly double the response in adrenaline in about a third of the time (5 minutes) when
compared to bicycle ergometer of test at 1200 kpm/min for 15 minutes.
“The pattern of plasma catecholamine response suggests that the haemodynamic reaction
during sustained voluntary static contraction could be related to the sympathetic activation
elicited by the reflex mechanism discussed above.” Kozlowski and colleagues (1973)
For this reason, sustained isometric contractions for long durations may provide a unique
training and hormonal stimulus when compared to other forms of muscular contraction.
35
SECTION 3 REFERENCES
1. D.A Jones and O.M. Rutherford. The effects of three different regimes and the nature of the
resultant changes. 2015;(August). doi:10.1113/jphysiol.1987.sp016721.
2. Chrysant, S. G. (2010), Current Evidence on the Hemodynamic and Blood Pressure Effects of
Isometric Exercise in Normotensive and Hypertensive Persons. The Journal of Clinical
Hypertension, 12: 721–726. doi:10.1111/j.1751-7176.2010.00328.x
3. Thomas, C., Perrey, S., Lambert, K., Hugon, G., Mornet, D., Mercier, J. Monocarboxylate
Transporters, Blood Lactate Removal After Supramaximal Exercise, And Fatigue Indexes In
Humans. Journal of applied Physiology, 98, 804-809. doi:10.1152/japplphysiol.01057.2004.
4. David C. Poole, Susan A Ward and Brian J Whipp. Control of blood-gas and acid-base status
during isometric exercise in humans. 1988
5. Brzezinska Z, Kowalski W. Plasma Catecholamines During Sustained Isometric Exercise.
1973:723-731.
36
Section 4
ADAPTATIONS DUE TO
ISOMETRIC TRAINING
37
With the wide range of isometric “types” listed in the previous section, it should come as no
surprise that there are multiple potential adaptations when implementing these training
methods. These adaptations range from structural, to changes realized by the energy systems,
and even changes in brain function. Again, each of these adaptations, along with the amount of
change realized by the athlete, are determined by the type and intensity (load and/or volume)
of the implemented exercises. The goal of this section is to provide coaches with the knowledge
and understanding of the physiological changes induced due to training with the use of
isometrics.
Potential Adaptations Realized due to Isometric Training
● Structural Adaptations
○ Hypertrophy, Fascicle length, Tendon stiffness, and Others
● Metabolic Adaptations
○ Increased tolerance of metabolic “build-up”
● Neural Adaptations
○ PAP, Brain “function”, Muscular coordination
Isometric training is able to induce several different structural adaptations to the athlete
completing the training. It is important to note that not all of these adaptations are unique to
isometric training. However, despite some of similar structural adaptations that may occur with
other forms of muscular activity, there are also a few unique changes that become more
pronounced with the utilization of isometric training and thus, will be pointed out in
conjunction with other, more general, adaptations.
38
Structural Adaptations
Hypertrophy and Increased Cross-Sectional Area
Isometric training is able to induce size changes in the muscle completing the contraction. This
should not come as a surprise as the muscle is required to match the level of force opposing it.
As the training load (intensity) or volume increases, the muscle is required to increase its force
output as well. Meaning that the hypertrophy/increased cross-sectional area adaptation will be
realized to a greater extent as the muscle is provided with a greater stimulus from training.
It is also important to continue to understand that these adaptations will be specific to the
length at which the muscle completes the training. It has been shown that these hypertrophic
adaptations may be more pronounced when the isometric contraction is completed in an
elongated muscular state, compared to a shortened state. Thus, the specific adaptive response
to isometrics may be dependent on the amount of stretch placed on the sarcomeres (1). Taking
this into account, it is highly likely the shortened and lengthened muscle positions, when
trained in an isometric fashion, may induce different types of neurological and structural
adaptations.
Fascicle length
Isometric training has the ability to not only induce hypertrophic responses, but also induce
changes in fascicle length. It was found that when performing isometric training in both
lengthened and shortened muscle positions, fascicle length of the muscle was increased (1).
Although strength improvements may be specific to the muscle lengths at which the isometric
contraction is completed, specific structural remodeling does not appear to be specific to this
length at which the muscle tissue is stressed isometrically.
39
Changes in fascile length are of importance for not only perfroamnce, as indicator by a
correlative indictor of sprint time (2,3) but also for rehabilitation and injury prevention (4). It has
been noted that logne rhamstring fascile lengths have been associated with a reduced risk of
hamstring injuries.
Tendon stiffness
Isometrics have been well documented to improve tendon stiffness (5-7). However, there is
typically a minimal increase in the tendon size. Thus, these adaptations are typically attributed
to architectural realignment within the fibers in the tendon, as opposed to increases in
hypertrophic response (5). It is this adaptation, along with the force producing capability of the
muscle that plays a pivotal role in the production of force through the SSC and its efficiency.
The adaptation of tendon stiffness has been shown to increase with the length of time the
isometric contraction is held (5). Thus, specific adaptations may be not only be based upon the
strain, or the intensity placed on the tendon, but also time under tension dependent. This could
explain why endurance running on low level athletes could be a positive stimulus for tendon
adaptation, as the countless number of strides increases the total duration of time the
musculo-tendon unit experiences an isometric contraction (8). However, this is not to say
intensity does not play a role as well. The high levels of stiffness in sprinters compared to
endurance runners may highlight the specific intensity dependent adaptations that occur with
high ground reaction forces, such as sprinting. Thus, a stiffer tendon serves to rapidly transfer
force through the SSC and can aid in efficient and powerful energy transfer, a critical skill in
both distance running as well as sprinting.
This concept of efficient and powerful transfer of energy through the SSC will be discussed in
greater detail later in the text. However, it should be noted now that sprinting, along with the
majority of competitive events, is a multi-faceted aspect in regards to performance. Although
important for the transfer through the SSC, tendon stiffness is not the only factor involved in
40
sprinting and running. This being realized, a sprinter with “less stiff” tendons may still be
capable of competing at a high level. However, if they are not capable of rapidly reversing the
high ground reaction forces required, they will still be competing at a state that is less than
optimal for them. For this reason the training of tendons to handle the magnitude of the
required forces in competition must be addressed in programming.
This requirement is realized in again, comparing the distance runner’s tendons to the sprinter’s
tendons. With both strain, magnitude, or intensity, as well as time under tension being factors
for increased tendon stiffness, each of these methods of locomotion are likely to produce
adaptations. However, the subtle difference between these two methods of achieving this
tendon change can be seen quickly when the distance runner is required to sprint. As the
magnitude of force traveling through the foot increases (as the runner increases velocity), the
tendon may not be capable of maintaining its “stiffness”. This is because the training
adaptation realized by the tendon in the distance runner is due to the repetitive exposure,
rather than that of high magnitude. Although the tendon may display increased “stiffness”
through each of these methods (strain as well as time under tension) it is imperative coaches
continue to realize that in order for the tendon to function at the highest level, it must be
trained to handle the high strain, or high time under tension, according to the requirements of
the competitive event.
These are merely two aspects that must be considered and understood as coaches implement
“specific” means of training. Always consider the requirements of your athletes when executing
these methods.
Metabolic Adaptations
Not only are isometrics beneficial for changes to the structure of the musculo-tendon unit, as
described above, but they can also be implemented to improve the metabolic functioning of
the tissue itself. As performance coaches, we all understand the value of the energy systems in
41
regards to the systemic organism. Without each of the energy systems functioning at a high
level, the ability of an athlete to adapt to almost any training stimulus will be blunted. Two of
the primary responsibilities of the energy systems include the ability to provide oxygenated
blood to the working muscles, and also the “clearance” of metabolic waste products. Both of
these rely on a high functioning oxidative energy system. Without these an athlete will not be
capable of recovering at an optimal rate (9-10).
However, based on the understanding of the physiological response to an isometric
contraction, the rapid exchange of blood to supply oxygen and clear accumulated metabolites
can become limited as the intensity of the contraction increases. For this reason, tissue that is
experiencing intense isometric contraction will accumulate greater metabolite build up than
that of a dynamic contraction. As the duration of the isometric increases, the accumulation of
metabolites is only further exaggerated. For this reason, the tissue can be trained to become
more efficient with the clearance of metabolites or to become increasingly “tolerant” due to
the implementation of specific isometric training protocols.
During most competitions, many actions are completed in a repeated manner. This can be seen
in swimming with the stroke required in each race, running in the sport of football, or a skating
stride in hockey. Although each of these actions completed are ultimately dependent upon the
environment surrounding them, in alignment with the dynamic systems theory, these
movements are, in general, going to be repeated in a similar fashion throughout the course of
competition. As the requirement of these muscles to repeatedly contract increases, their ability
to resist fatigue due to metabolic waste “build-up” becomes even more critical in performance.
If an athlete is able to “clear” and “tolerate” these by-products of high-intensity movements to
a greater extent, this athlete will be capable of maintaining both proper body positioning, as
well as retain their power output to a greater extent throughout the entirety of their
competitive event.
42
We, as coaches, teach a “sink and drain” concept. This is shown in figure 4.1 below. During
every high-intensity bout, an athlete’s “sink” is filled to an extent. This extent will vary based on
both the duration and intensity of the high-intensity bout. As the sink is filled, the “drain” is
responsible for the clearance of these high-intensity metabolites. Once an athlete’s “sink” has
been completely filled, whether the “sink” is too small, or the drain is not large enough, the
athlete’s ability to produce high-intensity efforts will be drastically reduced. Isometric training
can be completed to specifically improve both the “sink” as well as the “drain” of an athlete. To
read a more in-depth article on this aspect, click here.
Figure 4.1: The “sink” and drain analogy. As high-intensity efforts are completed, the aerobic system
(drain) and the “sink” (ability to tolerate metabolite accumulation) must both be trained to a high
extent, particularly for repeat-sprint sports.
Both of these adaptations can be realized by an athlete through the use of isometric training
when applied appropriately. The ability to “clear” these metabolic waste by-products relies
ultimately on blood flow to the muscle, while the muscle tissue itself must be trained to endure
these repeated contractions required in athletics without experiencing fatigue or potential
injury. Through the use of long duration isometrics at low intensities, the ability of the muscle
tissue to improve its strength at different, desired lengths, while continuing to allow
oxygenated blood flow to the muscle. These long-duration, yielding exercises can include
lengthened and shortened muscle states, based on the requirements of your athletes and/or
their sport.
43
These types of isometric contractions, yielding, long duration, are essential for postural
maintenance. If an athlete is not able to maintain their posture throughout play, their likelihood
of success will be drastically reduced. When the muscle strain is kept at a low enough level,
blood flow will not be restricted although the muscle is in a contracted state. This allows the
muscle to sustain a contraction for an extended period of time while keeping it in an aerobic
state. These are both vital factors when training for the “clearance” of metabolic waste while
also providing the muscle tissue itself with new levels of strength in the trained position.
However, the exact percentage of maximal voluntary contraction the muscle needs to stay
under to avoid occulsion depends on the muscle itself. For example, it has been shown that
30% of maximal voluntary contraction in the soleus and gastrocnemius was large enough to
induce muscular occlusion (11).
This newly improved strength, specifically at end ranges of motion can potentially aid in the
reduction of musculo-tendon injuries, as the muscle now has greater strength levels in the
length ranges in which injury is likely to occur. Basically, if the muscle realizes an increased
isometric force production, the ability to decelerate, the athlete will be capable of maintaining
a safe position. This returns to the jump example in section 1 and also the basketball athlete
going up for a lay-up discussed earlier. These adaptations can be achieved through these longer
duration isometrics, particularly at the end ranges of motions, where injury is more likely to
occur.
As covered in an earlier section, adaptations are dependent upon both the intensity (strain), as
well as the duration. With the long duration isometrics, a low intensity must be maintained in
order to sustain the duration of the contraction. However, the use of moderate duration,
moderate intensities can also lead to specific metabolic adaptations within the tissue.
Through the use of moderate duration and intensity training methods, the ability of the muscle
itself to “tolerate” metabolic waste can also be enhanced. By increasing the load and
positioning of the joints, a coach is able to create a form of occlusion within the muscle. This
44
reduced blood flow during isometric contractions is discussed in section 3. With the
understanding that oxygen is required in order to remain in an “aerobic” state, by reducing the
blood flow to a muscle immediately reduces the ability of this energy system. Not only is the
muscle driven into an anaerobic state (which has its own slew of beneficial adaptations when
utilized appropriately), the increased training load utilized will further enhance the strength of
the muscle tissue in the various tissue lengths utilized in training. This allows for a non-maximal
effort, while still requiring a high-level of recruitment and adaptation at the prescribed muscle
length.
By creating occlusion with the load and position, these metabolites are accumulated more
rapidly within the muscle and the muscle tissue learns to “tolerate” greater amounts of waste,
which are likely to occur in high-intensity situations. This ability to “tolerate” becomes
increasingly important at the end of a long shift in hockey, or at the finish of a 400 meter race.
Again, these yielding isometric contractions can be completed in either a lengthened or
shortened muscle position, as long as a strain and position utilized enhance the accumulation of
metabolic waste.
Each of these methods, the long duration, low intensity and moderate duration, moderate
intensity, serve a specific purpose in preventing both fatigue and potential tissue damage
experienced in the world of athletics. By improving both posture and tissue strength in specific
ranges of motion, power production is much more likely to be retained throughout competition
while also potentially reducing the likelihood of injury. When utilized appropriately, many of
the structural adaptations described above can be realized in conjunction with these potential
metabolic adaptations. Again, each of these methods, along with their implementation in
training, will be covered in an upcoming section of this book.
45
Nervous System Adaptations
Training through the utilization of isometrics also has the ability to change nervous system
function and efficiency based on the methods implemented. These adaptations range from
power output, to brain “plasticity”, and even skill learning in specific positions and velocities.
PAP (Post-Activation Potentiation)
This topic was covered extensively in our previous book “Applied Principles of Optimal
Development”. If you happened to miss it there, some of the basic information is provided here
on the effects of isometric PAP implementation. PAP or post-activation potentiation, is both a
local and systemic response to high-intensity, and low volume training. Isometric movements
are easily programmed to meet these requirements and when implemented correctly, lead to
an increased neural drive. As stated in our previous book, these isometric training protocols can
also be applied to increase force producing capabilities in a specific desired range of motion.
Brain “Plasticity”
Although this concept was recently demonstrated in literature and is relatively new in the sport
performance world, it has the potential to be extremely beneficial in the training process.
Through the utilization of isometric training principles, coaches are able to create “plasticity”
within the brain. This increased “plasticity” ultimately improves the capacity of an athlete to
learn, utilize, and recall the skill trained within this window of opportunity. This is due to the
increased utilization of the motor cortex during extended isometric training within the same
muscle group. Put simply, the motor cortex area of the brain specific to the utilized muscle fires
at a greater amplitude post-glute isometric training (12), or an athlete has an increased ability to
learn to utilize the trained muscle group in movement after this training method is
implemented.
46
Time under tension and athlete tolerance become the two primary factors in this training
adaptation. Based on research, the goal time under tension to optimally “prime” the motor
cortex for the glutes seems to be around twenty minutes. A coach can also increase the
requirement of the motor cortex during an isometric by adding a focal point for the athlete;
simply have them focus on one single point as they complete the isometric exercise (12). An
electric muscle stimulation machine can also be utilized on the trained muscle to increase
intensity even further. However, a coach should use extreme caution with this method as
extreme levels of soreness are seen after its implementation.
This adaptation serves as the basis for the “Glute Layering Model” which is a method designed
to increase hip function for every athlete.
Pain Reduction via Cortical Inhibition
It is hard to argue that pain and performance do not go hand in hand. When someone is feeling
pain, they are most likely not able to perform up to their full potential. Pain is inevitable at
times, but with isometrics it appears to be somewhat controllable. There are a slew of reasons
why pain may reduce performance (inhibition, safeguarding, fear etc.) and for the most part,
determining the exact reason it influences performance is near impossible to distinguish (it is
usually multifactorial). One interesting aspect in regards to isometrics is that they have been
shown to be a very useful tool in regards to dealing with and reducing pain.
The different influence influences of isometric exercises on pain control should not be
overlooked. It was found that unlike the isotonic exercises, isometric exercises caused greater
cortical inhibition within the brain. This cortical inhibition was associated with a reduction in
pain for 45 minutes (13,14). As a coach, such findings should jump off the page. 45 minutes often
sounds like the length of most training sessions in the weight room. Thus, isometrics might be a
useful tool to help not only build up tendon qualities (mentioned above), but also inhibit some
of the pain in the structures you are trying to build up. Theoretically, if isometrics are properly
47
applied in a warm up setting, either on the field or in the weight room, then pain may be
reduced and therefore the inhibition caused by the pain may no longer hinder performance.
Thus, isometrics allow one to dull the pain for an acute period, such as a training session or a
game. Because pain is possibly being inhibited and not reduced might mean the cause of the
pain still exists. Thus, such inhibition practices may be best used only when necessary.
RFD (Rate of Force Development)
Through the use of specific, high-intensity isometric training protocols, the ability to rapidly
produce power in a coordinated fashion can also be improved. However, it is important to
understand isometric training, when programmed with this goal in mind, is merely a foundation
to build upon. As athletics are completed in a dynamic nature, this coordinated force
production will only be maximized when trained in such a manner.
Isometric strength improvement may likely play a large role in both “pre-activation” and
overcoming of the inertia produced in dynamic movements. Pre-activation is ultimately the
ability to “pre-load”, or isometrically contract a muscle, or muscle group, prior to the execution
of a dynamic contraction. Pre-activation may have the ability to increase the initial muscle
stiffness and thereby improve the ability of the viscoelastic tendons to be stretched and recoil,
which may further improve RFD.
This ability to pre-activate a desired muscle to the appropriate tension level becomes
increasingly important in athletics due to the rapid force production required to achieve
success. Due to the short times available, maximal force is rarely, if ever, produced. When an
athlete is able to pre-activate, or isometrically load, a muscle, this athlete has initiated the
“ramp up” process of force production. This allows the execution of the dynamic portion, or the
“load and explode” of the SSC, in an efficient manner. By training with isometric programming,
the ability of an athlete to produce high-force, pre-activation may be increased. Ultimately
48
meaning they are capable of producing higher and more coordinated force production
throughout their SSC as the athlete completes high-speed/force movements.
The “toe loaded” cue provided in sprinting is a simple example of pre-activation. By preactivating these muscles, the athlete is able to translate absorption of force (upon ground
contact) into force production (what accelerates them in the desired direction) in a more rapid,
efficient manner. However, this is only possible when the isometric strength of the athlete’s
lower leg (in this example) is equal to, or greater than the ground reaction force. If this strength
is not present, the athlete’s lower shank will not be capable of overcoming these high forces
and will be required to complete an extended eccentric phase of movement. Thus, lowering
both their velocity and reactiveness off of the ground.
The ability to overcome the forces produced in dynamic actions can also be improved through
the implementation of isometric training. Movements in the arms and legs are relatively cyclical
in running and sport, although also vary, based on the competitive event as reaction to the
chain of events is also imperative to success. As an athlete produces rapid, high-velocity
movements, they must be capable of rapidly reversing the direction of those required limbs.
Without a high level of isometric strength, an athlete will be relatively slow in this ability and
will not be capable of producing the highest level of performance.
Pre-activation and the overcoming of inertia becomes further enhanced when an athlete has
been trained to attain the proper tendon stiffness relative to their muscle’s force production
capabilities. As movement progresses into more of a dynamic nature, coaches must not forget
the importance of placing the appropriate “shocks” on their athlete. When these factors are all
considered, athletes are able to utilize the SSC in the most powerful manner possible, while
continuing to make the movement seem effortless. Each of these adaptations will be covered
to a greater extent in the latter portions of this book.
49
It is important to note again that although these possible adaptations can be enhanced with the
use of isometric training, they will only be realized to the fullest in performance when also
trained in a dynamic manner. As every movement completed on the competition field is
dynamic in nature, this aspect cannot be overlooked. However, without the foundational and
specific range of motion strength developed in many of these isometric protocols the dynamic
training may not achieve the highest effect level, thus not allowing optimal performance.
Clearly, there are multiple possible adaptations coaches can target with the utilization of
isometric training principles. It is critical all understand the parameters that must be altered in
order to achieve the desired changes, such as time under tension, joint position, yielding vs.
overcoming, etc. Each of these can be implemented to the fullest extent when both the ideal
outcome, or physiological adaptation, along with the means of achieving that outcome are
understood to the highest level.
Other Potential Adaptations (As Highlighted by Supertraining)
Aside from the above mentioned structural adaptations, Russian researchers, such as Dr.
Bondarchuk, have investigated other specific adaptations that potentially occur with isometric
training protocols. As Supertraining
(15)
states “Static training produces the following changes:
the sarcoplasmic content of many muscle fibers increases, myofibrils collect into fascicles,
nuclei become rounder, motor end-plates expand transversely relative to the muscle fibers,
capillaries meander more markedly, and the layers of endomysium and perimysium thicken”.
Each of these adaptations are potentially induced due to “Static training” which refers to
training methods incorporating isometric muscular contractions. These adaptations require
further understanding and study, but can all be important for performance depending on the
competition. With the unitization of isometric training, myosin and myostrimus, the enzymatic
activity of myosin ATP-ase and aspartate-amino-transferase in skeletal muscle all significantly
increased in comparison to other forms of training using dynamic muscular actions. While we
50
have not necessarily seen any other papers highlight these exact changes, it could be due to
differences in what the researchers were looking at. Regardless, it should be noted that
isometric training induces specific adaptations that other forms of training may not.
51
SECTION 4 REFERENCES
1. Noorkoiv, Nosaka, and Blazevich. Neuromuscular Adaptations Associated with Knee Joint AngleSpecific Force Change. 2014
2. Abe T, Fukashiro S, Harada Y, Kawamoto K. Relationship Between Sprint Performance and
Muscle Fascicle Length in Female Sprinters. 1994.
3. Brechue W. Fascicle length of leg muscles is greater in sprinters than distance runners.
2014;(December). doi:10.1097/00005768-200006000-00014
4. Timmins RG, Bourne MN, Shield AJ, Williams MD, Lorenzen C, Opar DA. Short biceps femoris
fascicles and eccentric knee fl exor weakness increase the risk of hamstring injury in elite
football (soccer): a prospective cohort study. 2015:1-12. doi:10.1136/bjsports-2015-095362.
5. Kubo K, Kanehisa H, Ito M, Fukunaga T. Effects of isometric training on the elasticity of human
tendon structures in vivo. 2001:26-32.
6. Burgess KE, Connick M, Graham-smith P, Pearson SJ. On Tendon Properties and Muscle Output.
2015;(February). doi:10.1519/R-20235.1.
7. Clegg M, Harrison AJI. Muscle-tendon stiffness, running, stretch shortening cycle, jumping.
2005;(1990):101-104.
8. Lambertz D, Pe ÆC. Paired changes in electromechanical delay and musculo-tendinous stiffness
after endurance or plyometric training. 2008;(August 2017). doi:10.1007/s00421-008-0882-8.
9. Juel, C., Klarskov, C., Nielsen, J. J., Krustrup, P., Mohr, M., Bangsbo. J. Effect of high-intensity
intermittent training on lactate and H+ release from human skeletal muscle. AJP: Endocrinology
and Metabolism, 286, 245E-251. doi:10.1152/ajpendo.00303.2003.
10. Evertsen, F., Medbo, J., Bonen, A. Effect of training intensity on muscle lactate transporters and
lactate threshold of cross-country skiers. Acta Physiologica Scandinavica, 173(2), 195-205.
doi:10.1046/j.1365-201X.2001.00871.x
11. Ratkevi A, Mizuno M, Povilonis E, Quistorff B. Energy metabolism of the gastrocnemius and
soleus muscles during isometric voluntary and electrically induced contractions in man. 1998
12. Fisher, B. E., Southam, A. C., Kuo, Y., Lee, Y., Powers, C. M. Evidence of altered corticomotor
excitability following targeted activation of gluteus maximus training in healthy individuals.
NeuroReport. 2016; 27:415-421.
13. Rio E, Kidgell D, Moseley L, Pearce A, Gaida J, Cook J. Exercise to reduce tendon pain: A
comparison of isometric and isotonic muscle contractions and effects on pain, cortical inhibition
and muscle strength. J Sci Med Sport. 2013;16:e28. doi:10.1016/j.jsams.2013.10.067.
14. Rio E, Kidgell D, Purdam C, et al. Isometric exercise induces analgesia and reduces inhibition in
patellar tendinopathy. 2015;1277-1283. doi:10.1136/bjsports-2014-094386.
15. Siff and Verkhoshanksy, Supertraining. 2001
52
Section 5
The Implementation of
Isometric Training
“How To”
53
Isometric training protocols, as presented throughout this book, have been utilized in training
for ages. It is arguably one of the, if not the oldest forms of strength training. Simply look back
at books such as “Supertraining”, “Science and Practice of Strength Training”, or “Special
Strength Training Manual for Coaches”. Each of these books demonstrate the importance of
training through the use of isometric methods to some extent. However, due to its cloudy,
somewhat controversial past, on top of a lack of external, sport-specific appearance, isometric
training has been wrongfully cast aside by some. However, one should not be so quick to get rid
of an exercise regime that occurs in every aspect of human movement. Returning to the SSC, it
becomes clear that isometric strength is required to a high extent in every dynamic movement
completed. Whether we like it or not, isometrics play a prominent role in every cyclic and
acyclic action we perform, both in everyday life as well as in athletics. Like all regimes of work,
isometrics too have their role in developing the all-encompassing athlete.
In order to best understand how to implement any training regime or modality, the specific
adaptations, which are induced by using such training, must be continuously sought after and
then carefully analyzed. Only when these critical aspects of learning take place, are coaches
able to maximize the efficiency of the training programs implemented. Continuing to deepen
one’s knowledge and understanding of the body is necessary to continue to advance the
training protocols implemented for specific, desired performance outcomes.
Isometrics and the Brain
The utilization of isometrics to create strength in specific joint or muscular positions, or to
increase neural output are likely the most commonly understood adaptations by coaches.
However, there is an aspect that must be considered at an even higher level. That is the
connection between time under tension through isometric programming and the brain. The
brain is obviously a critical component of not only performance in an athletic competition, but
also of the upmost importance in everyday life. These connections to the brain through the use
of isometric training, which allows continuous time under tension, include an increase in motor
54
cortex firing (1) and the decrease of pain sensitivity. Both of these are described and discussed in
the previous section, but it is important coaches realize the implementation possibilities for
isometric training protocols expand much further than strength at specific ranges of motion.
Joint specificity
Like all types of muscular activity, isometric training is specific to the range of motion, or muscle
length, it is trained at. However, unlike movements that create a change in length, such as
eccentric and concentric contractions, isometric contractions do not. Due to this lack of length
change, the adaptations are more noted at the specific muscle lengths at which the training is
implemented when compared to other dynamic muscular contractions.
Due to the lack of muscle length change, the concept of joint specificity, or the improvement in
strength at the specific position, is well documented and understood. Ultimately, the position in
which the isometric exercise is completed in, is the location at which the strength gain will be
realized. Meaning the transfer of strength to other joint angles will be much less pronounced (2).
For example, if an athlete were to perform an isometric arm flexion at 90 degrees, the increases
in strength at 90 degrees will not necessarily transfer equally to strength at an arm flexion of
120 degrees. This concept should be well understood by coaches. Put simply, in regards to joint
specificity and isometric training, where training is completed, adaptations are realized.
However, as coaches delve deeper into the utilization of isometric training, joint specificity is
not always as straightforward as it initially appears. This becomes particularly apparent when
lengthened and shortened positions are compared. When an isometric is performed in a
lengthened position, transfer of strength to other joint ranges of motion is much greater than
those executed in a shortened position.
55
Due to these differences based on muscle length, it becomes possible to potentially label
isometric training and joint angle of isometric training in terms of general and specific to the
movement. If an athlete is attempting to induce a general adaptation to the target muscle,
lengthened position isometrics may be more appropriate than shortened position isometrics.
This is for two reasons:
1: Isometrics in a lengthened position will create general strength adaptations to a much
greater range of motion than shortened position isometrics. Therefore, the strength
adaptations are not as specific to the exact joint range of motion they are trained in (3).
2: Isometric training in a lengthened position causes different structural changes than isometric
training in a shortened position. As found by Noorkoiv and colleagues, strength gained while
training in a lengthened position as associated with an increase in hypertrophy, while training in
a shortened position was not related to such hypertrophic changes (3).
Clearly these are general adaptations that an athlete of any level can utilize to improve force
production throughout the entire range of motion. On the other hand, if an athlete is
attempting to induce specific adaptations to the target muscle, then the “critical” joint angle
and muscle length should be trained. This is not to say a lengthened position cannot also be a
specific position, as one might see with the hamstrings in sprinting. However, in some cases,
such as the takeoff after a drop jump, the critical joint angle where transition occurs from
eccentric to concentric action takes place (isometric phase) the muscle might be in a much
more shortened positioned. In such a case, this critical joint angle may play major importance in
the success of a specific movement and therefore, it may be desirable for the coach to train
specific isometric strength in this position.
56
The above concept of joint specificity can clearly be manipulated by using more than one joint
angle when training. By using multiple joint angles of different lengths, it may be possible to
induce the general structural adaptations as well more joint specific changes.
To highlight importance of training multiple joint angles, Folland and Colleagues investigated
the different effects of training isometrically at multiple joint angles compared to traditional
dynamic training (4). Compared to the isokinetic training completed, similar strength gains
between the dynamic group and the isometric training group were found. Therefore, isometric
training at multiple joint angles may possibly induce similar strength gains to dynamic training
throughout a full range of motion.
Critical Joint Angles
As mentioned above, unless the muscle is in a lengthened position, the joint angle at which the
isometric is being trained at will have specific strength adaptations to that one angle (joint
specificity). Therefore, when implementing isometrics in training to target specific joint angles,
muscle lengths and joint positions of the specific movement being trained should be carefully
analyzed. Through careful analysis, coaches can determine what the critical joint angles
isometric training should be completed at.
Critical joint angles, based on their sport specific nature, vary depending on the actions
required within a competitive action, and also the individual athlete. Thus, no one specific joint
angle can be deemed “most important” to incorporate into training. However, this does not
mean a critical joint angle cannot be determined for a specific athlete or movement.
This critical joint angle strength will play a vital role in the force production of the stretchshortening cycle (SSC). This is demonstrated in the jump examples in the opening section, the
importance of the isometric muscle action cannot be overstated. This ability to rapidly transfer
energy throughout the entire body in a systematic, and efficient manner becomes increasingly
57
important as athletes progress and develop. For this reason, section 7 has been dedicated to
the understanding, as well as implementation of training to optimize this critical aspect of
performance.
Once a critical joint angle is determined, isometric training of this specific joint angle can be
easily integrated into any training protocol. Critical joint angle isometric training can be
performed in several different ways (explosive, max effort, endurance, or oscillatory).
Depending on the specific desired outcome a method can be selected appropriately. This
decided isometric method can then be programmed in either isolation or in conjunction with
another movement. For example, if maximal voluntary overcoming isometrics are being
performed for multiple sets and reps, then a coach may want to ensure they are separated
from other exercises. However, if explosive isometrics are used for a short number of reps and
a small number of sets for a short period of time, then a coach may want to use these
isometrics in conjunctions with other dynamic movements that stress this critical joint angle. In
essence, this would be a method of post-activation potentiation.
The placement of critical joint angle isometrics within the training day depends heavily on the
type of isometric exercise selected. A multi-joint isometric exercise, such as a squat against the
safety racks, will be much more demanding compared to an isometric exercise of single joint at
a specific joint angle, such as an isometric knee flexion exercise in a lengthened position. Thus,
multi-joint, position specific isometric exercises might be best placed at the beginning of the
workout as opposed to a single joint isometric exercises, which might be best placed later on in
the training day.
Based on the previous sections, isometrics can be used in a multitude of ways and depending
on the exact method chosen, can be placed at nearly any point during a training program. Due
to the diversity of isometric training, it is imperative the exact method chosen is carefully
weighed, analyzed, and well understood before placed into the training program.
58
Figure 5.1: An overcoming isometric squat used to target a critical knee joint position that is often seen
in rapid, time dependent countermovement jumps.
Long muscle length
It is important to note that a critical joint angle is based entirely on the movement completed in
competition and can occur in fully extended joint angles. However, in most cases, this will not
be the case as critical joint angles typically do not occur at extreme muscle lengths. This is, in
part, due to the length-tension relationship in the muscle. A critical joint angle typically occurs
59
with some level of the muscle placed in a stretched position, but almost never in a fully
lengthened position (although there are a few exceptions). For this reason, fully extended joint
angle, with a lengthened muscle, are going to be considered separate from critical joint angles.
These reasons also extended to the specific adaptations that occur with long and short muscle
lengths. As mentioned above, the specific hypertrophic responses may differ and therefore, the
specific implementation of either method may be different .
Long muscle length isometrics have been shown to induce unique, specific adaptations to the
structure of the muscle. Long muscle length isometrics appear to induce greater hypertrophic
adaptations, while shorter muscle length adaptations appear to endurance specfiic, undefined
changes that are associated with an increase in strength (2). This could be due to the stretch that
is put on the sarcomeres when the muscle is isometrically contracting in such a position.
Caution and appropriate progressions should be used when implementing these long muscle
isometrics due to the increased stress placed upon them. If a muscle is overly taxed in a
lengthened position, it is possible that failure would lead to injury, due to the fact the muscles
can no longer stretch and the passive structures will have to aid in protecting the joint. For this
reason, performing lengthened isometrics might be best served in one of these two ways:
1) If a yielding isometric is used, it is best to start the athlete with a weight they are capable of
handling and the proper safety techniques are taught. It is not advisable to do this with highly
complex movements, such as an RDL. It is not only important to consider what target muscle is
being trained with isometrics, but it is also important to determine specific compensation
patterns that might occur if the athlete is “cheating” the exercise. For example, if performing a
long duration yielding isometrics in the bottom position of an RDL, the coach runs the risk of
putting too much stress on the spine. Instead, one might be best served to perform the yielding
isometrics in a more controlled setting, such as using a glute-ham, where a lighter load is used
and the back will be required to deal with smaller stabilization forces.
60
2) Using overcoming isometrics will allow for the coach and athlete to make immediate
adjustments and “fail safe”. With overcoming isometrics, there is no actually added external
load to the body. Instead, the load the athlete will handle is dependent on how much force
they produce. For this reason, if the athlete feels the need to reduce the force of the movement
in order to put themselves in a better position, then they can immediately do so. At the same
time, there is no need to ever spot the athlete when an overcoming is being performed, which
in turn will allow the coach to get into a better positions to watch form and cue appropriately.
For these reasons, overcoming isometrics can be performed more safely than yielding
isometrics when the exercise of choice is complex.
The time and place for long length muscle position isometrics is entirely up to the coach
implementing the training program. However, due to the difference in hypertrophic response,
one might assume that long length isometrics may cause more damage to the muscle (damage
to the muscle is one of the stimuli for hypertrophy) thus, these methods may be more
peripherally fatiguing and cause soreness. For this reason, we suggest that they are best put in
as either auxiliary work, if the exercise is being performed over a single joint, or as the primary
exercise, if the coach wants to cause general adaptations. It is hard to advise a specific blanket
statement regarding proper implementation of isometrics due to their extreme diversity. For
this reason, a coach should carefully analyze and weigh the pros and cons of each exercise prior
to implementation.
61
Picture 5.2: A complex isometric RDL used to target the hamstrings in lengthened position. This exact
exercise is not used for long duration isometrics due to the stress is puts on the lower back and if used,
should only be performed only by advanced athletes.
Exercises after isometrics
After an isometric is performed, we suggest that the target movement pattern is performed
afterwards for a minimum of a few (2-5) repetitions. With the goal of improving a specific
62
aspect, or movement involved in performance, the athlete must learn to utilize this force
production in the desired dynamic motor pattern.
The body and mind are deeply connected, and although the research has yet to provide full
clarity on this connection, it is our belief that if the motor pattern is performed dynamically
immediately following the isometric, the benefits of the isometric will be realized to a greater
extent. We feel this contrast, from isometric to dynamic movement, is one method available to
enhance transfer of training. This concept is derived from Yuri Verkhoshansky’s use of contrast
training and process of integrations of new motor patterns to develop a skill (5).
Weak ranges of motion
One of the unique qualities of isometric muscle contractions is that joint and limb remain static,
as opposed to concentric and eccentric muscle actions which involve changes in range of
motion and movement of the limb. When dealing with weak ranges of motion, a dynamic
muscle contraction, whether that be an eccentric or concentric contraction, are more difficult
to control than an isometric contraction.
For example, if someone is completing a form of rehabilitation after knee surgery, there are
clear contraindications for training at certain ranges of motion. Isometric protocols allow the
practitioner to target the specific, weak ranges of motion without causing concern in regards to
potential joint injury.
Aside from the obvious rehabilitation benefits, controlling joint range of motion to work on
strength in a controlled joint position has benefits in regards to the never ending debate of
mobility and stability. Isometrics can allow an individual to develop force in positions that the
body would not otherwise be able to dynamically produce a contraction in. Thus, isometric
training can be used as a precursor to dynamic training. Once the individual has developed
enough isometric strength in this weak position, the athlete can progress to producing dynamic
63
strength in this position and therefore, better develop stability and control. Together, specific
exercises in conjunction with isometric exercises can be used to increase mobility and stability.
Safe Joint Ranges
By nature, isometrics are very easy to control. The athlete is not performing any dynamic
movements and the body remains still (externally) during the exercise. Because of this, ranges
of motion can easily be controlled, as described in the rehabilitation example above. This is
common place in physical therapy, but often overlooked in the weight room. Pain does not
necessarily mean the entire system needs to be shut off, but instead the system might benefit
from training within its currently available limits.
64
Figure 5.3: Long muscle length, overcoming isometric hamstring used to increase strength at a weak
joint angles (can be due to previous injury). This can also be used to increase strength at a joint angle
which is considered dangerous. If individual does not have proper mobility, the above isometrics can
help improve strength in a safe, stable position.
Re-Educating the Maximal Voluntary Contraction
From a performance standpoint, coaches are always looking for ways to maintain intensity and
neural drive without causing negative effects on the body. When someone is experiencing pain,
is fresh coming off an injury, or even just a beginner in terms of lifting, performing a maximal
65
effort can be a fearful, and potentially dangerous situation. This athlete may associate such
maximal efforts with high risk and set themselves up for failure even before they attempt the
prescribed movement. Thus, their psychological appraisal of the lift and their own abilities puts
them at increased risk, when otherwise they may not be.
Placing this athlete into a high intensity situation, such as “maxing out” may not be in the best
interest of this athlete or the coach. Instead, a more controlled, less dynamic setting may be a
useful way of “re-educating” maximal intent. Maximal effort movements have the potential to
cause large neural outputs (increased motor recruitment) and again, neural is determined by
the brain. If the brain inhibits itself, then full potential cannot be reached. Thus, maximal
isometrics can be utilized in this instance as it ensures not only a high level of force output, but
also the ability of a coach to place the athlete in an appropriate, non-compromising, position
which will reduce the likelihood of injury. Hex Bar Deadlift Pin Pulls are a simple example of
this. With no dynamic movement, a coach can easily control body position and teach
appropriate technique for an athlete as they progress towards dynamic movement.
66
Figure 5.4: The Hex Bar Pin Pull can be applied for re-education of maximal force production purposes. It
can be easily viewed and cued by coaches to ensure athletes remain safe while producing high levels of
force.
Coaches can still take athletes from point A to point B, but the training wheels (controlled
isometric) allow the same result as a bicycle, without the risk of injury. Re-learning what
maximal tension is in a controlled environment, such as isometrics, might be a great teaching
tool for those who need to re-educate or are learning for the first time.
Importance of Tendon Stiffness
The isometric training regime has been well documented as a potent stimulator for tendon
adaptation. However, so have other means of training. One of the most common, and
67
considered by many practitioners to be the most demanding, training methods on tendon
strain (a possible stimulator of tendon adaptation) is the drop jump. A study by Burgess and
Colleagues evaluated the effectiveness of each modality in regards to improvements in tendon
stiffness (6). In the study, isometric, single leg calf raises, increased tendon stiffness by 61.6%
compared to only a 29% increase in stiffness from single leg drop jumps. Combining these
findings with those of Kubo and colleagues (7,8), and the evidence clearly highlight the potency
of isometric at improving tendon stiffness.
A stiffer tendon may allow for force to be quickly transmitted from the muscle to the
connecting structures to produce joint motion by reducing the need to take up the slack, which
would otherwise be present with a compliant tendon (9). Therefore, a stiffer tendon may allow
for quicker, more efficient transmission of force compared to a more compliant tendon and
therefore, possibly greater rate of force development. These improvements are critical for
rapid, and efficient transfer of force through the SSC, which will be covered in section 7 of this
book.
It is critical to note that in this section, there is a difference between rate of force development
in the muscle and rate of force transmission through the tendon. Rate of force development in
the muscle is used to describe the rate at which the muscle and its contractile properties begin
to develop force. The rate of force transmission is used to describe the rate at which the force,
which is developed in the muscle, is transmitted through the tendon to create movement. The
rate of force development cannot be expressed through movement until then tendon is
adequately taught, which in turn will allow for transmission of force to occur. Rate of force
development in regards to movement is the combination of rate of force developed in the
contractile portion of the muscle and the rate at which it is transmitted through the tendon.
If tendon stiffness were associated with greater RFD, then one would expect tendon stiffness to
be correlated with vertical jump height. As expected, in the mentioned Burgess study above,
there was a moderate, yet significant correlation between straight-leg, no countermovement
68
vertical jump height and tendon stiffness of the lateral Gastrocnemius. Some experts may argue
that a simple correlation between jump height and tendon stiffness may not be a proper
measure to determine tendon stiffness. Jump height is not only predicated on the structural
qualities of the tendon, but also the contractile properties of the muscle and an analysis that
would include the contribution of the contractile properties would be more beneficial.
Therefore, evaluating the differences between countermovement jump height and squat jump
height may be a better way to isolate the contributions of the tendon. This is why the
difference in squat jump and countermovement may be better for this comparison.
Due to the differences between a squat jump (no downward momentum and/or limited SSC
utilization) and the countermovement vertical jump (downward momentum and SSC
utilization), the tendon stiffness utilized becomes more apparent. Therefore, as proposed by
Bas Van Hooren and Frans Bosch, a better indicator of abilities to reduce muscle slack, and
therefore produce a higher magnitude of early rate of force development, would be highlighted
by a minimal difference in squat jump height and countermovement jump height (10).
A smaller difference between the squat jump and countermovement jump would indicate that
amount of force developed and rate of tension developed through the tendon of the two
movements would be similar and result in near equal jump heights. However, if the
countermovement jump is much higher than that of the squat jump, it may indicate that an
eccentric preload is required to take up the slack of a compliant tendon that would otherwise
not be readily taken up during a squat jump. Thus, a complaint tendon and an increase in
muscle slack would mean a lower rate of force development, a longer time to reach maximal
force, and a larger difference between countermovement jump height and squat jump height.
To answer this question, the results of a study done by Kubo and colleagues highlight the roel
of tendon stifness in regards to reducing the difference between countermovement jump
height and the squat jump height (7).
69
Magnitude versus Rate
It is important to note an increase in stiffness did not increase the countermovement jump
height. This is possibly due to the fact an increase in tendon stiffness will not increase the
magnitude of force being expressed in large amplitude movements. Large amplitude
movements allow for a longer duration for the muscle to reach maximal force and thus, the
rate at which force is produced plays less of a role, especially early stage rate of force
development. As proposed by several experts, the downward velocity created by a
countermovement may act to pre-load the tendon of the jump, thus taking up the slack and
masking the negative effects of the compliant tendon (10,11). Therefore, when the
countermovement is removed, the slack of the tendon will no longer be taken up by the
eccentric preload created by the downward countermovement and thus, a more compliant,
less stiff tendon will reveal itself through a large deficit between the two jump heights.
Therefore, a stiff tendon may simply play a role in quicker transmission of force from the
muscle to the tendon, which is why it may not have much influence when force is able to reach
its maximal, such as large amplitude movements where ample time is provided for force
development, similar to that of a full depth countermovement jump.
It is important to note that early and late stage rate of for development are two independent
qualities. Rate of force transmission from the muscle through the tendon is most likely
predicated on early stage rate of force development, which appears to be comprised of both
neural firing rates (12) and as suggested by the above evidence, tendon stiffness. However, early
stage rate of force development will not directly influence the amount of force being produced
in movements with ample time for force to be developed. Therefore, one should not expect
tendon stiffness to increase performance of large amplitude movements with large loading
times.
However, early stage rate of force development does play a role in situations where time is
limited, such as the squat jump. This may explain why the countermovement jump height was
70
not increased during the study, but squat jump height was. A countermovement jump has been
shown to take a long enough time for maximal force to be developed, with the time of
movement lasting roughly 0.5-1 second. However, a squat jump may take only 0.3 seconds to
execute (13). Thus, the small time frame does not allow for maximal force to be reached and
therefore relies more on early stage rate of force development, hence the improvement in
squat jump height but not the countermovement jump height.
As argued by Frans Bosch, most typical sporting movements have to occur over a short period
of time, with small amplitude of movement. Therefore, early stage rate of force development
may play a more critical role in sporting movements as opposed to lab-based, controlled
jumping exercises. Proper training should not only increase the magnitude of the force that can
be developed and transmitted, but also the speed at which it can be developed and
transmitted. To increase the rate at which force is transmitted and early rate of force
development, a stiff tendon may be necessary. Thus, isometric training may vital for developing
these critical tendentious adaptations.
71
Isometric training examples
Figure 5.4: Max effort (long and short muscle length)
72
Figure 5.5: Duration (long and short muscle length)
73
Figure 5.6: Barbell Split Jump With a “stick”
74
SECTION 5 REFERENCES
1. Fisher, B. E., Southam, A. C., Kuo, Y., Lee, Y., Powers, C. M. Evidence of altered corticomotor
excitability following targeted activation of gluteus maximus training in healthy individuals.
NeuroReport. 2016; 27:415-421.
2. Zatsiorsky, Vladimir M, and William J. Kraemer. Science and Practice of Strength Training.
Champaign, IL: Human Kinetics, 2006. Print.
3. Noorkoiv, Nosaka, and Blazevich. Neuromuscular Adaptations Associated with Knee Joint AngleSpecific Force Change. 2014.
4. Folland JP. Strength training : Isometric training at a range of joint angles versus dynamic
training. 2005;(September). doi:10.1080/02640410400021783.
5. Verkhosansky. N, and Verkhoshansky. Y. Special Strength Training Manual For Coaches. Rome,
Italy. 2011.
6. Burgess KE, Connick M, Graham-smith P, Pearson SJ. Pylometric vs Isometric Training Influences
on Tendon Properoties and Muscle Output. 2015;(February). doi:10.1519/R-20235.
7. Kubo K, Kanehisa H, Fukunaga T. Effects of different duration isometric contractions on tendon
elasticity in human quadriceps muscles. 2001:649-655.
8. Kubo K, Kanehisa H, Ito M, Fukunaga T. Effects of isometric training on the elasticity of human
tendon structures in vivo. 2001:26-32.
9. Clegg M, Harrison AJI. Elextromechanical Delay and Reactive Strength Indiciesof Sprint and
Endurance Trained Athlete. 2005;(1990):101-104.
10. Van Hooren B, Bosch F. Influence of Muscle Slack on High-Intensity Sport Performance: A
Review. Strength Cond J. 2016;38(5):75-87. doi:10.1519/SSC.0000000000000251.
11. Vas Hooren, Bosch, and Meijer. Can Resistance Training Enhance The Rapid Force Development
In Unloaded Dynamic Isoinertial Multi-Joint Movements? A Systematic Review. Strength Cond J.
2007.
12. Maffiuletti N, Folland JP, Tillin NA. Rate of force development : physiological and methodological
considerations. Eur J Appl Physiol. 2016;(March). doi:10.1007/s00421-016-3346-6.
13. Van Hooren and Zolotarjova. The Difference Between Countermovement and Squat Jump
perfoamnces: A Review of Underlying Mechanisims With Practical Application. Strength Cond J.
2017.
75
Section 6
Applied Isometric
Programming
76
Autoregulatory Progressive Resistance Exercise: Isometrics
Autoregulatory progressive resistance exercise (APRE) training methods have been around for
many years. Whether you learned the concept from the text of Supertraining, or from Dr. Bryan
Mann, autoregulatory training has been shown consistently as an effective means of training.
This section is not attempting to cover the history of APRE, but is instead written to explain how
APRE can be implemented in regards to isometric exercises. However, it should be clearly
stated that these concepts and ideas stem from Supertraining and should not be considered to
be completely our own ideas.
Why APRE
ARPE is a method designed to aid in the control of training loads for each athlete in terms of
both volume and intensity. Repetitions and loads are determined based on the athlete’s results
from the previous day/training session(s) and then regulated, if need be, based upon their
current performance. In other words, APRE attempts to remove the majority of the guesswork
involved with determining the amount of stress an athlete is capable of handling on a given
day.
Isometrics
Isometrics have been shown repeatedly as a potent method for strength development. Through
this book, this should be demonstrated clearly. However, it typically falls by the wayside during
training for several reasons:
1. Isometric and strength carry over is very specific to how the isometric is performed. For
example, depending on the joint angle being worked, gains across the entire range of
motion may not occur equally. Isometrics are often quoted as being joint specific and
gains are only seen + 15 degrees. Yes, this is somewhat true, but it has also been shown
77
that working a muscle while lengthened increases strength much more uniformly over
the entire range of motion compared to when the muscle is flexed. This means, when
performing isometrics, the joint angle has to either be very specific to the context of the
movement pattern being trained, or the muscle being targeted should be lengthened.
2. Isometrics are hard to monitor. If isometrics are performed by pressing a bar into pins or
safety catches, it is near impossible to gauge the amount of tension the athlete is
developing without some sort of force plate. Because this is the case, in order to best
monitor isometrics, it might be advisable to use a given weight and time frame for which
the isometric has to be held. For example, instead of pressing into pins, the athlete will
hold a specific amount of weight for a specific amount of time at a specific joint angle.
3. Isometrics are relatively difficult to progress. There is not much literature out there on
the usage of isometrics on elite athletes, especially in Western text. Because of this,
loading parameters are typically based off of single joint exercises, which based on the
musculature being used and total effort being exerted, are much different than multijoint isometrics. In order to solve this problem of inadequate loading parameters
regarding isometrics, it might be wise for a coach to utilize APRE for isometric training.
This exact process will be detailed out below.
Key elements of isometric training:
1. Joint angle must be specific to movement pattern (this is typically the joint where
muscles have to transfer from eccentric to concentric contractions, “transitioning angle”
or where maximal force needs to be produced), or targeted muscle must be in a
lengthened state.
2. Using a specific weight for a specific time will allow for adequate quantitative
monitoring.
78
3. APRE can be used to prescribe loads and remove guesswork.
Determining Your Loads
Before performing the APRE isometric protocol, the coach must first determine the athlete’s
level of isometric strength in the targeted position. For example, if the coach wants to use APRE
to train isometric squat strength at the transitional joint position of the vertical jump (near 90
degrees knee flexion), then the isometric strength testing must be performed using a squat
position near 90 degrees.
Once the position is determined, the coach will want to setup safety catches right below the
targeted squat position to allow for the athlete to lower the weight safely once the isometric
set is terminated.
In order to assess the athlete’s isometric strength, it may be advisable to use an isometric hold
of either 4 seconds, 6 seconds, or 8 seconds. Obviously a coach can choose whatever time they
would like, but the following instructions will refer back to a 4, 6, or 8 second maximal isometric
hold.
To properly establish the load for a given time period, the coach will progress with maximal
testing the same way as they would when testing dynamic squat strength. The coach will
progressively load weight on to the bar until the athlete has reached their maximal load for the
given time period. Once the load is determined, the following day the coach can begin using the
APRE isometric protocol.
79
Example:
Position: Transition point in the vertical jump
Max Strength: Isometric 6 second @ 365
Methods to develop Strength: APRE
APRE Isometric Training Table
Time
Adjustment
Time
Adjustment
Time
Adjustment
< 4 sec.
- 10 lbs
< 6 sec.
- 10 lbs
< 8 sec.
- 10 lbs
= 4-5 sec.
Stay
= 6-7 sec.
Stay
= 8-9 sec.
Stay
> 5 sec.
+ 10 lbs
> 7 sec.
+ 10 lbs
> 10 sec.
+ 10 lbs
Figure 7.1. APRE Isometric Suggested Loads Based On Set 3 Results
The APRE session will proceed as follows:
- Athlete will perform some level of general to specific warm-up sequence.
- Athlete will perform set 1 with 60% of maximal strength for given time period
- Athlete will perform set 2 with 80% of maximal strength for given time period
- Athlete will perform set 3 with 100% of maximal strength for given time period
- Athlete will perform set 4 with load determined by results from set 3 (see below)
The coach will assign a new load depending on the outcome of the set 3 (Figure 7.1). For
example, if an athlete were to hold their 6 second isometric max for more than 7 seconds, the
fourth set will be performed for as many seconds as possible with a load of +10 lbs more than
the load used for set 3. Maximal isometric strength for the given time frame (4, 6, or 8 seconds)
for the following session will then be adjusted to that of the load used for set 4.
80
Example APRE with a six second hold
Set 3- athlete holds 240 for 9 seconds
Set 4 – athlete holds 250 for 7 seconds
Six second isometric strength for the following workout is adjusted from 240 to 250.
81
Section 7
The Importance of Isometric
Strength in the SSC
Practical Application
82
Athlete Reactive Ability: The Stretch-Shortening Cycle
An athlete’s “reactive ability” is commonly mentioned when discussing change of direction, a
response to an external stimuli in competition, or generally an entire body change of some sort.
However, this section will deal with the “reactive” ability of an athlete to rapidly change the
length, activation, and velocity of the individual muscles utilized in training and game play. It is
these adaptations required within the muscle, nervous system, and other physiological factors
that are commonly left unmentioned that ultimately allow an athlete to complete the more
common, whole-body, “reactive” response. By the end of this section, each coach should not
only understand some of the physics, but also the concepts that can be implemented to
increase the reactivity of the individual trained muscle or movement.
The stretch-shortening cycle (SSC) forms the foundation of all dynamic movement and must be
understood prior to the implementation of specific isometric training protocols. As described
previously, the SSC consists of three muscle action phases, an eccentric (lengthening), an
isometric (no change in muscle length, also known as amortization), and finally the concentric
(muscle shortening) phases. Each of these phases serve a purpose in every step, every
movement, and every activity completed in both daily life and athletics.
The eccentric phase allows for shock absorption, while the concentric portion allows propulsion
to occur. The isometric phase, which occurs between the eccentric and concentric phases and
should be extremely well understood at this point, allows for the rapid transition from the
lengthening to the shortening actions. This phase, although brief, is vital for efficient energy
transfer. These phases should be well understood based on the countermovement jump
examples provided in the opening of this book.
Before diving more into some of the finer details, testing, and training, a basic, big picture of
the SSC must be better understood. A simple metaphor for the SSC is that of a coiled spring.
Just as a stretched, or lengthened, spring stores energy, the musculo-tendon unit functions in
83
this same manner. The elastic component is placed under stretch due to eccentric and
isometric loading of the muscle, leading to stored energy within the system. This stored energy
is released during the concentric phase of movement. This “stretch”, and thus power
production, can be increased through appropriate isometric training, as covered throughout the
previous sections of this book.
The exact mechanisms in which this SSC occurs are still being studied for increased
understanding, but the main concept remains. As an athlete increases their SSC, both power
production and efficiency are increased. With the majority of athletic events being determined
not only by the power an athlete is able to produce, but also their ability to produce highefforts repeatedly, the importance of a well understood and trained SSC cannot be overstated.
Components of the SSC
Within the SSC, there are multiple components that must all be considered in training. The
three major aspects within the SSC include the contractile components, the parallel elastic
component (PEC), the series elastic component (SEC), as well as the nervous system. The
contractile components include the actin and myosin, or the muscles themselves, while the PEC
and SEC include the elastic components such as the tendons. Each of these pieces have been
previously covered in regards to their adaptation due to isometric training.
84
Figure 7.1: Each of the components of the SSC
Each of these components play a vital role in the SSC and can each be improved specifically
within a training program. As every action completed is a learned skill, the body will continue to
adapt to whatever stimulus is provided during training. If an athlete is only focusing on
traditional strength work, the PEC, SEC, and some neural adaptations acquired through highvelocity SSC training may be lost. By focusing on each of these components within training
through the use of isometric means, as well as others, athletes will increase their ability to
generate rapid, efficient, reactive movements as their systems all function at the highest level,
together. Based on the previous sections of this book, it should be clear that isometric training
methods have the ability to affect each of these SSC components. However, other training
aspects must be continually implemented to achieve optimal results.
Power Production
Power production is increased in the musculo-tendon unit in the same manner as a stronger,
thicker spring provides greater energy return. As the muscle strength increases, the force
applied to the tendon, and thus the “stretch”, is increased. Simultaneously, as the “stretch” is
85
increased, the entire musculo-tendon unit is required to increase its force producing
capabilities, in an attempt to reduce the lengthening, or eccentric, phase. For this reason, both
strength and speed/plyometric training must be completed to ensure adaptations are
appropriate for muscle and tendon, respectively. If one becomes trained to a greater extent,
the likelihood of injury increases dramatically.
These same concepts can be seen in the spring example. As your fingers increase the stretch of
the spring, the energy stored is increased dramatically (tendon in the SSC). However, the force
required to maintain this stretch and effectively transfer this stored energy relies on the
strength of the fingers stretching the spring (muscle in the SSC). If the spring cannot withstand
the force applied during lengthening, it will snap and all energy is lost (weak, undertrained
tendon ruptures when muscles overpower). It is for this reason tendon stiffness and strength
are addressed through isometric training.
On the opposite side of the spectrum, if the force applied to the spring is too minimal (weak
muscle), the spring will not only never store energy (as there is no stretch applied due to lack of
force relative to its abilities), but the fingers that are applying force are going to take the brunt
of the effort and eventually fatigue. This is an example of an athlete that is extremely “springy”
or reactive, but is still relatively weak. Eventually the muscles will fatigue with every movement
and injury likelihood will be increased. Isometric training can also be implemented to increase
the ability of a muscle to produce force, this can be particularly effective at the critical joint
angle within the SSC.
Efficiency
Athletics not only revolves around the production of high power output, but also the ability to
repeatedly produce these efforts. For this reason, it is critical athletes utilize the most efficient
manner possible to create their high power outputs. With the idea that every step, hop, jump,
sprint, movement, etc. is a learned skill, efficiency can be improved in an extremely specific
86
manner. Between the three muscle actions completed, while also keeping the components
required by the SSC, coaches are able to build specific training protocols to increase this
systems efficiency.
Efficiency, or the ability of the SSC to provide “free energy” through elastic storage, is one of
the primary reasons the SSC is viewed as critical in sports performance. With the SSC requiring
a brief stretch (eccentric) prior to stopping (isometric) and reversing of the muscle contraction
(concentric). Each of these phases is a great starting point for specific training of the SSC.
Although this is a book aimed at the increased understanding of appropriate isometric training
implementation, for simplicity purposes, the order of the SSC will be kept intact. This means the
isometric phase will be discussed after the eccentric portion, as it was in the jump example in
the opening section of this book.
As described earlier, the eccentric muscle action occurs during muscle lengthening phase of
movement. It is this phase that is responsible for the deceleration of the muscle prior to it being
reversed into a concentric action. If the coils are to be stretched and utilized in the most
efficient manner, it must occur in a rapid fashion. If the force creating the lengthening action is
not able to be quickly overcome, energy will not be transferred efficiently in movement.
Not only is the deceleration of the muscle a critical task of the eccentric phase, it is important
coaches also understand this muscle action differs on a physiological basis as well. During this
lengthening phase, the motor pool is less activated, leading to fewer muscle fibers being
activated. This reduced recruitment of muscle fibers means less energy is required during the
eccentric portion of movement.
Returning to the “everything is a learned skill” concept, keep it simple. Train using eccentric
movements. As always, train with appropriate loads, commonly coaches can get carried away
with this aspect which can lead to potential injury to athletes. Encourage appropriate
movement prior to high training loads. This muscle action is not only important for the SSC, but
87
also in injury reduction. Teach your athletes to decelerate rapidly, effectively, and most
importantly, safely. Improving the eccentric, or force absorption, phase leads to an increased
storage of “free-energy” via the SSC within your athlete’s muscle fibers and tendons throughout
this phase. The muscle damage from eccentric movements will cause soreness in the muscles,
but once the soreness subsides, a strengthened and rebuilt muscle fiber remains. If this phase is
not specifically trained, then the ability to utilize the SSC to the highest extent will be
unavailable to athletes, as they are incapable of decelerating in a rapid fashion.
The isometric phase occurs extremely rapidly and it is commonly overlooked. However, it may
be the most critical phase in the transfer of force throughout the SSC. Without the isometric
phase, the moment in which the myosin-actin sites are firmly attached and deceleration is
stopped, the concentric phase is not possible. Regardless of how strong the eccentric force
abilities, or deceleration capabilities of an athlete are, if they are never able to overcome that
force, the tendons will never be placed into “stretch” and an athlete will not move in an
explosive manner. This is yet another example of the importance of the critical joint angle
training. However, other isometric training and the adaptations realized due to its
implementation should not be overlooked. It is for this reason the isometric phase is the most
critical to the optimization of the SSC, the sooner the myosin-actin sites are “locked” on, the
more the tendons are required to stretch during a movement, ultimately meaning increased
free-energy during the concentric portion of movement.
Pre-activation also plays a role in increasing both force production and efficient transfer of
energy through the SSC. By increasing the activation of a muscle prior to the lengthening phase,
more stretch is immediately placed upon the elastic components of the SSC. As an athlete is
preparing to contact the ground, whether it be in jumping, sprinting, etc. they can pre-activate
or “load their toe” in an increased effort to prevent energy from “leaking” during transfer of
energy through the SSC. This act is ultimately an isometric contraction, as there is no change in
muscle length. If the athlete is strong enough in this pre-activated state to transfer all of the
stretch to the tendons, then efficiency will be increased. However, if an athlete is not strong
88
enough to maintain this pre-loaded muscle length, an extended eccentric muscle action will be
required to decelerate the muscle prior to reversing the direction of force. This ability to rapidly
load will be covered in in greater depth in a later part of this section.
Again, just as with the eccentric phase of movement, train your athletes in an isometric fashion.
Train them using high-loads, to rapidly pull themselves into a position and rapidly “throw on the
brakes”, train them in their weakest positions, as isometric training is joint angle specific, train
them in the positions they will be required to transition between the eccentric and concentric
muscle actions. All of these methods are described in great detail in the earlier sections of this
book and are potential training methods coaches can implement based on athlete training age,
strength, and ability. The foundation for all of these abilities is force production or strength,
but that does not mean that this phase cannot be trained specifically to optimize its function.
Only when this phase of movement is maximized, can the stretching, or loading of the “springs”
be realized and utilized to the greatest extent.
Finally, the concentric phase of movement. This is the phase that typically gets all of the glory in
training and is well understood by coaches. However, it is critical that coaches realize if the SSC
is functioning optimally, this portion of movement is coupled with the free-energy provided
from the elastic components or coils that were stretched. This free-energy becomes even more
valuable in the movement efficiency of an athlete when it is understood that the myosin-actin
attachment sites are utilized to the highest extent during this portion. With the concentric
portion requiring the most energy to complete, the addition of a well-trained SSC will assist in
completing movements in this otherwise relatively “expensive” phase of movement in terms of
energy requirements.
In terms of training the concentric portion, ensure athletes are able to move through full range
of motion appropriately with strength, train them to rapidly drive out of their position with
power, train for speed and the ability to rapidly produce high levels of force. These training
methods will continue to develop a well-rounded athlete. One with both high force producing
89
capabilities, while also developing appropriate “spring stiffness” for maximal transfer of energy
through the SSC.
A simple example of these muscle action phases at work can be found in a hop through the
lower leg extensors. Starting with a falling athlete in mid-air (let’s say they have already
completed one hop) they are preparing to make contact with the ground again. This athlete will
pre-activate to some extent prior to ground contact in an attempt to increase the rigidity of the
SSC and transfer stretch to the elastic components. As contact is made, there is an eccentric
and isometric force applied to the muscle that ultimately lead to increased stretch being placed
on the tendons. The body then transfers to the concentric (shortening) phase of movement and
utilizes the free-energy stored to increase power production and efficiency of movement.
1. Pre-ground contact (mid-air)
3. Push-off (Concentric)
2. Absorbing ground contact of hopping
(Eccentric and Isometric)
Figure 7.2: The SSC phases as experienced during a hop. This occurs with every dynamic movement to
some extent. Each of the three phases can be seen in this simple example above in the three phases of
hopping
90
Advanced athletes are able to move through the eccentric and isometric phases more rapidly,
maximizing the free-energy produced from the stretched tendons. Ultimately optimizing their
SSC. The importance of the eccentric and isometric phases in training cannot be overstated, as
without the ability to absorb and transition high-levels of force, an athlete will execute
movements inefficiently and with a reduced power output. This ultimately leads to suboptimal
performance.
If this athlete did not have the eccentric ability to absorb the high-levels of force or the
isometric strength to transfer this force in the new direction, they would be functioning in a
reduced state. The athletes that lack these two phases of training are the ones who get “stuck
in mud” as their SSC is not optimally trained. Their bodies are not able to absorb and transfer
the high-force levels required. Thus, they must dissipate this energy in another manner
throughout their kinetic chain.
If one link within the kinetic chain is not able to absorb, transfer, or apply high-levels of force,
energy will “bleed” through this weak portion of the body. Ultimately, this leads to inefficient
movement and increased injury risk. The importance of these muscle action phases cannot be
overlooked in training. This concept will come into play when testing and evaluating the
function of an athlete’s SSC.
Recall the SSC is utilized in every dynamic movement to some extent. For maximal power
production and efficiency, athletes must not only have the “heavy duty springs” that allow
maximal transfer of energy, but also the ability to produce enough force to create stretch
throughout the increased springs. You wouldn’t put the same coil springs on your mountain
bike as your truck would you? The force output of the bike does not reach a level that those
springs would be required. Ultimately, the springs must match the athlete’s force producing
capabilities, if they are unable to produce enough force to generate a stretch, then muscle
strength must be focused on. If they are losing energy due to excessive stretch, then tendon
stiffness should be a primary goal. If the springs and force do not match up, or are not trained
91
appropriately, athletes will “leak” or “bleed” power with every movement. As covered above,
this not only reduces power production and movement efficiency, but also will increase
likelihood of injury.
Testing Protocols to Determine SSC Status
As movement velocity increases, while maintaining high forces, such as jumping and sprinting,
the importance of an appropriately trained SSC becomes even more apparent. Returning to the
foundation of the SSC, which is ultimately a movement that requires a rapid stretch (loading)
prior to a concentric muscle action phase, coaches can create specific testing protocols to
ensure athletes are training the appropriate aspect of this system. Coaches must ultimately
attempt to remove the SSC from a movement and compare that to a similar movement
executed while utilizing the SSC. A static, or pause jump (no SSC) compared to a
countermovement jump (SSC) is a simple method all coaches can implement as a testing
protocol. These two tests are described earlier in section 5.
With our understanding of the SSC, it should be well grasped that this jump will be of lesser
height than a “normal”, reactive jump. This is due to the power production abilities of the SSC
that have now been removed.
The countermovement jump height is utilized as a tool to monitor “efficient transfer of power”
within an athlete. As an athlete is now allowed to utilize the SSC, it is rare an athlete will have a
lower countermovement jump than the static jump. However, it does occur from time to time
in athletes that are not able to use their SSC effectively.
An efficient coach’s eye, will begin to notice the difference within the countermovement jumps
from one athlete to the next as well. Athletes that are able to “pull themselves” into their low
jumping position are utilizing their SSC to a greater extent and will be more efficient in their
movements. Almost always, these athletes capable of rapidly pulling down are the athletes that
92
both have the strength, as well as the tendon stiffness to optimize power production and
efficiency through this transfer
To maintain consistency within these jumps, require all athlete to keep their hands on their hips
and use a jump mat. When determining the results and future training programs applied, there
are never any exacts as all athletes vary to some extent. However, based on my personal
experiences as a coach, a 10% difference between the static and countermovement jump
seems to be about the optimal place for an athlete. This allows the change between each
athlete to remain relative to each of their own individual testing results. It would not make
sense to set a change at a specific numerical value, as athlete one may have a six inch higher
jump than athlete two. Thus, a percentage difference is utilized for individual athlete variances.
When determining results and the appropriate training program an athlete, or team, should
endure, these basic concepts can easily be applied.
If the static jump is relatively close to the countermovement jump, the athlete being tested is
relatively “strong” but has weak tendons. This can be seen as their ability to produce power
without the use of the SSC is high, while their power production does not increase to the
desired extent when the SSC is included in the movement. Ultimately, this athlete has the
relative force production capabilities of the truck, with the springs of a bike. They will bleed
power and move inefficiently through their SSC. This athlete, or team’s program should
emphasize more speed/plyometric training to increase their “coil stiffness”.
On the other hand, if their countermovement jump is extremely high in comparison to the
static jump the athlete will benefit from more “strength training”. I place this term in “quotes”
as this term can be quite broad and be achieved in many fashions. However, I strongly urge
coaches to always consider the quality of their training. Train with high intensities/loads,
maximal intent, and allow recovery time to maximize training results. This athlete is relatively
one we coaches typically term as “springy” (irony at its finest) but not relatively strong in
93
comparison to their body weight. An athlete of this nature will continue to benefit from
increasing their force producing capabilities as they are not currently strong enough to apply
large amounts of stress to their tendons. The athlete’s muscles will take the wear and tear and
abuse of each movement completed.
Some of the differences I have used in determining a team’s “training needs” based on the
results of these two jumps will be described below.
Practical Application of SSC Measurements
I have had the benefit of working with the sport of volleyball for the last two years. With
explosive jumping being the predominant movement that determines success (for hitters
anyways), vertical testing is completed regularly. It is from this consistent testing that I have
found that about a 10% difference between the static and countermovement jumps is optimal.
Again, this is entirely based on my experiences as a coach. However, it is this difference that I
look for when testing my athletes as my most explosive and efficient athletes seem to hover
right around this range. The changes throughout an off-season training can be seen in both the
static and countermovement jumps below in a collegiate volleyball team.
94
Figure 7.3: The long-term tracking and comparison of SSC to static jumps to apply appropriate training
means
This figure above can serve many purposes in both programming, as well as understanding the
response of the SSC due to specific training methods applied. Before each phase is broken
down it is important that I cover some basics of my programming and approach, and also how I
have laid out this graphic.
First off, I implement a block training method, meaning I implement certain aspects of training
with specific timing throughout my annual cycle. The main components that must be
understood to fully grasp the meaning of this figure are the intensity and the nature of the
repetitions completed (emphasized muscle action phase).
95
As far as the layout of the figure itself, testing results are demonstrated after each training
phase was completed. Testing was always completed during the middle of the week during a
download, which allows the athlete’s time to recover and supercompensate those adaptations
targeted in training. Keeping consistency with testing is critical, the timing of testing is no
different. By allotting a specific day during each download, the athlete’s recovery time (in days)
will remain consistent from test to test.
I have also color coded the cells for the percent difference between the two jumps. The orange
cell shows a team average that needs to be trained with a strength emphasis, as the difference
between the two jumps is large. The light blue represents a team average that requires more
plyometric training, or an athlete with “weaker coils” relative to their force producing
capabilities. Finally, the green cells represent a team average within what I have deemed an
“optimal range” (around 10%).
Upon returning to campus after winter break, testing is completed as a baseline for the
upcoming off-season. With the 12% difference between the two tested jumps, strength
improvements would benefit these athletes the most. This makes sense with athletes returning
from a break in training, along with that, their sport is jumping based (a learned skill just like
every other action completed that is not easily forgotten). These two factors lead to athletes
that are skilled jumpers, who lack strength, thus the difference between the two jumps makes
sense.
Throughout the eccentric, isometric, and reactive phases, the focus is placed on strength
enhancements (with percentages typically above 80%). For this reason, the difference between
the jump tests are decreased and the athletes actually transition into the blue cells.
Representing a need for increased plyometric based training. Although the primary adaptation
goal of these phases remain force production based, high-velocity, jump training is still
implemented. However, jump training in these phases are implemented with a “pause” in the
bottom position for both the eccentric and isometric blocks. Just as the static jump test requires
96
strength without the benefits of the SSC, jump training with a pause has the ability to increase
force production abilities as tendons are not utilized.
It is important to note that although the cell is green post-eccentric, this does mean an athlete
is in an optimal performance state. The green cell simply means that the athlete is in (what I as
a coach would consider to be) a state in which their tendons and muscles are each at an
appropriate strength when compared. Based on the previous year’s data, the fact that offseason training has just begun, and that strength serves as the foundation for increased power
production (jump height) strength improvements continued to remain the focus for the
isometric and reactive phases of training.
The power phase of training is implemented with lowered percentages (typically 55-80%) to
increase the velocity in which the movement is completed. At this time, due to the previous
training completed, athletes continue to be in a position in which they will see the most benefit
from increased speed and plyometric work, as their springs are now too weak when compared
to their muscle force abilities. After this phase of training, it becomes clear this goal of
increasing the elastic component of the SSC was accomplished as the difference between the
two is now up to 9% (near the desired 10% difference).
With volleyball being a fall sport, I am fortunate to keep the entire team throughout the course
of the summer to prepare at the highest level. Each of the muscle action phases are trained
again, although with slightly different progressions as the season is upcoming. Training is
completed for 5 weeks prior to a download, rather than just 3 weeks for all other training
phases. This increased accumulated stress leads to an overreaching state, followed by a high
parasympathetic drive during the download week (when testing is completed). This is likely the
reason a reduction in jump height is seen at this time as athletes are deep in a recovery state
(parasympathetic) and even by the middle of the week are still not supercompensated.
97
The hybrid training phase is the only phase in which I do not follow the block periodization
model. With pre-season rapidly approaching, programming is completed to ensure all physical
abilities required in practice/competition are available at their highest level. With the final
preparation phase of training prior to the beginning of the season, the primary emphasis of
training becomes plyometric and speed based, although strength training is still implemented
as well. This can be seen with the rapid increase in the countermovement jump and the
difference moving to 11%.
I am in no way stating that I am aware of every adaptation occurring within the athlete’s body
throughout this entire off-season. However, I do have a thorough understanding of my program
and the physiological adaptations that occur due to my collected testing data from multiple
years now. Understanding your athletes’ response to stress will come into play as coaches
attempt to manage stress throughout the season.
It is important to realize that these results represent an overall team average and although the
cell is orange, which represents a strength deficit, there are instances that commonly occur in
which an individual athlete will not match the “team average”. A perfect example of this can be
seen at the pre-season testing time. Although the average shows the team as being in a
proportionate spot, there are still athletes that show a higher difference than 10% between
their jumps. Ultimately meaning these athletes would still benefit from increased strength
based training. These individual variances must still be considered throughout tracking to
maximize each athlete’s SSC and performance.
By understanding where an athlete, or team is, in terms of their development, coaches are
much more able to achieve desired performance efficiently. These testing protocols, or others
that demonstrate a similar concept, allow a coach to determine the training adaptation that will
lead to the greatest performance benefits, and then create a program to execute these
adaptation goals. With the understanding that the SSC is required in every dynamic movement
to some extent, the training to maximize its potential is imperative to performance. It is also
98
critical to realize the multi-faceted approach that is required in order to train the SSC to the
highest extent, as it requires strength, speed, synchronization, and many others to a high
extent. Each athlete must have both the “heavy duty springs” as well as the force producing
abilities to cause those springs to stretch. These tests allow one to determine the needs of each
athlete’s “springs” or the force producing capabilities to deform those springs to create
efficient movement and high levels of power.
Overcoming Inertia
The importance of the isometric phase can be realized in dynamic movement in other means as
well. Specifically, through the overcoming of inertial forces produced within the limbs during
high-velocity executed actions. This ability becomes increasingly important in the execution of
cyclical movements of high force and velocity, such as the leg action during running and, when
implemented appropriately, has the opportunity to further enhance the SSC and RFD.
Any cyclical action, or one repeated continuously during competition, requires an athlete to
overcome inertia. This is due to the athlete producing high levels of force at high velocities and
then rapidly being required to reverse that action and begin producing force in the opposite
direction. This ability to rapidly reverse the direction of force production clearly relies heavily
on each of the three muscle action phases.
The lower limb action during sprinting is a simple example of this ability. As an athlete drives
through their foot in contact with the ground, they attempt to produce as much force as
possible in minimal time. The athlete then rapidly drives this leg up to re-position it to drive
back towards the ground to produce more force into the ground. It is important to realize the
only time an athlete is capable of increasing their running speed is when they are driving force
into the ground to propel them forward. The faster an athlete is able to get their leg into
position to repeatedly complete this action, the sooner they are able to propel themselves
forward with another foot strike.
99
The athlete capable of rapidly pulling their leg into the “cocked” position gives themselves a
clear advantage in a competition that requires sprinting. This is one reason exercises for the hip
flexors are completed in many training programs. It is this moment the ability of the athlete to
overcome the inertia produced in the rapid flexion of their hip becomes critical. If this strength
has not been acquired at the velocity the action is completed, it is likely the athlete will not be
capable of decelerating their leg in the appropriate “cocked” position. Ultimately leading to an
inability to rapidly re-accelerate their leg back towards the ground to move in the desired
direction.
This skill required in high level performance can be improved through the utilization of
isometric training, particularly at specific joint angles. The athlete that has the strength to
rapidly “throw on the brakes” at these desired positions can rapidly transition through these
cyclical movements, all while increasing their force output.
When applying these methods in an attempt to overcome inertia, the same isometric rules
apply as stated in the earliest sections of this book. Isometric training only improves strength at
the specific joint angles it is trained within (+10o from the position it is executed). This means
for the running example above, an athlete that lacks this ability would focus on maximizing the
strength of their hip extensors around 90o. It is the hip extensors that will be responsible for
decelerating the rapid, high force, hip flexion an athlete executes as they attempt to rapidly reposition their leg in the “cocked”, force producing position.
Coaches must also understand this 90o position (or around there), is only representative of the
joint angle, not necessarily the muscle length. As this occurs through the utilization of the SSC,
some of the length provided to create the joint angle will come from the elastic portions
(SEC/PEC) of the musculo-tendon unit after the rapid eccentric action that is required. That
being said, it is possible training in a slightly shorter, or more closed joint angle, during lower
100
velocity isometrics will more accurately provide the strength at the specific muscle fiber length
it is required at. This is due to the decreased “stretch” from these elastic qualities.
The understanding of the importance of the antagonist muscles and their biomechanical
requirements becomes increasingly important in this aspect of training. These muscles are
responsible for the rapid deceleration and reversal of force in the concentric action, the hip
extensors are an example of this above. Without the appropriate training in both the isometric
and eccentric muscle actions, these “brakes” will not allow for the rapid, smooth, and powerful
transition into the concentric action. In this case, the athlete would then not produce optimal
levels of force into the ground during hip extension as they would “bleed” power at the top
position.
The importance of the ability to overcome inertia and the agonist/antagonist relationship is
further increased when the “ABC” firing pattern of the muscle groups is better understood. The
“ABC” pattern can be viewed in three contraction phases. The three steps in this pattern
include a large burst by the agonist muscles early in the movement phase (A), followed by a
short braking burst from the antagonist muscles (B), and then a final push by the agonist
muscles to complete the movement (C). As the speed of a contraction increases, so does the
amount of braking force applied by the antagonists. The amount of force applied by the
antagonist (B phase) can be directly related to the net torque (or force) being produced as the
movement is executed. Put simply, the more the time and force the antagonist provides, the
less net force the movement produces in the desired direction. This can be seen in the
deceleration or “braking” from the hip extensors as the athlete attempts to rapidly reposition
their leg in sprinting.
Through proper training though, this “ABC” firing pattern is completed in a more efficient
manner throughout dynamic movements (1-3). These adaptations are realized due to greater
intramuscular and intermuscular coordination, as well as strength in specific joint angles.
Included in the intermuscular coordination is the contraction timing and force produced by the
101
agonist as well as the antagonist (4-10). As the athlete’s body becomes more capable of
producing force by the antagonist muscles in the specific joint angles required, the agonist has
the ability to produce greater force for a greater duration. This is due to the body’s
understanding that the antagonist is able to rapidly decelerate the joint, while maintaining its
safety.
To put this all back into our sprinting example. As the athlete attempts to rapidly re-position
their leg in the desired “cocked”, force producing position, the hip flexors are producing force
to pull that leg upwards (agonist in the “A phase”). At a specific position, the body becomes
aware that it will eventually become active to ensure the athlete is capable of safely executing
the desired movement. (B phase by an antagonist). Both the position at which the hip extensors
become active as well as the amount of force produced by them is determined by the training
completed and the strength of the antagonist hip extensors to rapidly produce force. Finally,
the hip flexors apply force to position the leg in the optimal position. As appropriate training is
completed for all of these aspects, the timing of the antagonist’s activation is likely to be
altered, along with the force it produces. This allows the hip flexors to produce greater force
throughout the range of the movement as the body understand that the “brakes” are
trustworthy and can be safely, rapidly applied.
An example of this can be seen in the two figures below, each representing a different athlete
(or perhaps an athlete at different level of training). The top figure shows an athlete of a lower
training level, while the second demonstrates a higher level trained athlete. The example of
sprinting is continued, with the left side being the moment in which the leg begins to develop
the force required to pull itself upwards. The activity of the hip flexors (agonist in this case) is
shown in the green, while the antagonist muscles (hip extensors) are represented in the red.
The darker the cell is colored, the higher force being applied by the respective muscle group
(flexors or extensors).
102
It is important to note that both the agonist and antagonist muscles are always active to some
extent during dynamic movement. However, in order to clearly demonstrate the “ABC”
contraction phases, the minimal firings that are likely to occur were left as the white area
(middle for the agonists and beginning/end for the antagonists). Based on this it becomes clear
it is possible for both the agonist and antagonist muscles to fire simultaneously, although this
would decrease the net torque produced throughout the dynamic contraction.
In the beginner athlete, in the “B” phase, this reduced torque becomes apparent due to the
extended period of time this phase requires. At the start, the hip flexors (green) are actively
pulling the leg upwards and continue to increase their force production in this “A” phase.
However, as this athlete’s antagonist muscles (hip extensors) have not been trained
appropriately, they become active earlier than ideal. This leads to a reduction in the force
producing capabilities of the hip flexors, which can be seen in the rapid change in shade of
green shown as the hip extensors become active. In this lower level athlete, the “B” phase is
not only active earlier in the movement, it also lasts for a greater period of time throughout the
movement. Ultimately leading to a reduced ability of the hip flexors to complete the “C” phase
with any force (lightly shaded green). This represents an athlete that is not able to rapidly
decelerate or “throw on the brakes” and one that will not produce the highest amounts of force
or velocity possible.
On the other hand, a higher level athlete (or the same athlete that has now been taught to
overcome inertia) will execute the “A” contraction phase with greater force (darker green)
while also being capable of producing this force for a greater relative duration of time
throughout the movement. I say “relative” as the actual amount of time to complete this
movement will, ideally, decrease in time as the athlete improves through training and skill
development. In this trained athlete, the “B” phase becomes shorter in duration and applies
force in a much more direct fashion. Although there may be more force applied in a single
instance from the antagonist muscles, the net force implemented will be less due to the now
rapid response from these muscles when compared with the “B” phase of the lower level
103
athlete described above. Finally, the “C” phase can produce higher amounts of force due to the
decline of co-contraction coming from the antagonist muscle groups.
This ability to decelerate and reverse the action of the limb, or overcome inertia, will lead to
increased net torque (force) production, while also reducing the amount of time required to
complete the movement. Returning to the sprinting example again, the higher level athlete will
be capable of producing greater amounts of force through their hip flexors throughout the
“cocking” action of running and then be able to still apply force from the hip extensors at the
appropriate timing and amount to maximize the cyclical action of running. Both of these are
goals every performance coach should be programming for to at least some extent in running
based sports. Clearly this skill can be applied to any sport requiring dynamic contraction.
Figure 7.4: A lower level athlete is demonstrated in this figure. This becomes apparent due to the
increased “braking time” required in the B phase of the contraction. This athlete will not produce the
highest levels of force possible as their hip extensors (antagonist in this example) are not capable of
efficiently decelerating the leg and overcoming the inertia developed
104
Figure 7.5: A higher level athlete is shown in this figure. This athlete has completed training to improve
their ability to rapidly “throw on their brakes”, which has led to a shorter, more efficient B phase. This
allows greater force to be produced by the agonist muscles (hip flexors in the sprinting example)
Again, it is important to note that co-contraction occurs in all dynamic movement, as this is
critical for joint stability (4-10). The ability of an athlete to reduce the level of co-activation during
certain phases of the muscle contraction (specifically the “B” phase of the antagonist muscles)
demonstrates adaptations within the nervous system and increase desired force output
(12,13,14,18,19).
This increased force will show improvements particularly during the early RFD
phase which appears vital for optimal athletic performance. The force producing abilities of the
antagonist muscles cannot be overstated, as the training of these muscle groups led to an
increase in power to a greater extent than the group training with just agonist exercises (11).
Even if a sport action is considered to be dominant in just one of those muscle groups, the
training of the antagonist groups can further enhance power production. Clearly training with
the potential adaptation of decreasing the co-contraction of antagonist muscles to increase net
torque becomes a relevant idea as a shorter, more succinct braking phase would mean that
agonist muscle action could contribute a larger portion of the total contraction time.
Not only is the strength, or force producing capabilities of the antagonist group critical for
continued improvement, the velocity at which they are trained must also be considered. This
can be seen in the fact that there is a sharp increase in co-activation (antagonist activation) as
the velocity of a movement increases. Just as the jump example in the opening section of this
105
manual, if the muscle cannot “ramp-up” at the required rate, the time required to complete the
action will be increased as the muscle is not able to achieve an isometric state in the SSC. This is
clearly not optimal for the performance in competition where time to produce force is
extremely limited.
As an athlete becomes more capable of producing maximal force in the desired joint angle (as
we understand that isometric force production adaptations are only available to a small range
outside of the angle in which they are trained), the transition to rapid eccentric/isometric
training can be incorporated to a high-level. These should continue to be completed in the
same joint angles that the “strength” version of the isometric was completed in.
Ultimately coaches must attempt to keep these concepts as simplified as possible. Firstly, the
athlete must be capable of producing force at the desired joint angle. Then the progression to
rapid eccentric/isometric training protocols can be completed appropriately. If one jumps
straight to the rapid eccentric/isometric programming, the ability to “ramp-up” will be limited
as the force producing capabilities are not available, let alone to produce them in a rapid
fashion. As this ability is still a form of the SSC, the appropriate training for this ability allows for
an even greater stretch at this point when the “brakes” are required at the highest levels. In
this example, the “cocking” position of running. This will in turn allow the agonist to produce
greater amounts of force in the allowed time, which leads to an even greater stretch of the SSC
when the brakes are hammered down.
The implementation of these isometric training principles in this logical progression can
continue to improve the SSC and RFD in an athlete by allowing a more rapid transition during
cyclical motions required in athletics. These two adaptations, to the SSC and RFD
improvements, are typically both primary goals to achieve performance improvements.
106
SECTION 7 REFERENCES
1. Remaud, A., Cornu, C., Guével, A. (2009). Agonist muscle activity and antagonist muscle coactivity levels during standardized isotonic and isokinetic knee extensions. Journal of
Electromyography and Kinesiology, 19(3), 449-458. doi:10.1016/j.jelekin.2007.11.001.
2. Baker, D., Newton, R. (2005). Acute effect on power output of alternating an agonist and
antagonist muscle exercise during complex training. Journal of Strength and Conditioning
Research, 19(1), 202-205. doi:10.1519/1533-4287(2005)19<202:AEOPOO>2.0.CO;2.
3. Karst, G., Hasan, Z. (1987). Antagonist muscle activity during human forearm movements under
varying kinematic and loading conditions. Experimental Brain Research, 67(2), 391-401.
doi:10.1007/BF00248559.
4. Cormie, P., McGuigan, M., Newton, R. (2011). Developing maximal neuromuscular power: part 1
– biological basis of maximal power production. Sports Medicine, 41(1), 17-38.
doi:10.2165/11537690-000000000-00000.
5. Aagaard, P., Simonsen, E., Andersen, J., Magnusson, S., Bojsen-Møller, F., Dyhre-Poulsen P.
(2000). Antagonist muscle coactivation during isokinetic knee extension. Scandinavian Journal of
Medicne & Science in Sports, 10(2), 58-67. doi:10.1034/j.1600-0838.2000.010002058.x.
6. Bazzucchi, I., Riccio, M., Felici, F. (2008). Tennis players show a lower coactivation of the elbow
antagonist muscles during isokinetic exercises. Journal of Electromyography and Kinesiology,
18(5), 752-759. doi:10.1016/j.jelekin.2007.03.004
7. Maeo, S., Yoshitake, Y., Takai, Y., Fukunaga, T., Kanehisa, H. (2013). Effect of short-term maximal
voluntary co-contration training on neuromuscular function. International Journal of Sports
Medicine, 35(2), 125-134. doi:10.1055/s-0033-1349137.
8. Sale, D. (1988). Neural adaptation to resistance training. Medicine and Science in Sports and
Exercise, 20(5Suppl), S135-145.
9. Rutheford, O., Jones, D. (1986). The role of learning and coordination in strength training.
European Journal of Applied Physiology, 55(1) 100-105.
10. Dal Maso, F., Longcamp, M., Amarantini, D. (2012). Training-related decrease in antagonist
muscles activation is associated with increased motor cortex activation: evidence of central
mechanisms for control of antagonist muscles. Experimental Brain Research, 220(3-4), 287-295.
doi:10.1007/s00221-012-3137-1.
11. Carolan, B., Cagarelli, E. (1992). Adaptations in coactivation after isometric resistance training.
Journal of Applied Physiology, 73(3), 911-917.
107