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National Academy of Sports Medicine
Integrated Reactive
(Plyometric)
Training
Integrated Reactive Training
Copyright © 2008 National Academy of Sports Medicine
Printed in the United States of America
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Distributed by:
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Author: Dr. Micheal Clark, DPT, MS, PES, CES
Integrated Reactive Training
Introduction
The demands imposed during training must reflect those incurred during advanced phases of rehabilitation,
reconditioning, and training. This is referred to as the specificity of training concept.1 Enhanced performance during functional activities emphasizes the ability of the muscles to exert maximal force output
in a minimal amount of time (rate of force production). Success in most functional activities depends on
the speed at which muscular force is generated. Power and reactive neuromuscular control represent a
component of function and are perhaps the best measure of success in activities that require rapid force
production. Reactive training utilizes the stretch-shortening cycle (integrated performance paradigm)
to enhance neuromuscular efficiency, rate of force production, and reduced neuromuscular inhibition.
Reactive training heightens the excitability of the central nervous system, which improves performance.
This course reviews the various components of reactive training so that the health and fitness professional
understands how to incorporate reactive training into an integrated training program.
Section I:
Section II:
Section III:
Section IV:
Section V:
Section VI:
Section VII:
Appendix
References
The Definition and Purpose of Reactive (Plyometric) Training
The Three Phases of Reactive Training
Physiological Principles of Reactive Training
Proposed Mechanisms by Which Reactive Training Enhances Performance
Scientific Rationale for Reactive Training
Reactive Training Program
Summary
The speed of muscular exertion is limited by neuromuscular coordination. This means that the body moves
only within a range of speed set by the central nervous system.4 Optimum performance depends on the
speed at which muscular forces can be generated. It is generally accepted that optimum performance
in sports and other functional activities requires both technical skill and power. Skill is the ability of the
neuromuscular system to coordinate the kinetic chain to allow for quick and accurate movements in all
directions. Power is the ability to exert maximal force in the shortest amount of time. Power is most
efficiently increased through a combination of an increase in the amount of force that the muscle can
produce and a decrease in the amount of time taken to produce that force. 5 As described in this manual’s
final section, reactive training utilizes a three-level training program to improve both neuromuscular
efficiency and the range of speed set by the central nervous system.
Integrated Reactive Training
Figure 1: Skill and Power
SKILL is the ability of the neuromuscular system to coordinate the kinetic chain to allow
for quick and accurate movements in all directions.
POWER is the ability to exert maximal force in the shortest amount of time.
Integrated Reactive Training
Section I:
The Definition and Purpose
of Reactive (Plyometric) Training
Reactive (plyometrics) training is defined as a quick, powerful movement involving an eccentric contraction
followed immediately by an explosive concentric contraction.2 This defines a stretch-shortening cycle or
an eccentric-concentric coupling phase. Reactive training exercises stimulate the body’s proprioceptive
mechanism and elastic properties to generate maximal force output in the minimal amount of time.2
Figure 2: Purpose of Reactive Training
m Enhance the excitability, sensitivity, and reactivity of the neuromuscular system
m Enhance the rate of force production
m Increase motor unit recruitment
m Increase motor unit firing frequency
m Increase motor unit synchronization
Reactive training enhances motor learning and has five distinct purposes: to enhance the excitability,
sensitivity, and reactivity of the neuromuscular system; to enhance the rate of force production; to
increase motor unit recruitment; to increase motor unit firing frequency; and to increase motor unit
synchronization.
Maximal sensorimotor integration allows for the development of complex motor programs. Reactive
training also enhances muscular function and optimizes the appropriate activation of prime movers and
synergists. In addition, reactive training causes reciprocal inhibition of antagonists, as demonstrated by the
ability to perform complex, explosive movements. Reactive training optimizes neuromuscular efficiency
by enhancing motor unit recruitment, increasing motor unit firing frequency, enhancing firing patterns
for specific functional patterns, and improving motor unit synchronization at lower force outputs. All
movement patterns that occur during functional activities involve a series of repetitive stretch-shortening
cycles modeled in the integrated performance paradigm.
Integrated Reactive Training
Figure 3: Integrated Performance Paradigm
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As illustrated in Figure 3, the integrated performance paradigm includes eccentric deceleration, isometric
stabilization, and concentric acceleration. The health and fitness professional must use specific functional exercises to adequately prepare the client to return to the rigors of his or her specific activity.6,7,8
Traditional training, reconditioning, and rehabilitation in which heavy loads are emphasized induce greater
hypertrophy and increases in strength, but may not effectively improve maximal power output, functional
strength, or neuromuscular efficiency.9 One of the most remarkable aspects of skeletal muscle is its
adaptive potential. If a muscle is systematically and functionally stressed, it will allow continual adaptation
and optimum performance. A baseball pitcher utilizes the integrated performance paradigm to produce
maximal explosive concentric contractions. To replicate these forces during training, reconditioning, and
rehabilitation is beyond the scope of traditional training. For example, the Cybex 6000 reaches maximal
angular velocities of 500 to 600 degrees per second, which is nonspecific to the greater than 7,000 to
10,000 degrees per second of shoulder angular velocity during baseball pitching.10 Consequently, specific
functional exercises should be an integral component in every training, reconditioning, and rehabilitation
program to facilitate a complete functional return and allow optimum performance.
The health and fitness professional should utilize reactive training to replicate the explosive muscular
contractions that occur during most functional movements.
Integrated Reactive Training
The neuromuscular system must react quickly following an eccentric contraction to produce a concentric
contraction and impart the necessary force (acceleration) in the appropriate direction. Muscles produce
the necessary change in the direction of the object’s center of mass.4 Specific functional exercises that
emphasize a rapid change in direction must be utilized to prepare each client for the functional demands
of his or her specific activity. Reactive training provides the ability to train specific movement patterns
in a biomechanically correct manner, thereby more functionally strengthening the muscle, tendon, and
ligaments. The ultimate goal of reactive training is to decrease the amount of time between an eccentric
contraction and a concentric contraction. 5
Integrated Reactive Training
Section II:
The Three Phases of
Reactive Training
There are three phases involved in reactive training: the eccentric phase, the amortization phase, and the
concentric phase.
Figure 4: Phases of Reactive Training
THREE PHASES OF REACTIVE TRAINING
m Eccentric Phase
m Amortization Phase
m Concentric Phase
The Eccentric Phase
This phase increases muscle spindle activity by prestretching the muscle prior to activation.11,12 Potential
energy is stored in the elastic components of the muscle during the force-reduction phase. Prolonged
loading prevents optimum exploitation of the myotatic stretch reflex.13,14
The Amortization Phase
This phase involves dynamic stabilization and is the amount of time that elapses between the eccentric
contraction (force reduction) and the initiation of the concentric contraction (force production).2 The
amortization phase is also referred to as the electromechanical delay between the eccentric and concentric contraction, during which the muscle must switch from overcoming force to imparting the force
in the intended direction.4 A prolonged amortization phase results in less than optimum neuromuscular
efficiency secondary to a loss of elastic potential energy. The more rapidly an individual switches from an
eccentric contraction to a concentric contraction, the more powerful the response.2
The Concentric Phase
This phase involves force production and results in enhanced muscular performance following the eccentric phase of muscle contraction.
Integrated Reactive Training
Section III:
Physiological Principles of
Reactive Training
Reactive training utilizes the elastic and proprioceptive properties of a muscle to generate maximum
force production (reference the integrated performance paradigm). 2 Reactive training stimulates the
body’s mechanoreceptors to facilitate an increase in muscle recruitment over a minimal amount of time.2
Mechanoreceptors are specialized sensory neurons located within the muscle that provide information
to the central nervous system as to the degree of muscular distortion. The central nervous system then
uses this sensory information to influence muscle tone, motor execution, and kinesthetic awareness.12
Stimulation of these receptors can cause facilitation, inhibition, and modulation of both agonist and antagonist muscle activity. This enhances neuromuscular efficiency and functional strength. Muscle spindles and
Golgi tendon organs (GTO) provide the proprioceptive basis for reactive training.9,15,16,17,18
The Elastic Properties of Muscle
Several authors19,20,21,22 have reported that an eccentric contraction immediately preceding a concentric
contraction significantly increases the force generated concentrically as a result of the storage of elastic
potential energy. During the loading of the muscle, the load is transferred to the elastic components
(parallel elastic elements and series elastic elements) and stored as elastic potential energy. The elastic
elements then contribute to the overall force production by converting the stored elastic potential energy
to kinetic energy, which is then utilized to enhance the contraction.19,21,23 The muscle’s ability to use the
stored elastic potential energy is affected by the variables of time, magnitude of stretch, and velocity of
stretch. Increased force generation during the concentric contraction is most effective when the preceding eccentric contraction is of short range and is performed without delay.17
Integrated Reactive Training
Figure 5: Elastic Properties of Muscle
The improved muscular performance that occurs with the prestretch in a muscle is the result of the
combined effects of both the storage of elastic potential energy and the proprioceptive properties of the
muscle.19,20,24 The percentage that each component contributes is unknown.20 The degree of enhanced
muscular performance is dependent upon the time elapsed between the eccentric and the concentric
contraction.24 Integrated training enhances overall kinetic chain neuromuscular efficiency. Training that
enhances neuromuscular efficiency decreases the time elapsed between the eccentric and concentric
contraction, thereby improving performance.
10
Integrated Reactive Training
Section IV:
Proposed Mechanisms by which
Reactive Training Enhances Performance
There are three proposed mechanisms by which reactive training improves performance: enhanced muscle
spindle activity, desensitization of the GTO, and enhanced intramuscular and intermuscular neuromuscular
efficiency.
Figure 6: Reactive Training and Performance Enhancement
PROPOSED MECHANISMS BY WHICH REACTIVE
TRAINING IMPROVES PERFORMANCE:
m Enhanced muscle spindle activity; desensitization of the GTO
m Enhanced intramuscular neuromuscular efficiency
m Inter-muscular neuromuscular efficiency
Enhanced Muscle Spindle Activity
The speed of a muscular contraction is limited by the neuromuscular system. The kinetic chain will move
only within a set speed range, regardless of how strong a muscle is.2 The faster a muscle is loaded eccentrically, the greater the concentric force production.12
Figure 7: Muscle Spindle
11
Integrated Reactive Training
Desensitization of the Golgi Tendon Organ
Desensitizing the GTO increases the stimulation threshold for muscular inhibition, ultimately allowing
increased force production with a greater load applied to the musculoskeletal system.2
Figure 8: GTO
Enhanced Neuromuscular Efficiency
Reactive training may promote changes within the neuromuscular system that enable the individual to
have better neuromuscular control of the contracting agonists and synergists, thus enabling the central
nervous system to operate more automatically.4 These neural adaptations lead to enhanced neuromuscular
efficiency even in the absence of morphological adaptations. Exploiting the stretch reflex, inhibiting the
GTO, and enhancing the ability of the nervous system to react with maximum speed to the lengthening
muscle optimizes the force produced by concentric contraction.
12
Integrated Reactive Training
Section V:
Scientific Rationale for
Reactive Training
Numerous studies have shown the benefits of implementing an integrated reactive training regimen,
ranging from decreases in injury to increases in strength and endurance. Chimera et al. showed that a
six-week plyometric training program improved hip abductor and adductor coactivation ratios to help
stabilize the knee during landing.25 A study by Wilkerson et al. of 19 female basketball players showed an
improved hamstring-to-quadriceps ratio, theorized to improve dynamic knee stability during the eccentric
deceleration phase of landing.26 Irmischer et al. showed that a knee ligament injury-prevention program
implementing progressive plyometric training reduced landing forces thought to help prevent knee injuries.27 In addition, Hewett et al. demonstrated decreased peak landing forces, enhanced muscle balance
ratio of the hamstrings and quadriceps, and a decrease in anterior cruciate ligament injuries in female
soccer, basketball, and volleyball players when a reactive neuromuscular (plyometric) training program
was implemented.28 Beyond injury prevention, plyometric training has been shown to increase strength
and power. In a study by Markovic et al., a 10-week plyometric training program increased leg power and
performance. It increased squat jump height 6.5% and countermovement jump height 6.3%. 29 Hoffman
et al. determined that a loaded squat-jump training program improved one repetition maximum in squats
and power clean strength. The eccentrically loaded squat jump was theorized to be the catalyst for the
strength improvements shown.30 Of special interest is the study by Spurrs et al., which demonstrated
that incorporating a plyometric training program increased countermovement jump height, decreased
3K run time, and increased running economy. 31 These improvements in performance were attributed to
increased musculotendinous stiffness as a result of implementing a reactive neuromuscular (plyometric)
training program.
13
Integrated Reactive Training
Section VI:
Reactive Training Program
An effective reactive training program has several fundamental requirements: adequate functional strength,
adequate kinetic chain structural and functional efficiency, and adequate stabilization strength.
Specificity
For optimum carryover, there should be a high degree of similarity between the training activity and the
functional activity. By performing reactive training during integrated movement patterns, the exercise has
specific physiological, biomechanical, metabolic, and neuromuscular carryover. 32,33,34
Adequate Functional Strength
A greater functional strength base and greater neuromuscular efficiency allow greater force production,
thus resulting in optimum performance. Optimum levels of functional strength and neuromuscular efficiency
allow optimum eccentric, isometric, and concentric contractions during integrated movement patterns
(muscle contraction spectrum). Optimum eccentric neuromuscular control allows for more efficient use
of stored elastic potential energy, and a greater concentric contraction.
Adequate Stabilization Strength
High levels of isometric stabilization strength and neuromuscular efficiency decrease the amortization
phase. This decreases the amount of time elapsed between the eccentric contraction and the concentric
contraction, resulting in decreased tissue overload and decreased potential for injury. A reactive training
program is an essential component for all integrated training programs. The key to an effective, integrated
reactive training program is the design and implementation of the program. Each program should be
progressive, systematic, multiplanar, and activity specific.
Reactive Training Criteria
Each individual must be thoroughly screened prior to beginning a training program. The individual must
have an unremarkable medical history. The individual must receive a thorough kinetic chain assessment
that includes a review of the following: posture, gait, muscle balance, core, neuromuscular control and
function.
14
Integrated Reactive Training
Reactive Training Assessment
To establish a baseline measurement, it is important to assess an individual’s power production and neuromuscular control prior to initiating an integrated training program. The health and fitness professional
can use the vertical jump test (Figure 9) and the shark skill test (Figure 10) to assess power and reactive
neuromuscular control, respectively.
Figure 9: Vertical Jump Test
15
Integrated Reactive Training
Figure 10: Shark Skill Test
Safety Requirements
Each individual should have supportive shoes, access to a resilient training surface, a proper program, and
knowledgeable supervision prior to beginning a reactive training program. 5,35
Training Variables
An integrated, reactive training program can be varied like other components of an integrated training
program. Training variables that can be manipulated include plane of motion, range of motion, external
load, amplitude of movement, contraction velocity, muscle action, duration, intensity, and frequency.
16
Integrated Reactive Training
Training Progression
The training program proceeds from simple to complex, stable to unstable, body weight to extra resistance,
and low load to high load, and includes proper utilization of the plyometric stress continuum.
Intensity
The intensity of the exercise is controlled by the selection of the exercise. For example, a two-leg squat
jump is less intense than a one-legged hop. Intensity is also controlled by the use of external load and
manipulating the duration, rest periods, and frequency of the exercise.
Overtraining
Overtraining is a pathological state that results from cumulative neuromuscular and metabolic fatigue.
Signs of overtraining include prolonged foot contact, lack of neuromuscular control, decreased vertical
height or horizontal displacement, and longer rest periods.11
NASM has designed a systematic, progressive, and integrated balance training program utilizing the
Optimum Performance Training (OPT) model. The program includes three phases: Level 1, Stabilization;
Level 2, Strength; and Level 3, Power.
Figure 11: OPT Model
17
Integrated Reactive Training
Reactive Stabilization
In reactive-stabilization training, exercises involve little joint motion. They are designed to establish optimum
landing mechanics, postural alignment, and reactive neuromuscular efficiency. When an individual lands
during these exercises, he or she should hold the landing position for 3–5 seconds before repeating.
Box Jump Up w/Stabilization – Front 1
Box Jump Up w/Stabilization – Front 2
Box Jump Up w/Stabilization – Side 2
18
Box Jump Up
w/Stabilization – Side 1
Box Jump Up w/Stabilization – Turning 1
Box Jump Up
w/Stabilization – Turning 2
Integrated Reactive Training
Box Jump Down w/Stabilization – Front 1
Box Jump Down w/Stabilization – Front 2
Box Jump Down w/Stabilization – Side 2
Box Jump Down
w/Stabilization – Side 1
Box Jump Down w/Stabilization – Turning 1
Box Jump Down
w/Stabilization – Turning 2
19
Integrated Reactive Training
Squat Jump w/Stabilization 1
Squat Jump w/Stabilization 2
Horizontal Jump
w/Stabilization 1
20
Squat Jump
w/Stabilization 3
Horizontal Jump
w/Stabilization 2
Horizontal Jump
w/Stabilization 3
Integrated Reactive Training
Reactive Strength
In reactive-strength training, exercises involve more dynamic eccentric and concentric movement through
a full range of motion in a more repetitive fashion (little time on the ground). The specificity, speed, and
neural demand are also progressed in this level. These exercises are designed to improve dynamic joint
stabilization, eccentric strength, rate of force production, and neuromuscular efficiency of the entire
kinetic chain.
Repeating Squat
Jumps 1
Repeating Squat
Jumps 2
Repeating Butt Kicks 1
Repeating Tuck
Jumps 1
Repeating Butt Kicks 2
Repeating Tuck
Jumps 2
Power Step Ups –
Power Step Ups –
Front 1
Front 2
21
Integrated Reactive Training
Reactive Power
In the power level of reactive training, exercises involve the entire muscle action spectrum and contractionvelocity spectrum used during integrated, functional movements. These exercises are designed to improve
the rate of force production, eccentric strength, reactive strength, reactive joint stabilization, dynamic
neuromuscular efficiency, and optimum force production. They are performed as fast as possible.
Squat Thrusts 1
Squat Thrusts 2
Squat Thrusts 4
22
Squat Thrusts 5
Squat Thrusts 3
Integrated Reactive Training
Proprioceptive Plyometrics Proprioceptive Plyometrics Proprioceptive Plyometrics
Front to Back 1
Front to Back 2
Front to Back 3
Proprioceptive Plyometrics Proprioceptive Plyometrics Proprioceptive Plyometrics
Side to Side 1
Side to Side 2
Side to Side 3
Proprioceptive Plyometrics Proprioceptive Plyometrics Proprioceptive Plyometrics
Diagonal 1
Diagonal 2
Diagonal 3
23
Integrated Reactive Training
Ice Skaters 1
Ice Skaters 2
Integrated Reactive Training Program Design
OPT™ Level
Stabilization
Phase
1
Example Balance Exercises
*0–2 Reactive Stabilization
Sets/Reps
Rest
1–3 x 5–8
0–90 s
2–3 x 8–10
0–60 s
2–3 x 8–12
0–60 s
Box Jump Up w/Stabilization
Box Jump Down w/Stabilization
Squat Jump w/Stabilization
Strength
2, 3, 4
**0–4 Balance Strength
Repeating Squat Jump
Repeating Butt Kicks
Repeating Tuck Jumps
Power Step Ups
Power
5
***0–2 Balance Power
Squat Thrusts
Ice Skaters
Table 1 – Integrated Balance Training Program Design
*Reactive exercises may not be appropriate for an individual in this phase of training if he or she does not possess the appropriate amount of core strength and balance capabilities.
**Due to the goal of certain phases in this level (hypertrophy and maximal strength), reactive training may not be necessary.
***Because one is performing reactive/power exercises in the resistance training portion of this phase of training, separate
reactive exercises may not be necessary.
24
Integrated Reactive Training
Section VII:
Summary
Reactive training is an important component of all integrated training programs. All functional activities
require efficient use of the integrated performance paradigm. Therefore, all programs should include
reactive training to enhance neuromuscular efficiency and prevent injury. The kinetic chain responds to
the imposed demands of training. Less than optimum results will occur if the training program does not
systematically and progressively challenge the neuromuscular system.
25
Integrated Reactive Training
Appendix:
Integrated Reactive
Training Parameters
1. Safety Requirements
a. Proper core and balance capabilities
b. Supportive shoes
c. A resilient training surface
d. A proper program
e. Knowledgeable supervision prior to beginning a reactive training program
2. Training Variables
a. Plane of motion
b. Range of motion
c. External load
d. Amplitude of movement
e. Muscle action
f. Duration
g. Intensity
h. Frequency
i. Contraction velocity
3. Training Progression
a. Simple to complex
b. Stable to unstable
c. Body weight to extra resistance
d. Low load to high load
e. Proper utilization of the plyometric stress continuum
26
Integrated Reactive Training
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