The Physiology of Plyometric Training
The term plyometric, as derived from its Greek
roots, means to increase or augment. Such training has been used systematically
in Track & Field by European coaches and athletes for nearly 25 years,
although most American coaches consider it a recent phenomenon. In fact, most of
us have been doing some form of plyometric exercise all our lives. Jumping rope,
playing hopscotch, leaping from the front porch, skipping, and bouncing are all
plyometric movements. Understanding the mechanisms, techniques, and proper
application of plyometric training, however, is essential for it to be properly
integrated into your own system of training.
Plyometrics are exercises that aim to develop explosive ability by conditioning the neuromuscular and elastic characteristics of the muscle. Strictly speaking, plyometric training is a method of training as opposed to a specific set of exercises. One does a certain drill or exercise in a plyometric manner. While there are certain types of drills and exercises that lend themselves easily to plyometric training for Track & Field, the key to their usefulness lies in proper execution and application. When done correctly, plyometrics combine strength and speed by developing the explosive-reactive movements that comprise throwing, sprinting, and jumping.
The main objective of
plyometric training is to produce greater power by training the muscles to
contract more quickly and forcefully from an actively pre-stretched position.
The effectiveness of the exercise relies upon the conditioning of the myotatic, or stretch-reflex, mechanism and the natural elastic
properties of the muscle. Body weight and gravity are used to load elastic
tension within the muscles, which is then released in a muscular contraction
much more forceful than normal. Let's put this in simpler terms. When a muscle
is stretched quickly, it tries to protect itself by contracting. This is called
an eccentric contraction: a contraction where the muscle is forced to lengthen
even though it is trying to shorten itself. (Try making a muscle with your
biceps and then pull your forearm toward the ground.) The counterpart of this is
concentric contraction, where a muscle shortens as it is contracts. This is what
is usually thought of as a muscle contraction. A concentric contraction is much
stronger when it is preceded by an eccentric contraction. In an eccentric
contraction, the muscle reacts very powerfully against the rapid stretching.
This reaction is the stretch-reflex.
The strength of the stretch-reflex is a consequence of how fast a muscle is stretched. When a muscle is stretched quickly, rather than slowly, it is placed under greater tension, storing a greater amount of elastic energy within the muscle. A fundamental principle of plyometric training is that the muscle needs to be pre-stretched quickly. The rate of stretch of the muscle is much more important than the degree of stretch. Consider an example. Suppose that your athletes are doing plyometric exercises in the form of two-legged hopping. To achieve the proper effect, the athletes should jump, land, and rebound with as little time spent on the ground as possible, as opposed to jumping, landing, and then sinking in a full squatted position before attempting to perform the rebound hop. When the eccentric contraction is slowed, the stretch-reflex mechanism is negated and the exercise loses its plyometric quality. Again, the rate of stretch, not the amount of stretch, is the key to training the muscle plyometrically.
Principles of Plyometric Training
Successfully incorporating plyometric exercises
into training programs for Track & Field athletes requires more than knowing
how the muscle is affected during exercise. The best results are achieved when
both coach and athlete understand the role of power in a respective event and
how to integrate and correctly apply plyometrics to an athlete's overall
training. Plyometric training requires the same careful attention, application,
and periodization as training for an individual event. Understand that the goal
of plyometric training is to develop the power and explosive ability that is the
key to success in nearly all Track & Field events.
In constructing a plyometric regimen, the coach must keep in mind the general and specific principles of training. Not adhering to these basic tenets leads to poor results and exposes the athlete to a substantial risk of injury. The universal principles of Track & Field training must be followed in any plyometric program:
Variation is especially important for plyometrics.
Research in strength training shows that the muscular system responds best when
the stimulus is varied over time. The neuromuscular system needs to be shocked
so that it will be forced into adapting. With plyometrics, this means doing
different types of exercises some days or varying numbers of repetitions and
intensity on others.
Beyond the universal principles of training, there are principles specific to plyometrics. As a unique form of exercise emphasizing explosive movement from a pre-loaded and pre-stretched position, plyometrics has its own particular set of considerations to be followed.
The overload of the muscular system by the combination of body weight and gravity requires a basic level of strength to ensure against injury when performing explosive movements. Opinions vary as to the degree of strength needed. Some authorities suggest that the most rigorous forms of plyometrics, such as depth jumps and one-legged box jumps, demand that an athlete be able to squat 150-200% of his or her body weight. This standard would not be met by the great majority of high school athletes. Two rules of thumb apply here. First, athletes should start with the most general and lowest level of plyometric exercises. Low intensity and limited repetitions are suggested for beginners and younger athletes. The coach must also take the athlete's body weight into consideration. The same drill will produce more physical stress upon the heavier athlete. In adolescence, strength in relation to body weight is often poorest among those who are heavier. Second, if the athletes are capable of performing the exercise explosively with correct technique, their strength is probably adequate for the particular exercise. If they are not capable of performing the task properly, or execution breaks down after a few repetitions, then the athletes need to develop greater basic strength before moving on to more advanced drills. This cautionary note is especially appropriate for young athletes, who are usually in a hurry to do the most advanced work first. Remember, the key to plyometric training is technically correct, explosive movement. Doing the exercise improperly only subjects the athlete to the threat of injury.
RAPIDITY OF STRETCH
Muscle exerts maximum tension when it is stretched rapidly. Landing after a two-legged hop produces much greater tension in the quadriceps than simply lowering oneself into a squat from a standing position. The stretch-reflex is utilized best when the involved muscles are stretched quickly.
RATE VS. DEGREE OF STRETCH
A corollary to the previous observation is that the rate of stretch is more important than the degree of stretch. It is better that an athlete do a jumping movement in a quick, bouncy manner rather than slowly sinking to a low squat and then rebounding. Doing jumps slowly is not plyometric and lessens the effect of training.
The goal of plyometric training is to increase power. Therefore, the emphasis should be on reacting explosively immediately upon contract. This is the kinetic moment that you are training. The execution of the exercise should be forceful, but most importantly, done quickly. No gathering should take place before the explosive response.
With any explosive movement, proper technique maximizes improvement and reduces the chance of injury. Sound fundamentals are especially important for younger and less experienced athletes, Correct technique is a good indicator that the athlete is not overstressed by the exercise.
Plyometrics are deceptively exhausting to the muscles. The athlete may even feel more energetic near the end of a workout session than at the beginning. The coach must be aware of the athlete's fatigue. Breakdowns in technique and reduced height and distances in drills indicate fatigue. This is when the exercise or session should end.
CAUTION WITH PLYOMETRICS
Although plyometric training is generally accepted as a training method, it does have detractors. Because of its ballistic nature, there is a risk of injury to the athlete. Plyometrics used improperly can easily lead to injury or over- training. A coach must be especially attentive and careful to ensure that plyometrics are used correctly.
We advocate a conservative approach to the use of plyometrics for high school athletes. Adolescents are susceptible to a variety of injuries. Most high school students are still growing, have softer bone structure than adult athletes, and have not yet developed the absolute strength to handle the more advanced and demanding plyometric drills. Coaches often design programs for their best athletes, forgetting that the capacity of other team members is much less. Your athletes will not benefit from a regimen that they are unable to handle. The age, strength, maturity, and weight of the young athlete must be considered in the construction of a plyometric program.
Good technique is crucial. Demonstrate and dearly explain the proper execution of an exercise before you permit the athlete to begin. Moreover, explain the concept of plyometrics to your athletes. Let them know what the exercise is doing to their bodies and how it is making them better athletes.
Plyometric drills should always be done on a soft level surface, such as grass or padded mats. Concrete, asphalt, or the running track are poor surfaces for such training. Drills should also be done in supportive shoes with good cushioning. Track spikes and throwing shoes should not be worn.
Extra weight, such as ankle weights or weighted vests, should never be used. The aim is to be more explosive. Gravity and speed provide the necessary resistance. Adding weight ruins the plyometric effect by causing the athlete to spend more time on the ground and converts the exercise into a form of conventional strength training.
Last, begin with general exercises at low intensity. Some athletes will take a long time to move on to more advanced and specific plyometrics. Some will never get beyond the most general stage. As a rule, depth jumps (jumps done after dropping from an elevated surface) are discouraged for high school athletes. Any jumping done from boxes should be done only at low heights (12-18 inches) by stronger and more mature athletes.
Constructing a Plyometric Training Program
When integrating plyometrics into your overall training program, it is necessary to assess the fitness of the individual and the events in which he or she participates. The periodization of plyometric training throughout the season and from year to year should also be considered. To do this, you need to understand the different types of plyometric exercises and their specific functions.
TYPES OF PLYOMETRIC EXERCISES
There are three general types of plyometric
exercises: rhythm, power, and speed. Each form develops different qualities of
the neuromuscular system. As such, some exercises are better suited to different
events. Conversely, some events are served well by all three types of
Rhythm plyometrics help develop the coordinated
movement skills required in Track & Field. Their primary purpose is to give
the athlete greater kinesthetic awareness or body sense, coordination, and
rhythm. They promote general athletic ability. All Track & Field athletes
benefit from these drills, but they are especially well-suited for less mature
athletes and those without good natural skills. For example, many young distance
runners have undeveloped strength, rhythm, and coordination. For them, the
greatest contribution of plyometric drills is to increase their coordination and
sense of rhythm. Many young athletes have good ability but simply lack some
basic movement skills because they are growing rapidly.
Rhythm plyometrics are quite useful in developing correct running mechanics. More important, these drills give the young athlete an improved sense of physical awareness, how his or her body moves through space. This applies to all athletes. Rhythm drills for sprinters and hurdlers are crucial to optimal success. Sprinting and hurdling are events where speed and power are expressed through proper technique and rhythm.
Jumpers, too, need rhythm plyometrics. Jumping events involve an explosive movement at the end of a controlled run-up. A smooth rhythm enables the athlete to convert run-up speed into the jump. Even high school throwers need rhythm and coordination. The discus is an event of smooth rhythmic motion building to an explosive release. And shot putters need to have a sense of rhythm with the feet in order to move across the throwing circle and land in a solid power position.
Rhythm plyometric exercises also serve as a bit of physical education. As funding and support for physical education curricula have eroded, many young high school athletes come to sports programs with poor coordination, movement skills, and basic strength. This fact is particularly applicable to a Track & Field team, which usually has greater numbers and variety than most other school sports teams.
Rhythm plyometric drills are mostly simple movements done repeatedly. Generally, they involve segments of the movements athletes use while running, jumping, or throwing. Some common rhythm drills are skipping, running with high knee lift, kicks, running butt kicks, fast feet running, and cariocas. These drills develop the necessary technique and coordination to let speed and power be expressed most efficiently.
The primary goal of plyometric training is to
increase power. The Track & Field athletes that need to stress power
development most are jumpers and throwers, so their training should utilize a
large number of plyometric drills. Throwers should use power plyometrics for the
upper body as well as the lower body.
Although athletes in all events should use power drills in their training at different points in the season, a coach must bear in mind that power movements are physically demanding. Sufficient rest is mandatory, both within and between workouts. During the most competitive part of the season, these exercises should be tapered down. Power exercises for distance runners need to be closely monitored to avoid overtraining during high volume periods.
Power plyometrics emphasize the simultaneous application of maximum strength and quickness. The focus of movement is explosiveness. When doing jump repetitions, for example, the objective is to perform a set of jumps at high intensity, not to continue repetitions past the point of fatigue. Although plyometric training can be used for such purposes, the goal of power drills is not endurance. Explosiveness is greatest when the muscle is warmed and rested. Do a given exercise only to the point where performance declines. It is better to do an extra set of an exercise than to add repetitions that are not done powerfully. Power plyometric drills include a variety of jumping movements ---- hops, bounds, single jumps, and leaps. Upper body exercises include medicine ball throws, pendulum throws, and push- ups. Depth jumps and box jumps are advanced plyometrics, but are risky for most high school athletes.
Speed plyometrics emphasize the speed component of
training. The over- load principle is satisfied in the form of increased speed
rather than force. In other words, movements are performed significantly faster
than normal. The objective of speed-assisted, or over-speed, training is to
force the neuromuscular system to respond more quickly to a stimulus. The
accelerated time frame of the action overloads the system, creating faster than
normal response. This training effect then carries over into increased event
Speed exercises obviously apply to sprint and hurdle events. Maximizing running speed is the key to success in these events. Jumpers, too, rely heavily on sprint speed, most notably long jumpers and pole vaulters. Throwers benefit from speed training through improvements in general quickness. Speed plyometrics for distance runners is beneficial, but one should remember to coach them to be fast distance runners, not sprinters. The focus should be running mechanics as opposed to sprint speed. Many of these drills will be the same as those done for rhythmic development, stressing maximum quickness. Fast skips, arm swings, and butt kicks are a few examples.
Using Plyometrics for Power Endurance
Although the primary goal of plyometrics is to
develop explosiveness, athletes also gain by training for power-endurance. Long
sprinters and those who compete in multiple events need to develop the capacity
to be explosive repeatedly. Further, all athletes gain from building a
foundation of strength and sub-maximal power. Such preparation prevents injuries
and allows for greater intensity and quality in training.
Generally, power plyometrics should be performed with 4-8 repetitions at maximal effort. Exceeding that number diminishes the specificity of the exercise for explosiveness. With a greater number of repetitions, however, a power-endurance effect is achieved. It is not too unlike speed-endurance running for sprinters and middle-distance runners. Where sprinters train to maintain speed over distance, athletes can also train to be powerful over time. Repetitions from 8 to 20 or more and distances from 40 to 150m fall in the endurance category.
There are other benefits to the use of plyometrics for power-endurance. Multiple repetitions of low stress exercises often serve as a good introduction to plyometric training. Young athletes can learn the jumping movements and techniques more easily when they can focus solely on the movement without having to concentrate on the explosive element. The conditioning effect of these multiple repetitions also builds strength in your athletes and prevents injury as the intensity of the exercise increases. Finally, as a practical consideration for the high school coach, somewhat less supervision is needed to accommodate a fairly large portion of your team.
INDIVIDUAL PLYOMETRIC EXERCISES
As with any training program, there is no single
regimen of plyometric exercise which will guarantee optimum performance from
your athletes. The particular exercise is often much less important than how it
is executed. In fact, the same basic movement performed differently can develop
rhythm, power, or speed. Consider skipping, for example. Remember, the
successful application of plyometrics hinges on properly training the stretch
reflex and elastic qualities of the muscles involved. The emphasis is upon
explosive reaction in response to the active loading of the
Many exercises can be made plyometric. Many coaches will discover a drill that seems especially well suited to their athletes, facilities, and environment. The following listing and description of various plyometric exercises is not intended to be exhaustive. These drills are strongly recommended, however, and should be more than adequate for high school athletes.
Rhythm Plyometrics Drills
High Knee Running
Rhythm Jump Run-Ups
POWER PLYOMETRIC DRILLS
Note on Power Plyometric Drills. Power exercises are the bulk of what is
commonly called plyometrics. They involve explosive movement with high levels of
intensity and effort. When introducing power drills to athletes, the coach must
take great care to avoid injury. This is especially true with younger and less
developed athletes. Do not force the athlete to do power exercises that they
cannot perform correctly. Two general rules apply when determining the fitness
of an athlete for a particular exercise. One, the athlete should be able to
perform the drill properly as rhythm drill first. Two, the athlete should be
able to maintain correct technique when the drill is performed as a power
exercise. Improper execution is a strong signal that the athlete is not yet
prepared for a given power plyometric exercise.
Double and Single Leg Hops
Standing Triple Jumps
Medicine Ball Throws
FROM: AAF/CIF COACHING MANUAL