Unfortunately, while most athletes today are familiar with the term plyometrics, few fully understand the principles involved. Simply stated, plyometrics involves maximal muscle contractions at the highest velocity possible. By using this type of training properly, physical performance can be improved.

Research tells us that when elite athletes sprint, jump or kick, they spend less time in contact with the ground, but impart an equal or greater amount of force into the ground than less skilled athletes. The true purpose of plyometric training is to decrease the ground contact time of an athlete during performance. Ground contact time can simply be seen as the phase of time that elapses while the eccentric contraction (stretch) of a muscle group is reversed and the concentric contraction (contract) of that group begins. So if you look at a long jumper, this phase would be seen as the time it takes when his plant foot hits the ground until he pushes off and leaves the ground for the jump. If he can make that phase happen faster and more powerfully, he will jump farther. This phase of movement is where all plyometric activities are focused. Once believed to be genetic in nature, research indicates that this period of time can be reduced. By doing this, we can increase the speed and power of movement, which translates directly into higher velocities for sprinting, jumping, punching and kicking.

Plyometrics address Newton's third law of physics that "to every action there is an equal and opposite reaction". As the athlete's body is directed into the ground, the forces are used by the muscles to propel themselves for running and jumping. This does depend on the muscle and tendon's capacity to store this force as elastic energy and then transmit that force back into the resultant muscular contraction. When a muscle is stretched, the elastic components are lengthened and when this stored elastic energy is recovered by the muscle the resultant concentric contraction is enhanced. The faster the velocity of the stretch is applied, the more ability the muscle has to develop force.

Specifically, plyometrics target a muscle's fast twitch fibers. These fibers are in charge of speed and higher power production. Since most sports focus around the need for explosive movements, these are the type of fibers you should be training.

Before ever starting a plyometric program, you must assess your previous training experience, age, physical maturity and conditioning, flexibility and strength. The more experienced an athlete is with training, the younger he can begin plyometrics and the more intense the exercises can be. Prepubescent athletes should not perform high shock activities, but low intensity plyometrics should be fine. Full range of motion is a prerequisite for performing plyometrics. Athletes must also have a good strength base before performing plyometrics. The athlete should maintain a strength program for a few months before beginning plyometrics. During these strength activities the trainer should focus on functional strength activities that use the core musculature addressed during the plyometric activity.

Before a plyometric training workout, the athlete should prepare with a dynamic warmup routine. The routine should include at least 15 minutes of calisthenics and light skipping and sprinting motions. This warmup will enhance the muscle's ability to perform the plyometrics, and decrease the chances of injury. The programs should include a wide range of different jumps and explosive movements to decrease plateauing during training. Recovery between workouts should be 48 to 72 hours, resulting in 2 plyometric workouts per week. The volume is determined by the number of foot contacts performed per session. The intensity and volume of the exercises should have an inverse relationship during your training programs. This means that if the stress of the exercise is very high, the number of repetitions should be kept low.

Try This at the Gym: A great example of a beginner plyometric workout is one I got from an Olympic coach that is sure to make you more explosive. Jump in place as many times as you can for fifteen seconds. Keep your body straight and pull your toes up after every short jump. Let your arms help to propel your body up and down. Count the number of contacts you can make in fifteen seconds, and try to beat that mark for 6 sets. Rest 30 seconds in between each set. Try it before your workouts 3 times per week and see if you can increase the contact number over a few weeks. If you do, you have made yourself more powerful using plyometrics!

-Bill Parisi, Parisi Speed School

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