Essentially plyometrics are a set of explosive exercises designed specifically to help muscles reach their maximum potential in as short a time as possible. Since speed and strength are an integral component of sports fitness, the combination of speed and strength, also known as power, is important. Plyometrics is a way of enhancing athletic performance by training for power or explosivness by methods of jumping or hopping. This method of training seeks to enhance the explosive reation of the athlete through powerful muscular contractions as a result of rapid eccentric contractions.

Specificity of Training

The golden rule of any conditioning program is specificity of training. This simple means that any movement performed in training should match as closely as possible the movements encountered in competiton.

If you are a basketball player, or a volleyball player, where vertical jump height is important, then drop jumping or box jumping may be the right exercise for you. However, if you are shot putter, throw the discus or javelin, or even pitch a baseball, then upper body plyometrics is far more appropriate.

Plyometric Exercises

The following are examples of some lower and upper body plyometric exercises:

Lower Body Exercises

Drop Jumping - This exercise involves the athlete dropping (not jumping) to the ground from a raised platform or box, and then immediately jumping up. The drop down gives a pre-stretch to the leg muscles and the explosive drive upward the secondary concentric contraction. The exercise will be more effective the shorter the time the feet are in contact with the ground. The loading in this exercise is governed by the height of the drop which should be in the region of 30-80 cm/ 12-31 inches. Drop jumping is a relatively high impact form of plyometric training and would normally be introduced after the athlete had become accustomed to lower impact activities, shuch as two-footed jumping on the spot.

Bounding and Hurdling - If forward motion is more the name of your game, try some bounding. This is a form of plyometric training, where over sized strides are used in the running action and extra time spent in the air. Two-legged bounds reduces the impact to be endured, but to increase the intensity on legged bounding, or hopping, can be used. Bounding upstairs is a useful way to work on both the vertical and horizontal aspects of the running action. Multiple jumps over a series of obstacles, like hurdles is a valuable drill for athletes training for sprinting or jumping events.

These exercises are all aimed at the lower body, but a variety of drills can be used to make the upper body more explosive.

Upper Body Exercises

Push Ups and Hand Claps - Push ups with a hand clap in between is a particularly vigorous way to condition the arms and chest. The pre-stretch takes place as the hands arrive back on the ground and the chest sinks. This is followed quickly by the explosive upward action. Once again, to get the best training effect keep the time in contact with the ground to a minimum.

Medicine Ball Toss - Another means of increasing upper body strength popular with throwers is to lie on the ground face up. A partner then drops a medicine ball down toward the chest of the athlete, who catches the ball (pre-stretch) and immediately throws it back. This is another high-intensity exercise and should only be used after some basic conditioning.

An excellent book on the subject of plyometrics, featuring a wide range of exercises, is "Plyometrics for Fitness and Peak Performance," by Donald A. Chu, Ph.D. and Raymond Signor.

Planning a Plyometric Session

The choice of exercises within a session and their order should be planned. A training session could:

• Begin with exercises that are fast, explosive and designed for developing elastic strength (low hurdle jumps, low drop jumps).
• Work through exercises that develop concentric strength (standing long jumps, high hurdle jumps).
• Finish with training for eccentric strength (high box jumps).

An alternative session could consist of:

• Begin with low hurdle jumps.
• Progress to bounding and hopping.
• Continue with steps or box work.
• Finish with a medicine ball workout for abdominals and the upper body.

Warm Up

A thorough warm-up is essential prior to plyometric training. Attention should be given to some light running or jogging, stretching (static and ballistic), striding and general mobility movements especially along the joints involved in the planned plyometric session. A cool down should follow each workout.

How Many Reps?

It is wise not to perform too many repetitions in any one session - since it is quality that is important. Emphasis speed and power, rather than endurance. Split the work into sets with plenty of recovery time in between the sets.

Where to Do It - What to Wear

For bounding exercises use surfaces such as grass or a resilient type surface. Avoid cement floors, because of the lack of cushioning. Choose well-cushioned shoes that are stable and can absorb some impact and shock.

All athletes should undergo some general orthopedic screening before engaging in plyometric training.

Conditioning for Plyometric Training

Higher than normal forces are placed on the muscuosketal system during plyometric training, so it is important for all athletes to have a good sound base of general strength and endurance.

Most experts state that a thorough grounding in weight training is essential before you start plyometrics. It has been suggested that an athlete be able to squat twice their body weight before attempting depth jumps. However, less intensive plyometric exercises can be incorporated into general circuit and weight training during the early stages of training so as to progressively condition the athlete. Simple plyometric drills such as skipping, hopping, and bounding should be introduced first. More demanding exercises such as flying start single leg hops and depth jumps should be limited to thoroughly conditioned athletes.

Final Thoughts

Plyometric type exercises have been used successfully by many ahletes as a method of training to enchance power. In order to realize the potential benefits of plyometric training, the stretch-shortening cycle must be invoked. This requires careful attention to the techniques used during the drill or exercise. The rate of stretch rather than the magnitude of stretch is of primary importance in plyometric training.

In addition, the coupling time, or ground contact time must be as short as possible. The challenge to the coach or athlete is to select or create an exercise that is specific to the event or sport that involves the correct muscular action. As long as you remember specificity, and to ensure there is a pre-stretch first, then the only limit is your imagination.