Plyometric training is an exercise program of explosive movements designed to develop greater muscular power. Strength-training, aerobic exercises, and stretching alone usually will not achieve that. Conversely, plyometric exercises can increase muscle power output without necessarily increasing maximum strength and aerobic capacity. The exercises are generally used as a component of a broader workout program for improved athletic performance.

Muscle movement occurs in a muscle when the fibers contract. There is, however, a maximum force at which some muscles can concentrically contract. Plyometric exercises are used to alter that muscular and neurological chemistry to improve the ability to convert strength to speed in the shortest amount of time.

In a plyometric exercise, such as a hand-clap push-up, the chest muscle is lengthened with the downward force of the body. Immediately before the recoil of the chest muscle, it is thought that the greater force needed for the concentric contraction will be produced through the storage of elastic energy — in much the same way that a rubber band snaps back after being stretched out. That elastic energy, however, dissipates quickly. To be effective, the transition time between eccentric contraction and concentric contraction, called the amortization phase, must be quite short. This process is called the stretch shortening cycle — one of the key bio-mechanisms of plyometric training.

Further, a Plyometric exercise affects the muscle’s stretch reflex, which helps protect a muscle against unnecessary injury. Two neural receptors of the muscle are responsible for the stretch reflex — the muscle spindles, which lie parallel to the muscle fiber, and the Golgi Tendon Organ, which is located deep within the junction of the muscle and tendon. Working together, the Golgi Tendon Organ relaxes the muscle in a stretch when it senses too much force on the muscle while the muscle spindle contracts the muscle to protect it from being stretched out too far.

At the end of a rapid eccentric contraction, the muscle has reached a great length at a high velocity. That may cause the muscle spindle to react and enact a powerful stretch reflex, thereby further enhancing the power of the concentric contraction to follow. That sensitivity of the muscle spindle to velocity is another reason why the amortization phase must be extremely brief for a plyometric effect to be successful.

Plyometric exercises are commonly classified into four groups. These groups include place jumps, short bounding exercises, extended bouncing exercises, and depth jumps. A typical training program would involve two to three days per week of some type of plyometric exercises.

Generally, plyometric exercises are not for everyone. Plyometric training usually is recommended for well-conditioned athletes who are familiar with plyometric exercise techniques and safety considerations. Aspects of plyometric training can, however, be beneficial for most exercisers as long as common sense and safety issues are followed to prevent injury.

A person typically should perform plyometric exercises on soft or cushioned surfaces only while using footwear with plenty of cushion. Exercisers generally should thoroughly warm up before beginning. A person should begin slowly with small jumps and land softly to absorb shock. Plyometric repetitions usually should be no higher than 75 to 100 reps. To avoid muscular degeneration, a person should maintain good nutrition and allow plenty of rest between plyometric sessions.