What Is Plyometrics

Plyometrics is an excellent way for both conditioned athletes and those of a good level of fitness to increase and develop their jumping, sprinting and explosive power.

During the early 70's Eastern European countries were producing great improvements in a number of individual based sports such as track and field, weight lifting and gymnastics. The secret behind these successes lay in their training - explosive movements using a combination of muscle contractions to improve the athletes explosive power. This form of training was called Plyometrics, from the Latin "plyo + metrics" meaning measurable increases.

Plyometrics Defined

The underlying principle of plyometric training is the stretch-shortening cycle, a term and training method used prior to the formation of plyometric training as we see it today. As a muscle stretches and contracts eccentrically (lengthens while it contracts) it produces elastic energy, which it can store. If the muscle then contracts concentrically (shortens while it contracts) this elastic energy can be used to increase the force of the contraction.

If an athlete jumps vertically they will lower down just before the jump, or if a boxer wants to throw a hard punch, they will rotate around and back prior to exploding forward. Lowering the center of gravity, whilst stretching the working muscle groups allowing the athlete to contract more forcefully for the jump, likewise the rotation and contraction prior to throwing the punch will generate more force.

A muscle stretched before it contracts will contract much more forcefully, resulting in a greater jump - throw or faster acceleration.

Maximum strength takes generally 0.5 to 0.7 seconds to produce, however most sporting actions will occur far quicker than this, your aim when performing plyometrics is to produce highest possible force in the shortest possible time.

Plyometric training will increase stretch loads on the working muscles. Just like weight training whereby your muscles will soon become stronger, plyometrics will enable your muscles to become more tolerant to the increase loads of the stretch-shortening cycle, resulting in quicker and more explosive contractions.

As your muscles become better adapted to storing elastic energy, it can transfer from the eccentric or stretching phase to the concentric or lengthening phase more rapidly.

Concentric Contraction
An isotonic muscle contraction, where a muscle contracts or shortens.

Eccentric Contraction
Muscle lengthens while maintaining tension.

Isometric Exercise
Muscular contraction where muscle maintains a constant length and joints do not move. These exercises are usually performed against a wall or other immovable object.

CONCENTRIC THE BICEPS BECOME PEAKED	ECCENTRIC LOWERING DOWN UNDER CONTROL	ISOMETRIC BICEPS BEING STRETCHED

Plyometric exercises, must involve movement, followed by an eccentric contraction, in order to stimulate the muscles proprioceptors so that elastic loading can take place in order for a rebound reaction.