PRINCIPLES OF PLYOMETRIC TRAINING

Plyometric exercises are mostly jump-related exercises that focus on training the muscles to produce the
maximum amount of force in the shortest amount of time. Plyometric training involves performing a
countermovement, which emphasizes the stretch-shortening cycle (SSC). In the SSC, a muscle is loaded
with elastic energy during the eccentric phase (during the lowering phase of a squat for example) when it
lengthens, which allows it to contract more forcefully during the concentric (shortening) phase.

As a simple example, consider the vertical jump test described in Chapter 1. Before jumping the athlete is
allowed to perform a countermovement (Figure 1.10b and Figure 7.2 below) from a standing position.

Figure 7.2

During the countermovement, the player squats down- which lengthens the quadriceps and gluteal
muscles in the legs, and loads them with elastic energy. This elastic energy then contributes to a more
forceful contraction when these muscles extend the knees and hips prior to taking off.

There is a slight pause at the bottom of the countermovement when the player transitions from a
downward movement into jumping upwards. This pause is known as the amortization phase and is very
important to the success of the jump. If the amortization phase is too long, then the elastic energy stored