Plyometric Training: Very Important For Speed Development

From a physiological basis, if a muscle is pre-stretched or made to build up high tension, it will contract with a much greater force.  Plyometrics make use of this factor.  The key in performing plyometrics is that the response from the ground must be immediate otherwise the exercise turns into a concentric contraction and does not involve the stretch reflex.

The physiological theory behind plyometric training is to develop efficiency in the stretch/shortening cycle of muscle action.  During the stretch of muscle action, a greater amount, a greater amount of elastic energy is stored in that muscle.  This elastic energy is then reused in the shortening muscle action that follows, to make it stronger.  The key is to shorten the switching time i.e. the time it takes for the muscle to change from lengthening phase to the shortening work phase.  The fundamental  principle of plyometric training is that it is the rate, not the magnitude of the stretch that determines the utilization of elastic energy and the transfer of chemical energy into mechanical work.  This means that this type of training does not need to be done in high volumes but instead it needs to be performed at manageable intensities of impacts. 

What to Watch for During Plyometric Exercises

1. If slow switching from eccentric to concentric work is observed, then eccentric strength levels are inadequate.  Quick contacts displaying a rapid change of direction are essential.

2. The foot strike must be on the full foot in order for the foot to help absorb the shock.  It is incorrect to land completely on the heel or the ball of the foot. 

3. The shock of the landing should be absorbed by a combination of the ankle, knee and hip joints working together that will absorb the initial shock of landing and transfer that force throughout the body's muscles. 

Progression in plyometric training should be carefully monitored.  This type of training should be done no more than twice per week with low volume of repetitions.