Plyometrics, Ground Contact Time, Jump Height and Power Monitoring

When performing movements that require reflexive actions such as depth jumps, the ability to monitor jump height and ground contact time is critical.

Reflexive plyometric actions can stimulate near maximal muscle contractions. However, like voluntary contractions, reflexive actions can fatigue.

When performing reflexive actions, the level of muscle contraction may diminish. This could be due to dampening of the CNS.

As noted in Supertraining, the “rebound” effect plays a critical role in this process. The “rebound” effect is predicated on the fact that after one reflexive contraction, stimulation of similar reflexes become more difficult to elicit over a period of time.

How does this relate to power?

If the reflex begins to dampen, contact times will increase (noted by increases in knee angles) and jump height will be reduced.

However, by using jump height percentage cutoffs as mentioned in our book, you may be able to preserve the reflexive stimulus and monitor CNS fatigue at the same time. If jump height begins to drop drastically, it is possible the CNS is fatiguing from reflexive actions and no longer able to stimulate muscles to their highest degree.

By using percentage drop offs, you can somewhat monitor the CNS. Thus, the potency of the workout may be preserved and the desired stimulus achieved .