Plyometric exercises are specialized and very intense training techniques, which are used to develop muscular power, referring to the relationship between strength and speed. Plyometrics include any exercise where the muscle is contracted eccentrically (stretched) then immediately moved concentrically (contracted). The ability to generate a force in a short time allows for athletic movements beyond what strength alone will allow. For a muscle to cause movement, it contracts concentrically. Various muscles have different maximum amounts of power with which they can contract. However, if the muscle is lengthened (eccentric contraction) just prior to the contraction, it will actually produce more power. In order to produce this effect, the time between the eccentric contraction and the concentric contraction must be very short.
An example of a plyometric exercise is push-ups with a clap in between each push-up. In this case, the pectoral muscles are elongated and loaded by the downward force of your body, stretching eccentrically, then immediately contracted to push the body back up, stretching concentrically. The clap push-up, as opposed to a normal push-up, ensures that there is only a short amount of time between the eccentric and concentric contractions of the muscle. Examples of lower body plyometrics include depth jumps, multiple jumps, marches and lateral jumps, often involving boxes or platforms, and weight vests. Mid-section plyometrics include the broomstick twist, and twists, side-throws and sit-ups using a medicine ball. Upper body plyometrics involve medicine ball exercises and different types of push-ups.
The word "plyometrics" has been around since the 1960s but athletes were using the technique many years before the term was coined. Some of the exercises commonly used today include jumping off a box and rebounding off the floor onto another, higher box while either carrying weights, or more often wearing a weight vest.
While plyometrics have been shown to increase power, experts' opinions vary regarding the safety of these exercises. Many well-respected fitness experts argue the benefits and effectiveness of plyometric exercise. However, there are others who strongly deny these benefits and argue that plyometric exercises are extremely unsafe and the risk of injury far outweighs any potential benefits. Most experts state that a thorough grounding in weight-training is essential before starting plyometrics.

Related Terms

Plyometric exercises, power training, stretch reflex, stretch-shortening cycle.