Plyometrics and Plyometric Exercises, By: Brad Walker

Plyometric Exercises are great
for Injury Prevention and Rehabilitation!

What are Plyometric Exercises?
In the simplest of terms, plyometrics are exercises that involve a jumping movement. For example, skipping, bounding, jumping rope, hopping, lunges, jump squats, and clap push-ups are all examples of plyometric exercises.

However, for a more detailed definition we need some back ground information about muscle contractions. Muscles contract in one of three ways:

1. An Eccentric muscle contraction occurs when your muscle contracts and lengthens at the same time. An example of an eccentric muscle contraction is lowering yourself from a chin-up position. The bicep (upper arm) muscle contracts and lengthens as you lower yourself from the chin-up bar.

2. A Concentric muscle contraction occurs when your muscle contracts and shortens at the same time. An example of a concentric muscle contraction is lifting yourself into a chin-up position. The bicep muscle contracts and shortens as you raise yourself up to the chin-up bar.

3. An Isometric muscle contraction occurs when your muscle contracts, but does not change in length. An example of an isometric muscle contraction is hanging from a chin-up bar with your arms bent at 90 degrees. The bicep muscle contracts, but does not change in length because you're not moving up or down.

Getting back to the formal definition, a plyometric exercise is an exercise in which an eccentric muscle contraction is quickly followed by a concentric muscle contraction. In other words, when a muscle is rapidly contracted and lengthened, and then immediately followed with a further contraction and shortening, this is a plyometric exercise. This process of contract-lengthen, contract-shorten is often referred to as the stretch - shortening cycle.

Here's another example of a plyometric exercise. Consider the simple act of jumping off a step, landing on the ground with both feet, and then jumping forward. All done in one swift movement.

When you jump off the step and land on the ground, the muscles in your legs contract eccentrically to slow your body down. Then, when you jump forward your muscles contract concentrically to spring you off the ground. This is a classic example of a plyometric exercise.

Why are Plyometric Exercises Important for Injury Prevention?
Plyometrics are often used by athletes to develop power for their chosen sport, and a lot has been written about how to accomplish this, but few people realize how important plyometrics can be in aiding injury prevention.

Essentially, plyometric exercises force the muscle to contract rapidly from a full stretch position. This is the position in which muscles tend to be at their weakest point. By conditioning the muscle at its weakest point, (full stretch) it is better prepared to handle this type of stress in a real or game environment.

Why are Plyometric Exercises Important for Injury Rehabilitation?
Most injury rehabilitation programs fail to realize that an eccentric muscle contraction can be up to three times more forceful than a concentric muscle contraction. This is why plyometric exercises are important in the final stage of rehabilitation, to condition the muscles to handle the added strain of eccentric contractions.

Neglecting this final stage of the rehabilitation process can often lead to re-injury, because the muscles have not been conditioned to cope with the added force of eccentric muscle contractions.

Caution, Caution, Caution!
Plyometrics are NOT for everyone. Plyometric exercises are not for the amateur and they're not for the weekend warrior. They are an advanced form of athletic conditioning and can place a massive strain on un-conditioned muscles, joints and bones.

Plyometric exercises should only be used by well conditioned athletes and preferably under the supervision of a professional sports coach. If you are thinking about adding plyometrics to your regular training regime, please take careful note of the following precautions.

• Intense, repetitive plyometric exercises should not be used by children or teenagers who are still growing.

• A solid base of muscular strength and endurance should be developed before starting a plyometrics program. In fact Chris from www.better-body.com recommends; "It's a good rule of thumb that before you start using any plyometric exercises you should be able to squat at least 1.5 times your own body weight, and then focus on developing core strength."

A thorough warm up is essential to ensure you're ready for the intensity of plyometric exercises. For more information on warming up, visit http://www.thestretchinghandbook.com/archives/warm-up.html

• Do not perform plyometric exercises on concrete, asphalt or other hard surfaces. Grass is one of the best surfaces for plyometric exercises.

• Technique is important. As soon as you feel yourself getting tired or your form starts to deteriorate, back off.

• Don't over do it. Plyometrics are very intense. Give yourself plenty of rest between sessions, and don't do plyometric exercises two days in a row.