Plyometrics is not a new concept. It has been used for improving performance for years. It is just recently that it has gained wide attention. The word Plyometrics has been in use since the 1960's.
Plyometric training is based on using movements that are similar to the type of movement that would be done in a particular sport or activity to improve performance. Several studies have demonstrated that a combination of plyometrics and weight training is far more effective in improving speed and strength (power).
Plyometrics, employed to develop power and explosiveness, uses the Stretch-Shorten Cycle (SSC). The whole idea is to develop the most amount of force in the shortest possible time. When a muscle is flexed or shortened, it's under tension and will react with a more powerful and explosive contraction due to stored elastic energy. Unlike most other aerobic exercises, gravity becomes a major factor in the workout routine. Strength and flexibility are prerequisites for Plyometric training. The laws of Physics apply. A one g force is equal to your weight. Two or more g's of force may be exerted by an individual during a jump. For example, a 250 pound (114 kg) individual would subject forces equal to or greater than 500 lbs (227 kg) of pressure on hip, knee and ankle joints. A 100 (45 kg) pound person would experience force equal to or greater than 200 pounds (91 kg). It's obvious that too much plyometric training can be damaging to joints as is the case with all types of exercise.
As is the case in all other types of training, technique is the key. In this case, as they say in piloting, landing is the most important of all. When the body meets the ground is where the potential for damage is highest. Land like a cat. The joints should not be stiff. Allow the legs to act as a shock absorber. The best way to land is to pretend that you are jumping off of a step behind someone and you don't want them to hear you land. This is true for running as well. Use the body's natural ability the absorb shock. If you hear a lot of noise when you run or land from a jump, remember that energy was used to create that noise and your body was the instrument. Keep it quiet. Some people advocate landing on the ball of the foot and some on the full foot. Either way, energy must smoothly and evenly transfer up the leg. The use of arms in a jump has been shown to contribute up to 10% of the jump results.
When a muscle is eccentrically contracted (stretched or elongated) and then subsequently concentrically contracted (flexed or shortened) the speed of the contraction is increased thereby creating a more powerful contraction similar to a stretched rubber band. In the real world, muscles undergo a more complex movement involving muscle groups and greater neural interaction than what can be achieved in regular weight training.
There is some controversy as to whether plyometrics are safe. The question is answered by moderation. All types of exercise can be damaging if done to excess or just trying to do too much too soon. Start out small. Use low jumps until your body becomes adapted for balance and timing. Unfortunately the stories come from people just not willing to give their body a break, rest in between workouts and vary their workouts. Running everyday is not good either. Unless you have joint problems, Plyometrics is as safe as any other exercise and provides another area of physical training.
- Improves muscle response time
- Increases muscle performance
- Tones muscles
- Improved balance and posture
- Increases flexibility, reducing capability for injury