In The Beginning
Plyometrics were developed in Eastern Europe for Olympic competitors. The words plyo and metrics are Latin for "measurable increases." All plyometric exercises are done quickly and correctly. There are never any shortcuts. Every action is performed with the intent to have a muscle reach full movement as quickly as possible. If you do plyometrics consistently and correctly you will see results.
In the 1920s, the sport of track and field was the first to employ a systematic method of using plyometric-training methods. By the 1970s this methods of power development was being used by other sports that required explosive power for successful competition.
What Are Plyometrics?
Speed and strength are integral components of fitness found in varying degrees in virtually all athletic movements. Simply put the combination of speed and strength is power. For many years coaches and athletes have sought to improve power in order to enhance performance. Throughout this century and no doubt long before, jumping, bounding and hopping exercises have been used in various ways to enhance athletic performance.
Plyometrics can best be described as "explosive-reactive" power training. This type of training involves powerful muscular contractions in response to a rapid stretching of the involved musculature. These powerful contractions are not a pure muscular event; they have an extremely high degree of central nervous system involvement. The event is a neuromuscular event! It is a combination of an involuntary reflex (i.e. a neural event), which is then followed by a fast muscular contraction (i.e. voluntary muscular event). Sound complicated? Well, it's really not. We all have seen it, experienced it and continue to use this type of "reactive" movement pattern to develop power. We all do it everyday.
The maximum force that a muscle can develop is attained during a rapid eccentric contraction. However, it should be realized that muscles seldom perform one type of contraction in isolation during athletic movements. When a concentric contraction occurs (muscle shortens) immediately following an eccentric contraction (muscle lengthens) then the force generated can be dramatically increased. If a muscle is stretched, much of the energy required to stretch it is lost as heat, but some of this energy can be stored by the elastic components of the muscle. This stored energy is available to the muscle only during a subsequent contraction. It is important to realize that this energy boost is lost if the eccentric Contraction is not followed immediately by a concentric contraction. To express this greater force the muscle must contract within the shortest time possible. This whole process is frequently called the stretch shortening cycle and is the underlying mechanism of plyometric training.
Choose the method to fit the sport
The golden rule of any conditioning program is specificity. This means that the movement you perform in training should match, as closely as possible, the movements encountered during competition. If you are a volleyball player interested in increasing vertical jump height, then drop jumping or box jumping may be the right plyometric exercise for you.
What not to do
Inappropriate use of plyometric training has been associated with various forms of "over-use" injuries, especially in the lower extremities (e.g. patellar and Achilles tendinitis and plantar faciitis). It is important to be in good physical shape in order to perform plyometric exercises.This type of training, especially when done at a very high intensity, is a high-risk endeavor (i.e. high returns but at high risk). Like any other high-risk maneuver, high intensity plyometrics should not designed or performed without the supervision of a professional overseeing the training, and response, to the exercise protocol.