Plyometrics

Plyometrics, also known as jump training or plyos, are exercises in which muscles exert maximum force in short intervals of time, with the goal of increasing power (speed-strength).

This training focuses on learning to move from a muscle extension to a contraction in a rapid or "explosive" manner, such as in specialized repeated jumping.

[1] Plyometrics are primarily used by athletes, especially martial artists, sprinters and high jumpers,[2] to improve performance,[3] and are used in the fitness field to a much lesser degree.

[4] Plyometrics include explosive exercises to activate the quick response and elastic properties of the major muscles.

[6] The term "plyometrics" was coined by Fred Wilt after watching Soviet athletes prepare for their events in track and field.

The second version of plyometrics, seen to a greater extent in the United States, involves any form of jump regardless of execution time.

The term plyometric is a combination of Greek words πλείων (pleíōn), which means "more", and μέτρον (métron) "measure".

[11][12][13] Fred Wilt, a former US Olympic long-distance runner, is credited with coining the term plyometrics after watching the Russians execute jumps in their warm-ups prior to their event in track and field.

He could not understand why the Russians were doing all of these jumps while the Americans were doing multiple static stretches, but he firmly believed it was one of the reasons why they were so successful in many events.

When Fred Wilt learned of the work being done by Michael Yessis in the field of Russian training methods, they quickly teamed up to help disseminate information on plyometrics.

In collaboration with Yessis who visited and worked with Verkhoshansky[14] in the Soviet Union in the early 1980s, plyometrics was gradually disseminated in the US.

Yessis brought this information on plyometrics back to the US and in the following years was able to create even more ways of using this method to train and improve explosive power.

In the depth jump, the athlete experiences a shock on landing in which the hip, knee, and ankle extensor muscles undergo a powerful eccentric contraction.

To execute the depth jump, the athlete stands on a raised platform, usually not greater than 20–30 inches (51–76 cm) high, and then steps out and drops down in a vertical pathway to make contact with the floor.

This tension, which is potential force, is then given back in the return movement when the muscular contractions switch to the concentric or shortening regime.

The exact platform height used by most athletes in the depth jump should be less than 30 inches (76 cm) in the early stages of training.

In essence, the athlete goes into a slight squat (crouch) upon landing in which the hip, knee, and ankle joints flex.

These jumps are effective for athletes who execute skills in their sport that do not require explosive type muscular contractions.

An example is long-distance running in which the runners execute repeat actions of 20 to 30 consecutive jumps and other cyclic-type activities such as leaping for multiple repetitions.

In essence, they are effective in the early stages of learning how to do plyometric exercises and for preparing the muscles for explosive or quick jumps.

The athlete usually sinks (drops) too low which takes too long to make the transition from the eccentric to the concentric contraction.

Studies have been conducted testing ten various plyometric exercises on overall performance during jumping examined by EMG, power, and ground reaction force (GRF).

This shows that the plyometric exercises themselves had a greater effect in the decrease in power output rather than the type of weight training.

Chu (1998) recommends that a participant be able to perform 50 repetitions of the squat exercise at 60% of his or her body weight before doing plyometrics.

[26] Proprioception is an important component of balance, coordination and agility, which is also required for safe performance of plyometric exercises.

Further safety considerations include: Plyometrics are not inherently dangerous, but the highly focused and intense movements used in repetition increase the potential level of stress on joints and musculo-tendonous units.

Many professional and Olympic athletes use plyometrics training to improve muscular strength and jumping abilities which therefore increases their power.

Another benefit of plyometrics is that you can vary your level of intensity which means anyone looking to improve strength and jumping training can be involved regardless of fitness.

In addition, a regular weight lifting exercise is sometimes given a plyometric component, such as is found in a loaded jump squat.

It typically makes more intense demands on the legs than bilateral plyometric training and can be used to further enhance explosive power.