Plyometric training is a type of strengthening exercise usually executed in the form of a jump or repetitive jumps. This type of exercise aids in the elastic/stretch-reflex capacity of muscle tissue, as well as tendon strength, ligament strength, and fascial integrity.
The goal effect of plyometrics is the production of a more powerful athlete.
All event groups can benefit from plyometric work. However, "plyos" are especially suited for sprinters and jumpers. In those particular events, a regularly scheduled presence of plyometric jumps within a training regimen is highly appropriate.
TYPES OF PLYOMETRIC EXERCISE
Plyometrics can be carried out in a variety of ways ranging from lighter intensity impact to extremely high force loads and output.
- Rudimentary Jumps: Done both single or double legged, and multi-directional. These are short distance repetitive jumps or "baby hops". To cover a distance of 20m may take 50 to 60 reps. Rudimentary jumps are also at the lower end of the intensity spectrum.
- Skipping: Skips for height, for distance, and backwards skipping.
- Horizontal Plyometrics or "Bounding": Performed over distances of up to 30m. Bounding is executed with single-leg ground contacts, by hopping or alternating legs, and striving for distance per jump.
- Multiple Throws: Combined jumping & throwing. Done with a medicine ball or shot, and comprised of two-handed throws by underhand motion, back overhead, or push throws from the chest. The athlete does 1 or 2 jumps forward while holding a ball, and throws for height or distance after the last jump. Because of the weight of the ball, multi-throws are a resistance exercise.
- Depth Jumps: (See Figure 1 below) Hopping over hurdles, or up and down onto boxes or raised platforms. Depth jumps are the most intense of all plyometrics and are the mostly vertically oriented. Depth jumps can be done double or single legged.
Jumping movements have phases.
- The flight phase is when the athlete is in the air.
- The support phase is when the athlete is in contact with the ground.
The support phase is divided into two parts:
First is the eccentric or landing phase where the athlete hits the ground, and the joints of the hip, knees, and ankles flex, and the muscles lengthen. Second is the concentric phase or upward movement. Joints extend, muscles contract. This is where the athlete pushes up and launches off the ground.
The amount of flexion in the joints during the eccentric phase depends on the unique demands of each type of plyometric exercise. Generally, the stronger the athlete gets, the less flexion is needed to perform jumping tasks. Some coaches call this "stiffness".
FUNDAMENTALS IN PLYOMETRIC TRAINING
The manner by which an athlete performs plyometrics is significant. Poorly executed jumps can cause injury and fail to yield the intended benefits.
Some crucial training elements are as follows:
- Higher intensity plyometrics: I.e. hurdle hops-- should usually not be done more than once per week to avoid over-training.
- Lower intensity stuff: I.e. skips, rudimentary stuff-- can be done more frequently in a training week.
- Within training sessions, do plyometrics after event specific work or after speed work. Plyometrics tend to fatigue the musculature. One wants to be freshest when working on the runway, block starts, hurdles, or maximum velocity training.
- Surfaces should vary. Grass or artificial turf, or sometimes on the track or runway.
- Adhere to full-footed contacts. The feet should contact the ground either flat or heel-first on each landing.
- If using a double arm-drive on jumps, the arms should be withdrawn back while the athlete is on the descent of the flight phase. In that way when the feet first hit the ground, the arms are behind the athlete--ready to drive forward for the next take off (See figure 1 above).
- Avoid rushing ground contact time. There is a unique amount of time one needs to be on the ground in order to absorb landing and create quality upward force into each takeoff.
- Barriers such as hurdles or boxes should not be too high. The purpose of plyo training is to jump with a large force output which in turn elevates the center of gravity. Barriers that are too high result in survival movements-i.e. lifting the knees into a tuck position to clear boxes or hurdles. Unnecessarily high barriers are also an injury risk.
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Robert Marchetti, a former NCAA Division I track coach at Rider University and Columbia University, is a private track and field coach located in Hamilton, New Jersey. For more information, you can email him at email@example.com. You can visit his website at www.coachup.com/coaches/robertm-4.