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KINECTED: Hazards in plyometric training

There is probably no other form of athletic training that is as effective, yet misunderstood as plyometric training.
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There is probably no other form of athletic training that is as effective, yet misunderstood as plyometric training.

It was used extensively in eastern-block countries for decades, and helped improve the power and speed of their athletes dramatically. Now it is a mainstay of athletic training at the elite level all over the world. It improves many athletic variables, including throwing, kicking and shooting power, first-step quickness, sprinting speed, and jump height.

Some examples of plyometric exercises are hopping, bounding, push-ups with a clap in between, and depth-jumps.

Despite being an effective and safe exercise when used properly, there are possible risks when undertaking plyometric training, and care must be taken to learn the fundamentals before attempting advanced  training. These days it is done in aerobic classes and boot camp classes, but participants are not usually strong enough for the higher-demand exercises and not usually monitored closely for their technique, especially when it is used more as an aerobic exercise as part of a circuit.

Another key point is that plyometric training should only be undertaken if it’s applicable to the sport. Most sports utilize power and speed, but there are some that don’t, such as curling, equestrian, shooting and archery, among some others.

Plyometric comes from the Greek word pleythyein (meaning to augment or increase). It takes advantage of what’s called the “myotatic reflex” and the “stretch-shortening” cycle of muscle contraction. It is similar to the reflex elicited when your doctor taps your knee tendon with the rubber hammer, causing your leg to kick forward. You can make use of that reflex during plyometric training by voluntarily contracting the muscle quickly (milliseconds) after it is stretched.

One example of a plyometric exercise is to jump, and just after landing, quickly explode into another jump. This will generate and extra boost from the tendon-muscle reflex, which can produce a higher jump and more power in the muscles being trained.

Hopping exercises generally create a low to moderate load on the muscles and are fairly safe for most active people, especially those involved in athletics. But drop-jumps (stepping off a one-foot or two-foot high platform, landing and then jumping in the air) are extremely taxing on the central nervous system and impose significant stress on the muscles and tendons. Athletes doing drop-jumps need to be extremely strong and have impeccable technique while performing the exercises, otherwise injuries will likely result.

Some important guidelines for plyometrics: the training regimen is similar to other kinds of training in that it is usually done two to three times a week (this depends on the time of the competitive season). Since plyometrics involve precise firing of the nervous system, it is highly recommended that they be done in a non-fatigued state – in other words, not after strength or endurance training.

Beginners should do no more than about 10 repetitions per set, and generally no more than 80 to 100 foot-contacts per session.

Another commonly overlooked or misconstrued concept is the rest period between sets. As a general rule the rest period between sets should be five to 10 times longer than the exercise set. So, if it takes five seconds to complete the exercise, you should rest for 25 to 50 seconds before doing the next set.

This often feels like a very long time when you are doing plyometrics, but it’s crucial in order to maintain proper form and avoid injury. This is another good reason to avoid doing these as part of a conditioning circuit.

Guidelines set out by the NSCA recommend that prepubescent children can do hopping exercises, but should not do drop-jumps, since the growth plates of their bones have not yet fully developed.

Adolescent and adult athletes should not attempt drop-jumps until they can squat 1.5 to two times their body weight. Elite athletes are often this strong, but recreational athletes or boot camp and aerobic participants are seldom strong enough and should avoid any kind of drop-jumps.

 

Kerry Senchyna holds a degree in kinesiology and is owner of West Coast Kinesiology.