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Are you doing plyometrics right? Many athletes don’t get everything they could from their plyo training, because they don’t understand its purpose.
To understand plyometrics, it’s important to understand its origins. Plyometric training was originally developed by Dr. Yuri Verkhoshansky during the 1970s in the former Soviet Union. His work was translated by Dr. Michael Yessis and brought to the United States, where it was first implemented by the U.S. Track & Field team.
In Explosive Plyometrics, Dr.Yessis defines this form of training as "a method that relies on bringing about a forced involuntary stretch that accumulates energy and then returns it in the muscle contraction after the stretch." This definition includes two very important details that are often misunderstood. The first is the accumulation and subsequent return of energy, commonly referred to as the stretch shortening cycle. The second is the forced involuntary stretch.
Stretch Shortening Cycle
The stretch shortening cycle occurs when muscles are stretched. During this period, energy gets briefly stored in the muscle and is then used to rapidly contract the muscle. The action is similar to the stretch and release of a rubber band and can be clearly seen during a jump. When an athlete first lowers into a jump position, his muscles forcibly contract. Then, he uses that stored energy to propel upward. If there’s no initial descent, the athlete can’t jump as high.
The second part of plyometrics, and the component that separates it from other forms of training, is the involuntary stretch. In regular jumping, the body is voluntarily lowered into a crouch. In plyometrics, however, the muscles are forced to lengthen. The most common example of this involuntary stretch is the Depth Jump, in which an athlete steps off a box and immediately jumps. The impact with the ground causes an involuntary lengthening of the muscles, which the athlete uses to propel upward again.
To prepare the body to handle the impact of plyometric training, an athlete must first undergo regular jump training. This involves exercises like skips, bounds, frog jumps and low hurdle jumps (less then 6 inches), which are often misconstrued as plyometric training. When starting jump training, start slow and focus on one jump at a time. Perform one low hurdle jump, stop to collect yourself, then perform another).
Next, perform multiple jumps in succession. This begins to teach your muscles how to rebound from involuntary lengthening while keeping the forces low.
Once you’re proficient at these jumps, begin Depth Jumps on a low box, eventually working up to a box around eight inches high.
A mistake many athletes make when performing Depth Jumps is increasing the box height too quickly. If the force of impact is too high, your body won’t be able to rebound quickly enough. To achieve maximum force, you must take off within .15 seconds of impact. An easy way to tell if the box is too high is to pay attention to your heels. If they touch the ground on impact, there’s too much force and you need to lower the height. Even advanced athletes have trouble with boxes over 16 inches.
Siff, Mel, and Yuri Verkhoshansky. Supertraining. 6th ed. N.p.: Ultimate Athlete Concepts, 2009. Print.
Yessis, Michael. Explosive Plyometrics. Mich. Ultimate Athlete Concepts, 2009. Print.