The Skinny on Plyometrics By: Zach Reed “Jimmy can jump.” I don’t know if you have ever watched Seinfeld, but there was this episode with a character named Jimmy and he always referred to himself in the third person by saying Jimmy this or Jimmy that. Basically, he wore the jump shoes that elevate the front of your foot thereby elongating the Achilles’ tendon and strengthening the Gastrocnemius and Soleus. The episode culminated with Jimmy getting hurt and George having to try and be a salesman for them at a Foot Locker knock off. When George has to demonstrate the results of the shoe he does an extension jump barely high enough to slide a sheet of paper under his feet. Now, I’m not trying to discredit the shoes, but let’s look at some of the basic science behind plyometrics (plyo’s). Without turning this article into a derivative of a textbook that can explain it far better than me, consider a few basic principles in regards to plyometrics. Plyometrics are a rapid eccentric contraction followed by a rapid concentric contraction or a rapid loading and a rapid release. In order for plyo’s to be successfully trained there must be a rapid stretch and release. This is referred to as the stretch-shortening cycle. Since the eccentric and concentric phases are the beginning and the end respectively, the amortization phase is the middle portion. The amortization phase is the switch between the eccentric and concentric phases. It is highly important that the amortization phase is as little as possible. The longer the transition phase takes, the lower the power production will be. The transition between the load and release is an integral part of plyometrics and not to be overlooked. Nevertheless, a rapid load and release are still the defining points of plyo’s that we all notice the most. Try this little test on yourself. Put your hand on your thigh and pick up your index finger without any help. Then, slam your index finger to your thigh. Did you feel it? Now, pick up your index finger with the opposite index finger. Pull it back as quick as you can and release it. Of the two, which did you feel more? The second hit was much more powerful because a rapid load and release was involved. When training for plyometrics begin with the end. Teach athletes how to land with knees (or elbows) slightly bent. Also, land on the whole foot in order to absorb the shock of the jump with your foot’s arches. More importantly, it will prepare the body for another jump. If the foot lands too plantar flexed, then part of the loading is decreased, thereby reducing the release by decreasing the loading capabilities. Consequently, the power output will also be diminished. Depending on the exercise, you might teach how to land in an “athletic stance.” The stance cues are knees bents, chest big, back tight and eyes on your target. This stance is very similar to a quarter squat or a start stance for a clean. Next, emphasize intensity or effort. Each jump should be at maximum effort and all-out. However, make sure you delineate the outcome, whether it is height, distance or speed. For example, tuck jumps should be done in rapid succession with no movement linearly; while a long jump moves in a linear path; and a single leg hop with a cycle incorporates a tuck jump and linear movement. Another example is a box jump. There’s a big difference between jumping a box, jumping down and jumping back up to the same box as opposed to jumping from box to box to box. Anyway, the point is the desired outcome of the jump while still maintaining intensity and effort just like a clean. When we do cleans we never do more than six reps. Let’s say we are doing four reps of cleans. Each rep should involve rep replication. In other words, each rep should be a clear succinct rep with little to no carryover or involvement from the previous rep. Because detriment of form is high, limit the number of jumps. Remember, the outcome is to increase power. By definition, power cannot be maintained over periods of time without adequate rest. Use at least a 1:5 work to rest ratio; if not more. Another point that often gets overlooked is that it is recommended that an athlete can squat 1.5 times his or her bodyweight before beginning a plyo program. Be aware that some kids are not aptly prepared for plyo’s and there is an inherent danger in doing them. Careful monitoring of volume and type of plyo is important. For example, when we do single leg hops for fifteen yards we allow athletes to do them with both feet like a long jump. However, if the single leg hop is mastered, then add a cycle to each jump (butt kick). An adequate strength base is very important to the athlete’s safety and to the ability to carry- out a proper training program. In our program sometimes we do plyo’s as a warm-up on lifting days or on days between lifting days. We’ve done it all different ways; even in the sand pit. You can take the most simple plyo; put a kid in sand and the intensity skyrockets. The easy jump becomes much more difficult. So, we do it all different ways. Just remember, more is not always better and coach effort. For further reading and examples of upper and lower body plyometrics there is a wealth of resources readily available. I recommend Donald Chu’s Jumping into Plyometrics, James Radcliffe and Robert Farentinos’ High Powered Plyometrics. For dvd’s Vern Gambetta does a great plyo series. A quick website is exrx.net and it has real-time videos. In conclusion, adding plyo’s to your program is a must. Every athlete can benefit from the inclusion of plyo’s from males to especially females. The rate of ACL tears could be reduced with proper plyo training in order to balance the already quad dominate leg musculature of the body and to prepare the body for the shock absorption from landing or in contact sports. The eccentric load on the hamstrings will help strengthen the back of the thigh (even though the quads will always be stronger). All sports, in some way or another, can benefit from plyo’s and can be incorporated easily into a warm-up or become a dominate part of your training program. Zach Reed, CSCS, is the Strength and Conditioning Coordinator at Kennesaw Mountain High School in north metro Atlanta.
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