Plyometrics, more than jumping onto a box Part 1

Part I will discuss the basic biomechanics of what goes on during plyometrics.

Reactivity, elasticity, and sometimes referred to as buoyancy, plays a very important role in all sports and running. The ability to change direction, sprint, and jump rely heavily on the body’s ability to produce force, relax, and repeat force production.

Taking a look at common practice through visiting professionals, reading material, and learning from other great coaches, a very common variation in each persons approach to development is how they incorporate plyometrics. I hear a common phrase; “most athletes aren’t strong enough so I don’t do them.” Which I will expand upon more later. Some think it is all about how many inches you can jump onto a box. Opposite of that some think it is all about jumping off the tallest box you can. I will also explain why the common test for explosive power (vertical jump) doesn’t quiet tell the whole story.

What Happens When You Jump?
First and for most lets take a look at the biomechanics that come into play when performing a jump in relationship to the stretch shortening cycle (SSC). Taking a look at Hill’s model, two of the three components make a serious contribution. The contractile element (CE) composed of muscle fibers, and the series elastic component (SEC) mainly being the tendon. When performing a jump, these components are stretched, allowing them to store energy, and this energy is released upon rapid contraction. The tendon has the greatest capacity to store energy with little stretch do to it being a rigid structure. Unlike the muscle, which is supple, can stretch much further without storing the same amounts of energy. This would promote the concept that a greater the ability to stretch the tendon during a SSC, the more energy that can be released. This stretch in the tendon would be optimal if the muscle does not stretch. Basically, the more eccentrically a muscle acts within a SSC the less stretch you get out of the tendon.

In part II we will look at how you can apply this information and the specific exercises that utilize this component of the SSC.

Testing Week: Hang Clean

In preparing for sports and while putting athletes through a program it is important to always be evaluating them for improvements in abilities such as strength, posture, flexibility and so forth. This week marks about six weeks since our last strength evaluation in which we use 3 exercises as our "indicators" for improvement in strength along with a few skill test to determine our progress over a certain period of time.

Test 1 of 3
Hang Clean

Why

1. Ground Based Movement: The ability for an athlete to produce force against the ground will determine the athletes ability to do jump, run, and accelerate. Also, athletes do everything with there feet on the ground, standing up, and getting from A to B as fast as possible.

2. Multi Joint: The primary goal for us while performing an explosive movement is to achieve triple extension. This would be the full extension of the ankle, hips, and knees in the most explosive manner possible. This is important because triple extension happens when running, jumping, and most anytime you try to produce great amounts of force during competition.

3. Athletic Position: It is important to train an athlete in similar positions that he will play. Due to the fact that most all the positions will assume the athletic position through the duration of a game, it would indicate the importance to develop strength/explosiveness from this position. A great article on this topic see : (Don't) Assume the Athletic Position by Coach Kenn.

So far the testing has gone great. We have had an average increase of ~25 pounds with the best being a 50 pound jump from 320 to 370 in just 6 weeks form the last testing. It is important not to just jump into the hang clean with out progressing however. I wrote a while back about our progression in the clean and it has paid off. I used a bottom up approach, teaching the basic concepts of triple extension through jumping exercises, and loaded jump shrugs. They gradually progressed into high pulls and cleans down the road. We emphasized the hip extension portion a lot by programming basic variations of some corrective stretches paired with the explosive lift to coordinate that pattern.

There are many people who may choose to do these from the floor or simply not at all. Why I chose to do them...Results. Our verticals continue to go up, 40's are all going down so I feel like the force developed from the clean has paid off.