Coach's Analysis

Vertical Jumping Factors

 Another PowerStarts Secret

The counter movement of squatting down just before jumping is part of the mechanics of vertical jumping.  The counter movement involves muscles acting to slow the body and initiate the reverse of the desirable movement.  As these muscles are activated, force is increased in the tendon-muscle complex, increasing its stiffness or resistance to stretching.  The result is a storage of elastic energy in the muscles and tendons referred to as "muscular preload" or "coil".  The elastic energy builds up and then is released with the "desirable movement."

This counter movement (squatting) and desirable explosive movement (jumping) typically requires force to be developed in a time period between .20 and .35 seconds (200-350 milliseconds).  A suddenly-imposed stretch also increases neural stimulation to the muscles.

Without the sudden counter movement of squatting the resultant explosive movement is not as productive as those which employ a sudden stretch-reflex performance.

CAUTION:  Heavy-strength training in some cases might even reduce the ability of the muscles to develop force rapidly.  Training with heavy loads improves maximal isometric strength but not the maximal rate of force development that is paramount for vertical jumping enhancement.  Light load training, on the other hand, with a emphasis on speed of movement increases an athlete's ability to develop force rapidly.

Heavy strength training is of little benefit to already strong individuals who wish to perform explosive movements preceded by counter movements that are initiated from a static crouch position such as track starts, football lineman stance and starts from starting platforms for swimming.

Methods that emphasize rapid force development, high contraction velocities and use of the stretch-shorten cycle movements should be part of the training preparation for vertical jumping with emphasis on explosive power rather than strength.

Animated Photo 9

Notice the squatting down motion.  This counter movement is what causes the muscles involved to be stretched rapidly, like a rubber band.  Then the rubber band springs back, or shortens to accelerate the body by launching the body up.