Vertical Jumping Factors

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".  (See The "Leaning Tree" Syndrome). 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 200 and 350 ms. (ms=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.

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