McArdle, W. D., Katch, F. I., & Katch, V. L. (2004). Exercise physiology (5th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.

"Plyometric exercise overloads a muscle to provide forcible and rapid stretch (eccentric, or stretch phase) immediately before the concentric or shortening phase of action. Like many sports situations, the rapid lengthening phase in the stretch-shortening cycle produces a more powerful subsequent movement largely because of two main factors: . . .

Implication. A baseball pitch involves a plyometric action. When the arm is cocked through very rapid pre-stretch, the muscles' and connective tissues' natural elastic recoil functions are activated, not metabolic muscle shortening.

Return to Table of Contents for this issue.