NASM PES Certification Practice Exam 2025 – Complete Preparation Guide

The transition from an eccentric contraction to a rapid concentric contraction is best characterized by the stretch-shortening cycle. This physiological mechanism involves an initial lengthening (eccentric phase) of the muscle, followed by an immediate shortening (concentric phase) that occurs rapidly.

During the eccentric phase, the muscle is stretched and stores elastic energy, which is then utilized during the subsequent concentric contraction. This stored elastic energy enhances performance, allowing for a more powerful contraction than could be achieved through a concentric contraction alone. The stretch-shortening cycle is a key aspect of athletic performance, contributing to explosive movements such as jumping and sprinting.

The other options, while relevant in different contexts, do not accurately describe this specific transition. An isometric contraction refers to muscle activation without movement, which does not occur when transitioning directly from eccentric to concentric. A concentric-only movement would imply that there is no eccentric phase involved, which contradicts the nature of the transition being described. The drop jump response is a specific performance test that may utilize the stretch-shortening cycle but does not encapsulate the entire concept of the transition between eccentric and concentric contractions.