Eccentric exercise is able to mechanically engage muscle, initiating strain-sensing molecules that promote muscle recovery by inducing beneficial adaptations in neural activity and muscle morphology, 2 critical components of muscle function that are negatively altered after injury. However, due to misinterpreted mathematic modeling and in situ and in vitro stretch protocols, a dogma that exposing muscle to eccentric exercise is associated with injury has been perpetuated in the literature. In response, clinicians have been biased toward using concentric exercise postinjury to improve the recovery of muscle function. Unfortunately, this conventional approach to rehabilitation does not restore muscle function, and reinjury rates remain high. Here, the authors present experimental evidence and theoretical support for the idea that isolated eccentric exercise is ideally suited to combat muscle inhibition and muscle strains and is an attractive alternative to concentric exercise.
Lepley is with the Dept of Kinesiology, University of Connecticut, Storrs, CT. Butterfield is with the Dept of Rehabilitation Sciences, University of Kentucky, Lexington, KY.