The effect of single-bout eccentric exercise on contractile properties in mouse soleus and tibialis anterior muscles.

Recurrent eccentric exercise (EE) has been shown to increase skeletal muscle performance, specifically force production, and decrease susceptibility to subsequent re-injury via protective mechanisms, known as the repeated bout effect (RBE) [1,2]. Eccentric contraction during EE actively stretch muscle and may induce injury if sarcomeres are disrupted or ruptured. Prior studies suggest that EE triggers a cascade of reparative and fortifying mechanisms which remain poorly studied experimentally [3]. We sought to isolate the initial bout of exercise in RBE to determine if contractile and elastic properties in muscles with distinct fiber types are enhanced exclusively through training (RBE) or if episodic exercise eliciting a single bout effect (SBE) can be beneficial.