Biceps femoris long head sarcomere and fascicle length adaptations after three weeks of eccentric exercise training

Abstract

Background: Eccentric exercise is widely used to increase muscle fascicle lengths and thus decrease the risk of muscle strain injuries. It is commonly assumed that increased sarcomere number drives this training adaptation and reduces risk of muscle strain, however this has yet to be experimentally tested. This study used a new microendoscopy technique to determine whether addition of sarcomeres can account for increases in fascicle length of the Biceps femoris long head (BFlh) after 3 weeks of eccentric exercise.