Muscle Behavior and Properties During Pushups in Human Arm Flexor Muscles

Abstract

Pushups places considerable physical demand on the upper limb and is one of the primary activities associated with the high prevalence of upper limb overuse injuries and pain after the pushup exercise was performed. As a result, recent effort has focused on determining how various propulsion techniques influence upper extremity demand during the push down and up phase of the exercise. However, an important prerequisite for identifying the relationships between the push up and down techniques and upper extremity demand is to understand how individual muscles contribute to the mechanical energetics of pushups. Therefore, the purpose of this study is to measure the muscle stiffness by measuring wave propagation through the muscle under each level of exertion. The analysis will show that muscles contribute to either push (i.e. deliver mechanical power to the floor) or recovery (i.e. reposition the arm), with the shoulder flexors being the primary contributors to the push and the shoulder extensors being the primary contributors to the recovery. In addition, significant activity from the shoulder muscles was required during the transition between push and recovery, which resulted in increased co-contraction and upper extremity demand. Thus, strengthening the shoulder flexors and promoting pushup techniques that improve transition mechanics have much potential to reduce upper extremity demand and improve rehabilitation outcomes.