Artificially long legs directly enhance long sprint running performance.

This comment addresses the incomplete presentation and incorrect conclusion offered in the recent manuscript of Beck . ( , 211799 (doi:10.1098/rsos.

Does restricting arm motion compromise short sprint running performance?

Background: Synchronized arm and leg motion are characteristic of human running. Leg motion is an obvious gait requirement, but arm motion is not, and its functional contribution to running performance is not known. Because arm-leg coupling serves to reduce rotation about the body's vertical axis, arm motion may be necessary to achieve the body positions that optimize ground force application and performance.