Why do runners swing their arms?
Show answer & explanation
Answer: Arm motion counterbalances the rotation produced by leg motion
Arm motion counterbalances the rotation produced by leg motion ✓ — Arm swing helps counterbalance the rotational effects of leg motion, limiting torso rotation. Experiments find that restricting arm swing can raise running’s energy cost, but the increase depends on how the arms are held.
Arm motion pumps extra oxygen directly into leg muscles — Arm swing does not pump oxygen directly into the legs. Oxygen arrives through breathing and blood circulation, while the arms help manage whole-body rotation.
Arm motion removes the need to use the torso muscles — Arm swing does not switch off the torso muscles. It reduces the rotational balancing work needed, while the trunk still helps stabilize the body during each stride.