why do we swing our arms when we walk

We swing our arms when we walk because it helps with balance, stability, and energy efficiency. Arm swinging counteracts the rotational forces and momentum caused by our legs, which reduces the overall energy needed to walk and makes walking smoother. Studies have shown that people who swing their arms naturally use about 12% less metabolic energy than those who keep their arms still. The movement of the arms is mostly passive, driven by the body's motion like a pendulum, requiring minimal muscle effort, but significantly aiding in reducing the load on the legs and helping stabilize the body’s rotational motion during walking.