Humans naturally move their arms while running, it is a natural act! You have to make a conscious effort to walk without using your arms and an even bigger effort if you running. This leads us to believe there must be some kind of benefit by using this technique, otherwise, evolution should have left it out of our nature, since it is an energy consuming movement.
We move our arms contrary to our legs, so when your left foot goes. Your arms work as a counter-balancing force to the angular momentum generated by the legs(1,2). The angular momentum is the amount of rotation of a body and it depends on the velocity as well as the mass of the object. This compensation is important because it keeps the runner in a straight line, and it keeps the visual aim stable.
The left arm is counter-acting the angular momentum caused by the right leg so that the body of the runner is kept straight and the visual aim remains stable. Continue reading “How to Swing your Arms”