In this vintage article relating to how animals who run on four legs utilize their four limbs to “pump” air in and out of their bodies, a picture of efficient motion and function is described: Bramble DM. Axial-Appendicular Dynamics and the Integration of Breathing and Gait in Mammals. Am Zool. 29, 171-86. 1989. The animal’s pendulum like action of the arms and legs act on the core to stimulate the respiratory cycle.
In humans “appendicular dynamics” means arm swing and leg swing connected by our “axial” core. If the leg swinging through the air is not counterbalanced by an arm on the opposite side of the body the mechanical system is imbalanced. If that leg is not joined to that freely swinging arm via a balanced core, the system is imbalanced. Check out the gif below to see how the arms and legs relate in efficient human walking:
https://commons.wikimedia.org/wiki/File:Walk-Cycle.gif#/media/File:Walk-Cycle.gif
Humans are incredibly creative at adapting to imbalance, however adaptive compensations are often at the price of pain, breathing disorders and inefficiency/fatigue. We are not so far removed from our 4 legged friends in the importance of our arms to be used for optimum health and balance in walking and running. I am a big fan of anything that helps with freeing up the arms during walking. Consider over the shoulder purses, back packs or just leaving stuff you don’t need at home or in the car. Give it a try and see how much of a boost your arms can add to your movement and breathing.