Question

why we swing our hand while walking or running​

Answer 1

In other words, swinging your arms while you walk helps to reduce the total amount of energy it takes to walk. ... Researchers found that normal arm swinging actually doesn't use much energy from the arm muscles. Simply walking causes the body to sway in a way that makes the arms move naturally, like a pendulum.

Answer 2

Answer:

to attain speed and to reduce friction by air