*cracks knuckles*
Right listen here weeb while i go science on your ass

The most efficient and fast way to run is by moving your arms forward and back in a curved position. This is due to throwing the weight of your shoulders and arms forward with each step, thus pushing you forward.
However, if you simply run with your arms behind you, you actually create a counter balance which will throw you off balance and slow you down, on top of loosing that boost from not swinging your arms.

Now go watch Hazbin Hotel or something better than that weeb shi-