1. Balance and stability: Keeping your legs parallel to the ground helps to keep your body balanced and stable. This can reduce the risk of collision or distortion between the swing leg and the ground, and reduce falls or injuries.
2, save energy: swinging your legs parallel to the ground can make the action smoother and more effective, reducing unnecessary energy consumption. This helps to improve the efficiency of walking or running, prolong endurance and reduce fatigue.
3. Increase the speed: keeping the swing leg parallel to the ground will help reduce the resistance and air resistance and improve the propulsion and speed.