Benefits of leggings sandbags: See how to practice leggings with sandbags. What you need to practice sprinting with your legs is to improve the explosive force of your legs and the contractility of your muscles. It is necessary to tie sandbags to practice kicking, which improves the explosive force and speed of kicking. To put it bluntly, it is a dual exercise of strength and speed. If you practice long-distance running, you should mainly practice the anti-fatigue and endurance of your legs. Long-term practice can improve your cardiopulmonary function.