The amount of muscle in the hip join is also important to speed because the smaller the muscle, the smaller the swing of the hindlimbs. The cheetah happens to have a very small amount of muscle there, so it can swing its hindlimbs at a fast rate. This helps them run very fast. When running, the cheetah mainly uses it's forelimb and it's hindlimb. Cheetahs evenly distrubute their muscle fibers.