I have purchased and read Danny Dreyer's book and DVD and have a new appreciation for the importance of posture, leaning and landing mid foot and loose lower legs. I am in the beginning stages of learning the correct way of running and am making progress. However, I am experiencing tightness in my calves like I have never felt before. Having said this, can someone help me answer this question? If gravity and lean were the major providers of speed, why wouldn't I be as fast as the fastest Chirunners if I had equal form, used the same lean, turn over and stride length? My intuition tells me that even the best Chirunners subconsciously use their lower legs for pushing off, otherwise, from a physics standpoint, we should all be equal. Thanks!