Originally Posted by Dave Van Skike
With running, maybe we're talking about the same thing. your form needs to be good enough to relax every part of your body that is not directly assisting the movement- quiet upper body, minimimal tension to maintain a solid core, "springy" legs, loose ankles etc.
I couldn't agree more with this and I think it is what makes tempo running so effective, learning to stay relaxed while you are exerting yourself. The relaxing part can quite easily go out the window when you are pushing things at 100%.