Just a small question regarding hip rotation. During full flight should the hips rotate in a sort of swivel motion as the driving leg comes through? or should they remain flat, sort of in alignment as they are when standing when standing? Have just seen Ben walk away from everyone during a repeat of a world champ 100m final during the late 80’s. From what I saw Ben’s hips were rotating significantly more than the rest of the field. I can see how this could create a marginal increase in stride length, but would this have an effect on stride frequency?
I believe Charlie has stated that if you look at all of the top sprinters it is apparent that there is some hip rotation which adds to stride length, it occurs naturally and athletes should not be taught to “lock out” there hips as some have suggested. And your right about the rotation in BJ’s 9.79 run, it’s very evident.