Another short example of Powell (55-65):
this short-man style combined with his long levers and relaxation is mind blowing. How does one run with a heel recovery such as that for a whole 100m let alone 200m. I'm thinking it has something to do with his arm swing.
it looks as though powell begins to pull his right upper arm and elbow back and up away from being in-line with his torso(side view) just as the left upper arm and elbow are in mid-elastic response(closing back from 95degree) on the way back down to being in-line with the torso. The lower arms and hands are just relaxed and flowing freely and it looks as though he just keeping them relaxed and concentrating on pulling the upper arms and elbows back and away from in-line with the torso as the other upper arm is already returning down.