I have an athlete who has excessive hip rotation during top speed phase, to the point where his foot is striking so far across the mid line of the body that it is hitting where the other foot would normally be when standing. This as opposed to Ben in Seoul:
http://www.youtube.com/watch?v=-gFXa4AcD5w
Is this restricting the athlete in top speed because it is so excessive and causing his body to wobble back and forth?
Where is the knee of the swing leg when the support leg is on the ground? Is it in front or still behind support knee, when in mid-stance?
Try the two follwing drills:
He could run along, tapping the outside of his feet when as they reach their highest point nderneath the butt. His horizonatal speed will not be fast in this drill.
Figure 8 drill. Standing, leaning over with hands on wall or something to grab; your rotate the leg in a figure 8 pattern. The knee is flexed to roughly 90 degrees thru-out the drill. It is considered a dynamic warm up drill. Knee comes forward and up and rotates slightly to side and goes back down again and foot goes behind you, and then flares out to the side and then comes forwards and towards middle then up and out to side and keep repeating. It is a rythmic action.
The above two drills might not solve the problem, but wll educate the athlete further to leg rotation at the hip. If it does not gradually improve, it might be more to do with anatomical structure or muscle activation issues, and I don’t think I’d be able to solve it (if it needs solving) just from a post on the internet. Not sure if my above advice helps, but it’s a starting point to experiment with.
I have to remind myself with something Charlie said years ago about athletes techniqe… It was along the lines of “…even world class athletes have their idiosyncracies (unclasical bio-mechanics) … and you temper with them at your peril.”