Take a close look at the following images. In the first image, you'll see the same two athletes I posted previously. Using the program's ability to overlay images, I can highlight the two individuals at the point of toe-off. How much difference do you really see?

Now, the next two images show the air time from toe-off to touchdown. The air time is identical. However, look at the difference in step length. From the Weyand 2000 study: "The time spent in the air (mean aerial time) at top speed did no vary as a function of the top speeds for our 33 subjects during level running. This was due to the equivalence of the vertical impulses determining aerial times among fast and slow runners. However, fast and slow runners achieved these equivalent impulses with different combinations of effective force and foot-ground contact times. Faster runners applied greater forces during briefer contact periods, whereas slower runners applied less ground forces during longer contact periods."