Chicago bystander wrote:
And ritz's form looks even worse than usual next to the perfectly upright japanese guys.
Unless they have a tailwind that's ~20km/hr (I know there *was* a tailwind at various stages), if the Japanese guys are "perfectly upright" then their form is NOT a model.
Here's why. Assuming you're moving at an even speed, with no tailwind, you will be (in effect) be facing a headwind. As a matter of physics, your body *as a whole* will be leaning forward to offset the effect of that "headwind"; the only question is how your body parts are distributed.
If (in the no-tailwind situation) your torso is bolt upright, then your body is "bending" somewhere. In most cases, it will be at the hips: the legs will be "tilted" extra-forward to create the overall forward lean that the torso is not contributing to--and that *must* take place as a matter of physics.
Typically, this means that the pelvis will be tipped forward, rather than level. A level pelvis makes it fairly easy to raise the knees; a tipped-forward pelvis makes that harder, and also encourages having the footfall be more in front of the center of gravity. That introduces an extra braking force in each step, and also causes the legs more to pull (which they don't do well) than to push (which they're designed for) in accomplishing each step.
Look at most of the top EAfrican marathoners--again, assuming they don't have a tailwind that approximates the speed they're going--and notice that they maintain a good strong body alignment (no "break" at the hips), and that their whole bodies exhibit the slight forward lean that has to be there.