This article is a MUST READ! The Perfect Stride, published in the New Yorker, has me thinking.
The fastest finishers had a higher thigh drive, for one thing; at its apex, their femur bone was almost parallel to the ground, like the front legs of a bounding deer. They also slapped the ground so quickly with their forefoot that the contact seemed almost incidental
Salazar believes that a runner striking even slightly in front of his body will experience a momentary hesitation while the hamstring labors to pull his torso forward over the grounded foot. “It’s like having a square wheel on your car,” Salazar said. “Each time it comes around, there’s a moment where the car will lurch.”