From the article, note these sentences:
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.”
This is great information for all those runners out there who struggle with upper hamstring issues.
This is the root-cause of it. The picture of the running gait being more circular makes perfect sense.
The closer the foot is to the butt when you swing your leg thru allows your leg to pull through faster. Faster pull means higher turnover.
I teach my runners a hand postition I learned in speed skating which is exactly what Salazar uses. It is proven to be the best hand position.
I also instruct the runners to use a hand height that mimics them adjusting the waistband of their running shorts. Higher than that and you are wasting energy. Think back to basic aerobics classes, the higher the arms the harder the heart has to pump.
Good stuff!!!