If you’ve spent any time around sprint coaching in the last decade, you’ve heard the phrase “frontside mechanics.” It’s become gospel. Get the knees up. Minimize backside. Keep everything in front of the body. Coaches repeat it like scripture, and the athletes nod along and exaggerate their knee drive until they look like they’re marching in a parade instead of sprinting. Here’s the problem: the research doesn’t say what most coaches think it says. What the Research Actually Found The landmark study here is Haugen and colleagues, published in 2018 in the International Journal of Sports Physiology and Performance. Twenty-four competitive sprinters, 3D motion capture with 21 cameras at 250 Hz, analyzing both acceleration and max velocity phases. This isn’t a small convenience sample filmed on an iPhone. It’s rigorous. The findings surprised a lot of people. Several frontside and backside variables — thigh angle at lift-off, knee angle at