A new study mapped how power shifts as speed increases. At slower velocities, the plantar flexors drive most of the work, but as speed rises, their role drops while the hip extensors and hamstrings take over.
Once you move past roughly 22 km/h, sprinting becomes a hip dominant
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task. That’s why you need to develop the hips and hamstrings to handle the highest outputs at max velocity.
Speed Kills shows you exactly how to do that, how to target the right muscles at the right speeds, and how to program sprint training that actually transfers to