Ground Reaction Force

Acceleration sprints are a great form of improving your overall athleticism. The ability to effectively accelerate with mechanical efficiency is an important quality to possess in a variety of sports and/or recreational activities. Although acceleration involves the use of many muscle groups working together, your hip extensors play a significant role in sprint acceleration performance. The more force your foot exerts against the ground, the faster your body moves (Newton’s Third Law).

Braking Force in Top Speed

After the first few meters of acceleration, your torso moves from a forward lean to a vertical position as you reach your top speed. Once at top speed, your goal is to minimize contact with the ground by getting your feet down quickly and driving the ground away. Slower sprinters often land their feet too far ahead from their hip (~12 inches), whereas faster sprinters land with their feet closer (~6 inches). For maximum speed, it is best to have your feet on the ground as little as possible (⬇️ braking force) while applying maximum amount of force during extension (⬆️ propulsive force).