Why do runners try to minimize ground contact time?

Answer Details

Running speed is determined by two factors: stride length (the distance covered per step) and stride frequency (the number of steps per unit of time). Ground contact time directly affects stride frequency: the less time the foot spends on the ground, the more steps a runner can take in a given period.

When the foot is on the ground, it is in the support phase. Once it leaves the ground, the runner enters the flight phase, during which they travel forward through the air. By minimising ground contact time, runners spend proportionally more time in the flight phase, which increases stride frequency and overall speed.

Additionally, short ground contact time is associated with a stiffer, more elastic leg action that allows the muscles and tendons to store and return energy more efficiently, much like a bouncing spring. This reduces energy wasted during each ground contact.

The other options are incorrect. Minimising ground contact time does not aim to increase jump height, nor does it allow for rest on each step. While energy efficiency does improve, the primary and direct goal is to increase running speed.