Running on a treadmill: what is it like?
Training on a conveyor belt that moves under your feet may unsettle some runners. Unlike running outside, adapting your stride is vital. The absence of horizontal movement requires athletes to put their feet down more quickly on the deck. As a result, the propulsion phase is decreased. This unnatural movement can modify how your muscles work: on a treadmill, your hamstrings aren't used very much. On the other hand, your hip flexors (iliopsoas) compensate for this action by working harder.