> Extrapolating from your last sentence – fatigue? Yes. They train to exert the maximum amount of effort in order to optimise their time. If they're at maximu

> Extrapolating from your last sentence – fatigue? Yes. They train to exert the maximum amount of effort in order to optimise their time. If they're at maximum speed at the finish line it does them no good, they likely could have expended more energy to be quicker in the middle of the run to cut their time.