Much energy is demanded within a short period in a sprint as opposed to long-distance that mainly demands stamina. During sprints, therefore, the energy demands by the muscles my outpace the supply by energy because oxygen is not reaching fast enough for aerobic cellular respiration. This is why sprinting cannot be sustained for long without accumulation of lactic acid in muscles – due to glycolysis metabolisms being the main source of energy.
IN long substance however, the runner does not sprint the entire marathon but run at sustainable speeds allowing the energy demands by the muscles to be met by the more effective aerobic respiration
