Ready… Set… GO! Imagine you are running a 100 m sprint. World-class athletes can do this in less than 15 seconds. Sprinting like this is an all-out effort, though. A lot of energy is needed to move this fast. Muscles have enough ATP in them to move this fast for a second or two, but to move this fast for longer they need more energy, FAST! Athletes sprinting at this level may not even breathe during the 15 seconds of the race. But you’ll see they are breathing heavily for minutes afterward. Cellular respiration cannot make that much ATP that fast. So where do they get the energy to sprint like this?
