The reason why he rested for five minutes was to bring the heart and breathing rate back to normal in order to restore homeostasis. If he did not rest the results would have been affected, this is because cycling with no breaks would have caused him to slow down and in worst case scenario he would have collapsed due to the increase of oxygen and energy demand. This is because the muscle cells respire more during exercise which means oxygen and glucose must be supplied to his muscles and carbon dioxide must be removed speedily. Respiration releases energy to the cells from glucose. This can be aerobic respiration which requires oxygen or anaerobic respiration that does not require oxygen. Aerobic respiration releases energy
