Final answer:
Oxygen is imperative for the conversion of glucose into ATP within the mitochondria during aerobic respiration, yielding approximately 36 ATPs per glucose molecule. When oxygen levels are insufficient, cells rely on less efficient anaerobic glycolysis, which leads to fatigue. Oxygen also aids in post-exercise recovery by repaying oxygen debt.
Step-by-step explanation:
During a run, as you breathe heavily, the oxygen taken in by your lungs is delivered to your mitochondria, the powerhouses of your cells. In the mitochondria, oxygen plays a crucial role in the process known as aerobic respiration. This process involves breaking down glucose from your breakfast, along with fatty acids, into energy that the body can use in the form of adenosine triphosphate (ATP).
Aerobic respiration begins with glycolysis, which generates a small amount of ATP. However, the presence of oxygen allows for the complete oxidation of glucose into carbon dioxide and water, a much more efficient process resulting in the production of approximately 36 ATP molecules per glucose. Without adequate oxygen, your body relies on anaerobic glycolysis, which produces just 2 ATP molecules and lactic acid, leading to fatigue and less efficient muscle performance.
Oxygen is also vital after exercise, as it helps repay the oxygen debt by aiding in the conversion of lactic acid back to glucose and the restoration of energy reserves. This is why oxygen intake remains elevated even after exercise has ceased, as the body works to restore itself to a resting state.