What is oxygen debt?

Oxygen debt refers specifically to the body's need to restore oxygen levels that were depleted during strenuous exercise. During intense physical activity, muscles work anaerobically when demand for oxygen exceeds supply, resulting in a temporary state of oxygen debt. This occurs because the body initially taps into its stored energy sources without the availability of enough oxygen, leading to a deficit when physical exertion subsides.

After exercise, the body enters a recovery phase where it must replenish the oxygen stores in muscles and blood, convert accumulated lactic acid back into glucose (through a process known as the Cori cycle), and restore other metabolic processes that were disrupted during high-intensity activity. Thus, the need to replace depleted oxygen reserves is central to the concept of oxygen debt and its physiological implications in recovery and muscle function.