The lactic acid builds up and causes an oxygen debt. The lactic acid building up also causes fatigue. Removing the lactic acid after exercise is the cause of the oxygen debt – the oxygen debt is why you breathe deeply after exercise for some time. You are 'repaying' the oxygen debt.
So after exercise, there are other factors causing an increase in oxygen needs as well as repaying the lack of oxygen during exercise. Over time the oxygen consumption levels out to a steady-state. After exercise, the oxygen is paid back (oxygen debt).
(ii) Activities that can result in oxygen debt: Running; boxing; swimming /any correct example of strenuous activities.
For which exercise would oxygen deficit be the largest? Response Feedback: The higher the intensity of exercise and the less trained the person, the larger the oxygen deficit. In both cases, there is a greater reliance on anaerobic sources before aerobic systems are able to supply ATP.