Changes in cardiorespiratory responses during exercise with acute exposure to low, normal or high oxygen concentrations at normal air pressure: In search of an effective exercise environment for physical therapy

Abstract

Purpose: We investigated the effects on cardiorespiratory responses during exercise with acute exposure to low to high oxygen environments under normal air pressure. Subjects: The subjects were 7 healthy adult males. Method: Using the membrane separation method, we established 3 oxygen concentration conditions, low, normal and high, at normal air pressure. Subjects performed a ramped load exercise on a bicycle ergometer under each condition, and we measured the cardiorespiratory response from at rest to the end of exercise. We made a comparative study of cardiorespiratory reactions between the low and normal, and normal and high oxygen concentrations. Results: Compared to the normal oxygen concentration, at the low concentration, the load on the cardiorespiratory organs significantly increased. In particular, at loads above the anaerobic threshold the load on the respiratory organs had an increasing trend. Large differences were not found between the high and normal oxygen concentration conditions. Conclusion: The results show that acute exposure to a low oxygen environment at normal air pressure has a similar effect on cardiorespiratory load as acclimatization to a low pressure low oxygen environment.