Cardiovascular and ventilatory responses to exercise breathing 100 per cent oxygen.

Abstract

Five young male subjects worked at loads corresponding to 25, 50, and 67 per cent of their maximum oxygen uptake while breathing either room air or 100 per cent oxygen. Cardiac output, blood pressure, heart rate, oxygen uptake, and ventilation were measured during these steady state conditions. Ventilatory volumes decreased progressively at increasing work loads while breathing oxygen. Heart rate was lower, while cardiac output and stroke volume tended to be higher at each work load while breathing oxygen when compared with values obtained with air breathing at the same work level. Diastolic and mean blood pressures were also higher when working under hyperoxia although the differences became less as the level of work increased.