The Effects of Breathing 100 Percent Oxygen during Rest, Heavy Work, and Recovery

The effects of breathing 100% oxygen on resting, exercise, and recovery oxygen consumptions, pulmonary ventilation volumes, and heart rates were observed on six highly conditioned male athletes. The subjects rode a bicycle ergometer at a heavy work load for five minutes, breathing either normal air or medical oxygen. Ventilation volumes were determined by the open-circuit Douglas bag method, measuring inspired and expired volumes. Gas samples were analyzed for nitrogen and oxygen concentrations on Van Slyke and Beckman gas analyzers, and heart rates were recorded via a telemetry-electrocardiograph system. The results indicated a substantial increase in resting oxygen consumption, a decrease in resting ventilation volume, a marked decline in exercise and recovery ventilation volumes, and an insignificant lowering of the energy cost of exercise during the oxygen experiments. No appreciable differences were noted in heart rates between the oxygen and air experiments.