Effect of hypoxia on psychomotor performance during graded exercise.

We evaluated the combined effects of reduced O2 (12%) and graded ergometer exercise (10, 70, and 140 W) on the performance of a psychomotor task. Six men participated in two test sessions each. Each session began with the baseline data (air) and finished with exposure data (12% or 21%, random, unidentified). The gas mixtures were air (control condition) and 12% O2-balance N2 (12% O2 condition). The psychomotor task score was degraded during the 140 W work rate of the 12% O2 condition (p less than 0.05). Reductions of the SaO2 (p less than 0.05) at each work rate proved that hypoxia existed during exercise in the 12% O2 condition. The arterial blood gases indicated that respiratory alkalosis was mixed with metabolic acidosis during the hypoxic exercise. The results differ from previously reported findings of an arousal effect of exercise on psychomotor performance and the decrement of task performance at work rates less than or equal to 50 W. We conclude that hypoxia degraded the performance of the psychomotor task during graded exercise.