Exercise after sleep deprivation.

The influence of acute sleep loss on subsequent exercise remains poorly defined. To investigate this question, six subjects performed cycle ergometer exercise daily in a 3-d series that included 30 h without sleep before day 2, and then unlimited sleep before day 3. Each day 8 min of exercise was performed at each of three constant external work loads that required approximately 25%, 50%, and 75% of the VO2max. On days 2 and 3 after sleep loss, exercise at all work loads resulted in unchanged O2 uptake (VO2), CO2 production (VO2), CO2 production (VCO2), ventilation (VE), heart rate, and arterial blood perssure, when compared with the equivalent day in a control series. Despite these unchanged physiological variables, ratings of preceived exertion were increased significantly during moderate and heavy exercise on day 2 (P less than 0.05), but returned to control levels on day 3. In further experiments on six additional subjects, sleep loss failed to alter VO2max, while it significantly reduced peak exercise heart rate (P less than 0.05). These results suggest that acute sleep deprivation primarily alters the psychological responses to moderate and heavy exercise.