Clinical Workload Decreases the Level of Aerobic Fitness in Housestaff Physicians

PURPOSE: To examine the relationship between clinical workload and aerobic fitness. METHODS: Twenty healthy intern and resident volunteers were studied in a cross over manner to compare their aerobic fitness after a 1 month "easy" clinical rotation (ECR) to that after a 1 month "hard" clinical rotation (HCR). The ECR and HCR were prospectively estimated as requiring <60 (ECR) and >70 (HCR) total hours per week of hospital work respectively. Aerobic fitness was determined by directly measuring peak oxygen uptake (peakVO2) during peak cycle exercise testing after each rotation. Clinical workload for the month preceding the exercise test was estimated by documenting the amount of hospital work and sleep lost because of on-call duties. The average weekly amount of effective aerobic training for each rotation was also documented. RESULTS: Trainees had a 206.4 (P = 0.0019, 95% CI 94-318.8) mL/min or 3 mL/kg/min (P = 0.0019, 95% CI 1.5-4.4) improvement of peakVO2 after the ECR compared with the HCR. Trainees averaged 1 (95% CI 0.16-1.81) less hour per week of exercise training, 34.1 more hours per week of hospital work (95% CI 23.0-45.3, P < 0.0001) and lost 19.1 hours more sleep per month (95% CI 11.8-26.4, p < 0.0001) during the HCR compared with the ECR. There was no correlation between changes in peakVO2 and changes in exercise training between the two rotations. CONCLUSION: Clinical workload seems to adversely affect aerobic fitness independent of changes in exercise training. This supports previous less-objective survey data.