To determine if cardiorespiratory fitness decreases in medical interns during their first year of training.
Incoming medical interns at Caritas St. Elizabeth’s hospital were asked to participate in this prospective cohort study. Informed consent was obtained from all subjects prior to enrollment. Medical history, height and weight were recorded. Spirometry and Maximal Voluntary ventilation were performed on a volume displacement, water-sealed spirometer (SensorMedics, Yorba Linda, CA) according to published guidelines (12). Symptom-limited cardiopulmonary exercise test with an incremental ramp protocol was completed on a cycle ergometer (Vmax 29, SensorMedics), while breathing room air. Breath by breath oxygen uptake and carbon dioxide output, pulse oxymetry, and 12-lead ECG were recorded continuously. Maximal work rate (watts), oxygen uptake (VO2) and anaerobic threshold (AT), were measured according to published guidelines (13). After 6 months of internship, we repeated the cardiopulmonary exercise using the same protocol. Results were compared at both times using paired Student’s t-test.
14 subjects (10 male, 4 female) agreed to participate. Repeated measurements were available in 10 subjects (7 male, 3 female). All subjects terminated the test because of muscular fatigue. Significant reductions were observed in maximal work rate (216± 51 vs. 197±52, p<0.007), and in Anaerobic Threshold (1.34±0.33 vs. 1.09±0.24, p<0.0008). No significant differences were seen in peak heart rate, maximal oxygen uptake (VO2), O2-pulse, VO2/WR and HR/VO2 ratios.
6 months after enrolling in a medical internship, normal subjects had a decrease in maximal work rate and anaerobic threshold.
These findings suggest the development of progressive physical deconditioning in normal subjects during medical training. Although this may result from the demanding schedule that is associated with medical training, adequate planning for regular physical activity may prevent the occurrence of such event.
Eduardo Velez Calderon, None.