Submaximal Cycle Ergometry as a Predictor of Maximal Aerobic Capacity in Women on Oral Contraceptives

摘要

Predicted maximal aerobic capacity (VO2max), using submaximal exercise tests, is used to evaluate fitness for job performance, especially within the military. Women who use oral contraceptives experience a rhythmic variation of circulating synthetic hormones that can influence submaximal exercising heart rate. The purpose of this study was to examine the validity and reliability of two submaximal heart rate-dependent cycle ergometry exercise tests, one used by the Air Force (AF) and one suggested by the American College of Sports Medicine (ACSM), for women using oral contraceptives. Eighteen healthy and fairly active women, aged 19-22 years, completed a maximal treadmill exercise test with indirect calorimetric determination of VO2max followed two days later by submaximal testing. Each of the three tests were conducted in both the quasi-luteal (Q-L) phase (the second week of the active pill) and the quasi- follicular (Q- F) phase (the last 3 days of placebo administration). VO2max was lower (by 1.1 + 0.63 ml/kg/min) in Q-L than in Q-F (Q-L = 38.2+ 1.1 ml/kg/min, Q-F = 39.3 1 1.1 ml/kg/min, P = 0.055). Comparison of VO2max predicted by the AF test to the true maximal value revealed a slight, statistically non-significant (1.5%) overestimation in the Q-L phase (AF = 38.8 1 1.8 ml/kg/min vs Max = 38.2 1 1.1 ml/kg/min, P = 0.3) and a larger underestimation (5%) in the Q-F phase (AF = 37.41 1.8 ml/kg/min vs Max = 39.3 11.1 ml/kg/min, P = 0.06). Between the two phases, the predicted values of the AF test were significantly different (Q-L = 38.8 1 1.8 ml/kg/min, Q-F = 37.4 1 1.8 ml/kg/min, P = 0.02). The ACSM test underestimated VO2max in the Q-L (3%) phase and significantly.