Effect of long-term oral contraceptive use on determinants of endurance performance.

We examined the effect of long-term oral contraceptive (OC) use on endurance performance in recreationally active women. Eight women using OC (OC group) and 8 women who were nonusers (CON group) performed a test to determine the peak oxygen uptake for cycling (V[Combining Dot Above]O2peak) and to estimate the anaerobic threshold (AT). Subjects also completed a continuous submaximal cycling test across 3 work stages (two 6-minute work stages below AT, and 1 above AT performed to exhaustion). Pulmonary gas exchange, heart rate (HR), blood pressure (BP), blood lactate concentration ([La]), and ratings of perceived exertion were measured throughout, and cycling economy was calculated. Physical characteristics were comparable between the groups (p > 0.05). Peak oxygen uptake (CON group: 2.59 ± 0.50 L·min; OC group: 2.13 ± 0.20 L·min) and oxygen uptake at the AT (CON group: 1.47 ± 0.27 L·min; OC group: 1.18 ± 0.15 L·min) were significantly different (p < 0.05) between the groups. Expired minute ventilation, HR, BP, [La], and cycling economy for all constant-load work stages were not significantly different (p > 0.05) between the groups. Furthermore, time to exhaustion for severe-intensity cycling was similar (p > 0.05) between the CON and OC groups. The results of the present study suggest that long-term OC use negatively affects peak V[Combining Dot Above]O2 and V[Combining Dot Above]O2 at the AT but does not alter endurance exercise performance.