Oral contraceptive phase has no effect on endurance test.

Area of Science:

• Exercise Physiology
• Sports Science
• Endocrinology

Background:

• Oral contraceptives (OCs) are widely used by female athletes, potentially influencing physiological responses during exercise.
• Understanding the impact of hormonal fluctuations within an OC cycle on athletic performance is crucial for training and competition strategies.

Purpose of the Study:

• To investigate the effects of different phases of a monophasic oral contraceptive cycle on endurance performance and physiological responses in female cyclists and triathletes.

Main Methods:

• Thirteen female athletes using monophasic OCs completed a 1-hour cycling endurance test at three time points: during OC consumption (CONS), early withdrawal (WITH1), and late withdrawal (WITH2).
• Measurements included power output, heart rate, ventilation, oxygen consumption, respiratory exchange ratio, perceived exertion, blood lactate, blood glucose, and serum hormone levels (oestradiol, progesterone).

Main Results:

• No significant differences were observed in mean power output, heart rate, oxygen consumption, respiratory exchange ratio, perceived exertion, or blood glucose across the testing phases.
• Serum oestradiol levels were significantly higher during the late withdrawal phase (WITH2) compared to the consumption phase (CONS).
• Ventilation (VE) and the VE/VO(2) ratio were higher during the CONS phase compared to both withdrawal phases, and blood lactate was higher during CONS compared to WITH1.

Conclusions:

• Despite observed variations in ventilation and lactate, monophasic oral contraceptive use does not appear to significantly alter key endurance performance metrics in trained female athletes.
• These findings suggest that female athletes using monophasic OCs can maintain consistent endurance performance throughout their cycle.