Repeated Sprint Variations According to Circadian Rhythm at Different Menstrual Cycle Phases

Area of Science:

• Sports Science
• Exercise Physiology
• Chronobiology

Background:

• Circadian rhythms and menstrual cycle phases can influence athletic performance.
• Understanding these variations is crucial for optimizing training and competition strategies in female athletes.

Purpose of the Study:

• To investigate the effects of menstrual cycle phase and time of day on repeated sprint performance in women team sport athletes.
• To determine if circadian rhythm and hormonal fluctuations impact physiological responses during intense exercise.

Main Methods:

• Twelve eumenorrheic female athletes completed repeated sprint cycling tests in the morning and evening during the follicular and luteal phases.
• Performance metrics (peak power, mean power, decrement) and physiological variables (heart rate, lactate, perceived exertion, temperature, hormones) were measured.

Main Results:

• Oral body temperature was higher in the evening, while cortisol levels varied with menstrual cycle phase and time of day.
• No significant differences in sprint performance or most physiological variables were observed between menstrual cycle phases or times of day.
• Maximum lactate levels were higher in the evening, but this did not affect overall performance.

Conclusions:

• Menstrual cycle phase and time of day do not appear to be critical factors influencing repeated sprint performance in eumenorrheic female athletes.
• Training and testing protocols for repeated sprints in this population do not need to account for these biological variations.