Substrate metabolism during exercise: Sexual dimorphism and women's specificities

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Nutrition

Background:

• Sexual dimorphism exists in energy metabolism, with sex steroids influencing body composition and substrate storage.
• Women typically rely more on fat oxidation and less on carbohydrate oxidation compared to men during exercise at similar relative intensities.
• 17-β estradiol is identified as a key hormone regulating body composition and substrate metabolism in women.

Purpose of the Study:

• To review sexual dimorphism in energy metabolism.
• To describe the impact of women's hormonal status on substrate oxidation during exercise.
• To highlight the importance of considering hormonal status for optimizing female health and performance.

Main Methods:

• Review of existing scientific literature and data.
• Analysis of studies using stable isotopic tracers to measure whole-body substrate oxidation.
• Examination of the effects of hormonal fluctuations (menstrual cycle, oral contraceptives, pregnancy, menopause) on metabolism during exercise.

Main Results:

• No significant differences in whole-body substrate oxidation rates were found between follicular and luteal phases of the menstrual cycle during endurance exercise.
• Exercise intensity is a crucial regulator of substrate oxidation, potentially explaining discrepancies in menstrual cycle studies.
• Synthetic ovarian hormones in oral contraceptives may influence substrate metabolism, but further research is needed to confirm effects on lipolytic activity and substrate utilization.

Conclusions:

• Hormonal status significantly affects substrate oxidation during exercise in women.
• Factors such as the menstrual cycle, oral contraceptive use, pregnancy, and menopause alter body composition and substrate utilization.
• Understanding these hormonal influences is essential for tailoring exercise regimens and optimizing health and performance in women.