Physical exercise and menstrual cycle alterations. What are the mechanisms?

Area of Science:

• Exercise Physiology
• Reproductive Endocrinology
• Sports Medicine

Background:

• Athletes exhibit higher rates of menstrual cycle alterations compared to sedentary individuals.
• Multifactorial causes complicate isolating exercise effects from other predisposing factors.
• Physical training may lead to luteal phase shortening and secondary amenorrhea.

Purpose of the Study:

• To investigate the hypothesis that athletes with training-induced menstrual cycle alterations are overreached.
• To explore the hormonal mechanisms underlying exercise-induced menstrual dysfunction.

Main Methods:

• Analysis of cross-sectional and prospective studies on trained and untrained women.
• Examination of hormonal secretion patterns, including luteinizing hormone (LH).
• Investigation of the roles of corticotrophin-releasing hormone (CRH), beta-endorphins, and catecholestrogens.

Main Results:

• Menstrual cycle alterations in athletes are linked to exceeding a certain exercise intensity or volume threshold.
• Subtle changes in episodic LH secretion patterns are observed in both sedentary women with hypothalamic amenorrhea and athletes post-intense training.
• Increased CRH and beta-endorphin levels, along with elevated catecholamine production leading to catecholestrogens, are implicated.

Conclusions:

• Demanding training can trigger increased secretion of antireproductive hormones.
• These hormonal changes inhibit the normal pulsatile secretion of gonadotrophins, leading to menstrual cycle alterations.
• Overtraining syndrome is a likely cause of menstrual dysfunction in predisposed athletes.