An Integrated Mechanistic Approach to Female Exercise Physiology: Menstrual Cycle Fluctuations, Relative Energy Deficiency in Sport (REDs), Protein Kinetics, and Thermoregulatory Acclimatization

Historically, sports and exercise science research has predominantly relied on male cohorts, leading to the erroneous extrapolation of physiological paradigms to female athletes. However, female physiology is governed by dynamic hormonal fluctuations that elicit distinct metabolic, neuromuscular, thermoregulatory, and systemic adaptations. This comprehensive state-of-the-art review integrates evidence across five critical dimensions of female exercise physiology: (1) rigorous methodological frameworks, emphasizing standardized three-step menstrual phase verification protocols to eliminate confounding research artifacts; (2) phase-dependent neuromuscular and performance outcomes, highlighting neurosteroid-mediated (GABAA) modulation of rating of perceived exertion (RPE) and estrogen-driven ligamentous laxity; (3) the multisystemic cascade of Relative Energy Deficiency in Sport (REDs), detailing endocrine downregulations, bone turnover impairments, and the exercise-induced IL-6–hepcidin axis governing iron dysregulation; (4) female-specific protein kinetics and substrate partitioning, establishing targeted leucine thresholds to counteract mid-luteal catabolic shifts; and (5) thermoregulatory challenges, driven by progesterone-induced upward shifts in baseline core temperature and attenuated heat dissipation. Finally, we translate these mechanistic insights into evidence-based guidelines for nutritional periodization, injury mitigation, and environmental management to advance rigorous, female-centric sports science.