Physiological sex differences in response to exercise

Abstract

Physiological sex differences influence how males and females respond to exercise due to variations in hormonal profiles, muscle mass distribution, cardiovascular capacity, and training load tolerance. Males typically have 10–15% greater hemoglobin concentrations and higher maximal oxygen uptake of (VO₂max) relative to body weight, enhancing aerobic performance, while females generally possess higher body fat percentage, lower absolute muscle mass, and greater reliance on lipid metabolism during submaximal exercise. Estrogen supports membrane stability, antioxidant defense, and fat oxidation, whereas testosterone drives hypertrophy, strength gains, and red blood cell production. Hormonal fluctuations across the menstrual cycle alter performance, with the follicular phase favoring endurance and the luteal phase potentially increasing fatigue. Females often experience greater GI discomfort but lower sweat rates than males, who lose more body fluid and require more aggressive hydration strategies. Males show greater creatine kinase and myoglobin responses, reflecting more structural muscle damage and delayed on set of muscle soreness severity, while females benefit from faster recovery via estrogen-mediated protection. Training load thresholds also differ: males tolerate higher absolute external loads but risk overtraining without sufficient recovery; females may face higher relative internal loads and greater susceptibility to endocrine disruption such as relative energy deficiency in sport. Tailoring exercise programming to these sex-specific cardiovascular, metabolic, hormonal, thermoregulatory, inflammatory, and recovery profiles can optimize performance, minimize injury risk, and improve long-term adaptation.