The Biology of Sex and Sport

» Sex and gender are not the same. Sex is defined by the human genotype and pertains to biologic differences between males and females. Gender is a fluid concept molded by self-perception, social constructs, and culturally laden attitudes and expectations of men and women. » In general, males have longer limb levers, stronger bones, greater muscle mass and strength, and greater aerobic capacity. Females exhibit less muscle fatigability and faster recovery during endurance exercise. » Physiologic sex-based differences have led to an average performance gap of 10% that has remained stable since the 1980s. The performance disparity is lowest for swimming and highest for track and field events. » The International Olympic Committee currently mandates that female athletes with differences of sex development, or intersex traits, and transgender female athletes must limit their blood testosterone to <10 nmol/L for 12 months to be eligible for competition in the female classification.