Sex Differences in Marathon Running: Physiology and Participation

ABSTRACT Introduction Males are faster than females in the marathon, largely due to sex differences in physiology, but sociological factors influencing lower participation rates of females than males may also contribute. Purpose This study aimed to determine whether the sex difference in marathon performance is predicted by the proportion of male to female runners and how this prediction changes among lower-placed runners across age groups. Methods The number of male and female finishers within 5-yr age groups (20–79 yr) and times of the first 10 age-group runners in the Chicago (CHI; 1996–2018) and New York City (NYC; 1980–2019) marathons were analyzed. Results The male/female participation ratio declined across years for the CHI (1996–2018: 2.19–1.16, P < 0.001) and NYC (1980–2019: 6.76–1.36, P < 0.001) marathons, but increased with age ( P < 0.001) and place (1st–10th place, P < 0.001). Male runners were faster than female runners across all age groups for the CHI (17.2% ± 6.8%, n = 2328) and NYC (18.8% ± 7.4%, n = 4226) marathons. The sex difference in performance was smallest for 1st-place and largest for 10th-place finishers for both marathons. The ratio of the number of male to female runners was associated with the sex difference in velocity for NYC ( r 2 = 0.32, P < 0.001) and CHI ( r 2 = 0.28, P < 0.001). The strength of the associations increased between 1st and 10th places. Conclusions Fewer female relative to male runners in an age group predicted a larger sex difference in performance in two world-class marathons. Low participation rates of female runners mask an accurate understanding of the sex differences in marathon performance due to physiology, with broader implications for women’s health in biomedical research.