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Q3. Why Do We Have Separate-Sex Sport?

A3. We have separate-sex sport and eligibility criteria based on biological sex because this is the only way we can assure that female athletes have the same opportunities as male athletes not only to participate but also to win in competitive sport. We also separate males and females in contact sports for reasons related to on-the-field playing-safety.

From the onset of male puberty, male bodies develop such that they are as a group faster, stronger, and more powerful than female bodies as a group. The performance gap between male and female athletes that emerges from that point typically ranges from 8-20%, but up to 50% depending on the sport and event.

Even pre-puberty, males have substantial testosterone-based advantages, which begin before birth. In utero, male fetuses receive an infusion of testosterone that is later associated with young boys’ somewhat greater strength1 and somewhat greater propensity for aggression – the androgenic effects of testosterone.2 For example, fitness data from over 85,000 children in Australia showed that, compared to nine-year-old females, nine-year-old males were 9.8 percent faster in sprints (running) and 16.6 percent faster in the mile run. They could jump 9.5 percent farther, could complete 33.3 percent more pushups in 30 seconds, and had a 13.8 percent stronger grip.3

Significant male advantage was also found in a study of Greek children pre-puberty. Compared with six-year-old females, six-year-old males completed 16.6 percent more shuttle runs in a given time and could jump almost ten percent farther from a standing position.4 Another Danish study showed six- and seven-year-old males had a higher aerobic capacity (VO2max) than girls in the same age group.5

A 2022 analysis of American swimming records showed that boys’ records in the ten- and-unders (nine and ten-year-olds) average 0.57 seconds faster per 100 yards than girls’ records. Boys’ records jump to an average of 3.01 seconds faster per 100 yards for the 12-and-under group and more than 4.5 seconds faster per 100 yards between the ages of 13 and 18. Jerry Giordano, an attorney who conducted the analysis, concluded that “about two-thirds of the eventual male-female differential in the performance of top swimmers emerges by the age of 12.”The pattern is even more dramatic in children competing in track. Every USA Track & Field age-group national championship record is better than the girls’ record. This is true beginning with the youngest competitive age group (eight-and-under), with the gap growing dramatically during and after puberty.

If we did not separate males and female athletes on the basis of biological sex – if we used any other physical criteria – we would never see females in finals and on podiums.

1 “Boys demonstrate, on the average, greater strength than girls at all ages. Sex differences throughout childhood are consistent, although small.” – Human Growth, Frank Falkner et al., 1978, Page 286.

2 Hooven, Carole, T: The Story of Testosterone, the Hormone That Dominates and Divides Us. New York: Henry Holt, 2021.

Mark J Catley and Grant R Tomkinson, “Normative health-related fitness values for children: analysis of 85,347 test results on 9–17-year-old Australians since 1985,” British Journal of Sports Medicine, Vol. 47, Issue 2 (January 2013)

Tambalis KD, Panagiotakos DB, Psarra G, et al. Physical fitness normative values for 6–18-year-old Greek boys and girls, using the empirical distribution and the lambda, mu, and sigma statistical method. Eur J Sport Sci. 2016;16(6):736–46, cited in Hilton EN, Lundberg TR. Transgender Women in The Female Category of Sport: Perspectives on testosterone suppression and performance advantage. Sports Medicine. 2021;51: (PMID 33289906 and doi: 10.1007/s40279-020-01389-3).

Eiberg S, Hasselstrom H, Grønfeldt V, et al. Maximum oxygen uptake and objectively measured physical activity in Danish children 6–7 years of age: the Copenhagen school child intervention study. Br J Sports Med. 2005;39(10):725–30, cited in Hilton EN, Lundberg TR. Transgender Women in The Female Category of Sport: Perspectives on testosterone suppression and performance advantage. Sports Medicine. 2021;51: (PMID 33289906 and doi: 10.1007/s40279-020-01389-3).

Jerry Giordano, “The Boy-Girl Difference in Swimming Records,” Ricochet, June 25, 2022.