Some international sports authorities have agreed to let transgender athletes compete in the female category as long as they haven’t undergone male puberty, but that compromise may not be enough to level the playing field.
A newly published study by Brigham Young University researchers found that boys run faster than girls in the 1,600-meter race from ages 6 to 12, with an average performance differential of 7.7%, augmenting the body of evidence indicating that the innate male edge in athletics begins before puberty.
“Our study adds to recent data showing that sexual dimorphism in physical performance exists in children,” said the paper, “Sex Differences in 1600-m Running Performance and Participation for Children Aged 6-12 yr.”
The study of 3,621 children issued this week in the American College for Sports Medicine’s Exercise, Sports and Movement journal used 2007-14 data from the BYU Triple Crown Elementary School Race, an annual event open to all students, not just elite athletes.
Previous research, including two studies released last year, showed that boys in elite track and field routinely outperformed girls in running and jumping events.
“These data highlight two key points: a sex difference in aerobic performance exists in young children and the difference is remarkably consistent, ranging from about 5.6% to 7.7% across a wide spectrum of aerobic abilities, from average to elite,” said the BYU study.
More boys than girls participated in the annual elementary school run, but the authors concluded that the difference in performance “was not a result of lower female participation and suggests that innate physiological sex differences may be responsible.”
The differences in performance increased as the children grew older. The male advantage jumped from 7.3% in fourth grade to 10.3% in fifth grade and 10.7% in sixth grade. Even so, there was one remarkable exception: a second-grade girl who ran faster than all but four of the sixth-grade boys.
“These observations illustrate that, even though male children are on average faster than female children, there is still overlap, with many females outperforming many males,” said the study by researchers Mandy Christensen and Christine Griffiths.
“However, the exceptional performances of females who beat all the males are often seen as evidence that there are no sex differences in children,” they said in the paper. “Our data refute this assumption.”
Colin Wright, an evolutionary biologist and Manhattan Institute fellow, said on the Substack publication Reality’s Last Stand that the research “offers some of the clearest evidence to date that boys outperform girls in running events well before the onset of puberty.”
The findings come as multiple sports governing bodies seek to find common ground on the transgender-athlete issue by specifying that biological males who identify as female may only compete in women’s elite contests if they have never experienced male puberty.
In its 2022 update, World Aquatics said males may compete in the women’s category “if they can establish to World Aquatics’ comfortable satisfaction that they have not experienced any part of male puberty beyond Tanner Stage 2 or before age 12, whichever is later.”
The International Cricket Council said in 2023 that “any male to female participants who have been through any form of male puberty will not be eligible to participate in the international women’s game regardless of any surgery or gender reassignment treatment.”
World Athletics, which governs international track and field, also banned post-pubescent transgender athletes from the female category in 2023, but has since taken its push for competitive fairness a step further.
The organization said in March that it will introduce cheek swabs for chromosome testing for athletes in the female category, citing “new evidence which clarifies there is already an athletically significant performance gap before the onset of puberty.”
NEW: Activists claim male athletic advantage only begins at puberty, and therefore puberty-blocked males can compete fairly against females. That’s a lie.
Blocking puberty doesn’t block all biology.
A new peer-reviewed study shows boys consistently outrun girls before… pic.twitter.com/i0QiKk71Hi
— Colin Wright (@SwipeWright) June 17, 2025
Such policies are rooted in the view that the male advantage doesn’t emerge until after male puberty, a view backed by other researchers.
For example, a 2022 paper in the Journal of the Endocrine Society said that the “only established driver for the athletic differences between men and women is testosterone,” which increases during male puberty.
“The upshot is that prior to puberty, there are no measurable athletic differences between boys and girls,” said the paper, “Fairness for Transgender People in Sport.” “Epidemiologic observations that report otherwise are confounded by societal bias and by access to athletic opportunity.”
Advocates for transgender athletes have decried the stricter rules. OutFront Minnesota said the puberty limit “amounts to a near total ban on participation for all transgender women athletes from competition in their gender category.”
“This standard makes it clear that unless athletes are fully able to articulate their gender identity at a young age, have full support of their parents/guardians and affirming health care providers, and are able (and want) to access pubertal suppression before any signs of significant development that they simply cannot compete in their gender category,” said the LGBTQ group in a 2022 letter to FINA, which is now World Aquatics.
The number of male-born transgender athletes who begin taking puberty blockers before age 12 may be low, but it’s not zero. That number is also likely to climb as U.S. diagnoses of youth gender dysphoria surge.
For example, Becky Pepper-Jackson, the male-born teen who won an injunction against West Virginia’s Save Women’s Sports Act, began identifying as a girl in third grade and taking puberty blockers at about age 9, according to legal documents.
The high school freshman took third place in the girls’ discus throw last month at the West Virginia state track and field championships.
The puberty-blocker argument worked in the teen’s favor last year with the 4th Circuit Court of Appeals, which noted that the drugs “prevented B.P.J. from progressing through the Tanner 2 stage, and as a result, B.P.J. has never experienced elevated levels of circulating testosterone.”
“Because B.P.J. has never felt the effects of increased levels of circulating testosterone, the fact that those who do benefit from increased strength and speed provides no justification — much less a substantial one — for excluding B.P.J. from the girls’ cross country and track teams,” said the court in its April 2024 ruling.
The Women’s Sports Policy Working Group has long argued that biological males enjoy a prepubescent advantage, citing U.S. data as well as studies out of Australia, Denmark and Greece.
“Every USA Track & Field age-group national championship record is better than the girls’ record,” said the organization on its website. “This is true beginning with the youngest competitive age group (8 and under), with the gap growing dramatically during and after puberty.”
