Professor Gregory Brown Explains Why Men Shouldn’t Compete in Women’s Sports

Female athletes across the country continue to face situations in which they are forced to compete against males, due in large part to athletic association policies that allow this to happen.

At the 2026 California Interscholastic Federation track and field state championships, a male athlete named AB Hernandez won first place in the girls’ high jump and triple jump—forcing the female athletes who actually earned those spots to share the podium with him. Hernandez’s winning high jump mark of 5 feet, 10 inches would not have placed in the boys’ competition at all. Every boy who made the state final cleared at least six inches higher.

In West Virginia, the picture is similarly troubling. B.P.J., a 15-year-old male who identifies as a girl, won the girls’ state championship in shot put as a sophomore—adding to the history of having displaced 470 female athletes over 1,400 times in competition.

While common sense is enough to show the harms caused by these policies, a detailed expert report from Dr. Gregory Brown, a professor of exercise science at the University of Nebraska, sheds more light on the physiology behind why allowing men to compete in women’s sports is unfair to women and girls.

Dr. Brown has authored more than 60 peer-reviewed publications, more than 70 peer-reviewed presentations, and multiple book chapters in the field of exercise science. He has also served as a peer reviewer for over 25 professional journals, including the American Journal of Physiology, the International Journal of Exercise Science, The Journal of Strength and Conditioning Research, and the Journal of Applied Physiology. Dr. Brown’s work has also included research into the effects of testosterone supplements in men and women and competitive differences between men and women in sports.

The expert report summarizes multiple studies from around the world that demonstrate the physical advantages males experience in athletic competition. Additionally, these studies challenge the misconceptions that male physical advantages exist only after puberty and can be eliminated by testosterone suppression.

We summarize Dr. Brown’s key arguments here, but you can read his full expert report below.

Expert Report

1. In nearly every sport, men outperform women

Similarly gifted and trained males have physical advantages over females—from greater height and weight and larger, longer, and stronger bones to larger muscles, lower body fat, higher rates of metabolizing and releasing energy, and greater levels of testosterone. These innate physiological traits translate to competitive advantages for men over women. By the numbers, men have:

• 60-100% greater arm strength
• 57% greater average grip strength
• 25-60% greater leg strength
• 162% greater punching power
• 10-13% faster speed in both short and long-distance running
• 15-24% greater jumping ability

Studies have also found that men:

• Throw a baseball 35% faster than women
• Serve a tennis ball 15% faster
• Hit a golf ball 15% faster
• Throw a javelin 30% farther
• Spike a volleyball 29-34% faster
• Kick a soccer ball with 20% greater velocity
• Have 4-16% faster reaction times

As one study noted, even when male and female Olympic weightlifters of the same body weight are compared, men lift between 30% and 40% more than the women. Without comparing similar body weights, the male record is 65% higher than the female record.

2. Male athletic advantages exist even before puberty

Most of us tend to attribute male physiological advantages to the developmental changes caused by male puberty. But while boys’ physiological and performance advantages accelerate rapidly from the onset of puberty, data show that male athletic performance advantages exist well before puberty begins.

In his report, Dr. Brown points to a European study that examined the athletic performances of over 10,000 boys and girls of elementary school age. The study found that between ages 6 and 10, boys have significant advantages in speed, lower- and upper-limb strength, and cardiorespiratory fitness. In the study, the boys outperformed girls at every age in measures of handgrip strength, standing long jump, 20-m shuttle run, and predicted VO₂ max. VO₂ max refers to maximal oxygen consumption, which correlates to 30-40% of success in endurance sports.

Research on throwing distance has documented male advantages as early as 2 to 4 years of age. Multiple other studies cited by Dr. Brown show similar results in young boys and girls across athletic performances like running, bent arm hang time, vertical jump height, and throwing velocity. One longitudinal study found that boys as young as 3.5 to 4.5 years were consistently stronger than girls at every measurement point, despite no observed differences in muscle size. This strongly suggests that these differences are rooted in biology, not training. These advantages only increase once puberty begins.

3. Male athletic advantages exist even after testosterone suppression

Many athletic associations have relied on testosterone suppression in males identifying as female in an attempt to level the playing field.

But the available evidence shows that the suppression of testosterone in a male after puberty does not substantially eliminate the male athletic advantage. In fact, studies find that males retain a strong performance advantage even after lengthy testosterone suppression.

• One longitudinal study found that males who went through testosterone suppression lost only 7% hand strength after 12 months of treatment, and only a cumulative 9% after two years. (Recall that men have about 60% greater hand grip strength compared to women). Testosterone suppression did little to eliminate the male advantage.
• Another longitudinal study documented the testing of isometric strength levels measured at the knee after 12 months of testosterone suppression and found that strength levels “were maintained over the [study period].” The study also concluded that “muscle strength after 12 months of testosterone suppression was comparable to baseline strength.” As a result, those men still “remained about 50% stronger” compared to women.
• One study that measured running speed in a 1.5-mile-distance run found that before testosterone suppression, the male study group ran 21% faster than the female average. After 2 years of testosterone suppression, that same group still ran 12% faster.
• A 2025 systematic review and meta-analysis examining the effects of testosterone suppression and estrogen administration on muscle strength in males who identify as transgender women reached the same conclusion: while hormone therapy produces some reductions in muscle strength, those males generally retain strength levels significantly higher than those of comparably aged females, even after one to three years of treatment.

Thus, while testosterone suppression can modestly reduce the performance advantages that men typically have, it can’t eliminate all of them. Furthermore, suppressing testosterone doesn’t address important physiological advantages that males maintain. Even after testosterone suppression, males still retain advantages in skeletal configuration, cardiovascular performance, muscle mass, etc.

Dr. Brown concludes, “Available research enables us to sort out, in some detail, which specific physiological advantages are immutable once they occur, which can be reversed only in part, and which appear to be highly responsive to later hormonal manipulation. The bottom line is that very few of the male physiological advantages … are reversible by testosterone suppression once an individual has passed through male puberty.” And numerous international studies published in the last five years have only made this clearer.

In 2021, the government-commissioned Sports Councils of the United Kingdom conducted their own study and concluded, “[T]he latest research, evidence and studies made clear that there are retained differences in strength, stamina and physique between the average woman compared with the average transgender woman or non-binary person registered male at birth, with or without testosterone suppression.”

It’s also important to note that suppressing testosterone before puberty will likely not eliminate the advantages boys already have. As Dr. Brown notes, “[T]here is no published scientific evidence that the administration of puberty blockers to males before puberty eliminates the pre-existing athletic advantage that prepubertal males have over prepubertal females in almost all athletic events.”

A growing global consensus

The broader sports world is taking notice. World Athletics recently adopted a one-time genetic test for athletes wishing to compete in the female category. World Boxing announced mandatory sex testing for eligibility in male and female competition categories. The U.S. Olympic and Paralympic Committee updated its athlete safety policy to restrict eligibility for the female category to those whose biological sex is female. These aren’t fringe positions—they reflect a growing consensus among major sports governing bodies that protecting the female category requires biological criteria.

Dr. Brown’s report makes scientifically clear what common sense tells us: When gender identity trumps biology, women’s athletic opportunities will cease to meaningfully exist. As Dr. Brown summarizes, whether at the elite, collegiate, scholastic, or recreational levels, males will retain a competitive advantage over “equally gifted, aged, and trained” females, with or without testosterone suppression. Scientific research continues to point to the necessity of creating policies that will protect women’s athletic opportunities and ensure women and girls are not forced to compete against men.