Trans athletes may not have fitness advantage in women's sport, study finds

A pooled review of about 50 studies found transgender women had similar strength and aerobic fitness to cisgender women months to years after starting hormone therapy, while body composition measures showed differences between groups.

Brazilian researchers published a pooled review examining how gender-affirming hormone therapy relates to body composition and physical fitness in transgender people. They combined results from roughly 50 studies involving about 6,485 participants aged about 14 to 41, including trans women, trans men and cisgender comparison groups. The review found that although trans women showed differences in body composition compared with cis men and cis women, measures of strength and aerobic capacity tended to be similar to those of cis women months to years after starting hormone therapy. The authors note limitations in the available evidence and call for more long-term, performance-focused research. Key findings: - The review included about 50 studies with a total of roughly 6,485 participants: 2,943 trans women, 2,309 trans men, 568 cis women and 665 cis men; reported ages ranged from about 14 to 41. - Trans women had higher body fat than cis men, but fat levels were similar to those of cis women. - Trans women appeared to have greater muscle mass in pooled measures, yet no clear differences were observed in upper- or lower-body strength compared with cis women. - No consistent difference was found in maximal oxygen consumption (VO₂ max) between trans women and cis women in the pooled analysis. - Trans men after one to three years of hormone therapy showed reduced fat, increased muscle mass and greater measured strength. - Researchers highlighted study limits: most data focused on physiological outcomes, few studies included adolescents or examined social and psychological factors, and topics such as "muscle memory" remain under-studied. Summary: The pooled review indicates that functional measures of strength and aerobic fitness in transgender women tend to converge with those of cisgender women after months to years of hormone therapy, despite some residual differences in body composition. Authors and outside experts say the findings contribute important data but are not definitive, noting gaps such as limited adolescent data and a need for sport-specific performance research. Researchers call for longer-term studies prioritizing performance metrics and broader participant demographics to better inform policy discussions.