A newly published study in the British Journal of Sports Medicine adds fresh data to ongoing debates over transgender participation in sport, concluding that while body composition differences exist, measures of physical fitness between transgender and cisgender adults are largely comparable.
The study, released January 22, 2026, is a systematic review and meta-analysis examining previously published research on body composition and physical fitness outcomes in transgender adults compared with cisgender men and women. Researchers analyzed data on lean body mass alongside functional fitness indicators such as strength and aerobic capacity.
According to the authors, transgender women were found to have higher absolute lean mass than cisgender women. However, when researchers examined performance-based fitness measures rather than anatomical metrics alone, the results did not show consistent or statistically significant differences between the groups.
The distinction is notable because much public discourse around transgender athletes has focused heavily on muscle mass as a proxy for athletic performance. The authors emphasized that lean mass alone does not reliably predict real-world physical performance, particularly across varied sports and training conditions.
When looking at indicators such as cardiovascular endurance and strength testing, the review found overlapping performance ranges between transgender women and cisgender women. In several cases, differences were small or inconsistent across studies. Researchers noted that training history, testing methods, and participant characteristics varied widely, limiting broad conclusions.
The authors also cautioned that the overall evidence base remains limited. Many of the studies included were small, observational, or lacked standardized testing protocols. As a result, the findings should be interpreted carefully and not overstated in policy discussions.
Despite those limitations, the study contributes to a growing body of research suggesting that assumptions about inherent athletic advantage based solely on sex assigned at birth are overly simplistic. The authors argue that athletic performance is influenced by multiple factors, including training intensity, access to coaching, nutrition, and socioeconomic conditions.
The researchers called for more rigorous and sport-specific studies that evaluate physical performance outcomes rather than relying primarily on anatomical measurements. They also emphasized the need for research that accounts for hormone therapy duration, age, and level of athletic participation.
As sports governing bodies around the world continue to revisit eligibility policies for transgender athletes, the authors suggest that evidence-based approaches should distinguish between physical capacity and anatomical characteristics. They argue that fitness, not assumptions, should remain central to any fair and inclusive policy framework.
The study arrives amid increasing political pressure on sports organizations to restrict transgender participation, often citing claims of competitive imbalance. This latest analysis adds nuance to that discussion by reinforcing that fitness outcomes cannot be inferred from body composition alone.
