In recent years, discussions surrounding the participation of transgender athletes in competitive sports have intensified, drawing attention to the complexities of body composition and physical performance across gender identities. A systematic review published in the British Journal of Sports Medicine aims to shed light on these issues by analyzing a variety of studies related to transgender and cisgender individuals. This review is particularly relevant at a time when sports organizations are striving to balance inclusivity with fairness.
The review analyzed data from 52 studies that included 6,485 participants—transgender women and men, as well as cisgender men and women—spanning a broad age range, from teenagers to young adults. Given the variety of methodologies used in these studies—ranging from prospective cohorts to randomized controlled trials—the findings illuminate important trends. However, it is crucial to note that many studies varied in their quality, with few focusing on key functional fitness parameters and even fewer accounting for confounding factors such as hormone levels, initial fitness, and nutrition.
A significant finding from this analysis is related to body composition. Transgender women who have undergone one to three years of hormone therapy show increased body fat percentages, aligning more closely with those of cisgender women, but they maintain greater lean muscle mass compared to cisgender women. Nonetheless, this does not appear to translate into enhanced upper or lower body strength, suggesting that while muscularity may differ, it does not necessarily confer a competitive advantage.
When it comes to physical performance, transgender women exhibit cardiorespiratory fitness, measured by maximal oxygen consumption (VO₂ max), similar to that of cisgender women, and significantly lower than that of cisgender men. These results challenge assumptions that prior testosterone exposure guarantees enduring athletic superiority, even after switching to hormone therapy. However, caution is advised in interpreting these findings due to variability in study duration, participant demographics, and the specific sports examined.
The review points out that hormone therapy leads to notable physiological changes, increasing fat mass and reducing muscle mass in transgender women while having the opposite effects in transgender men. This hormonal influence can impact both structural and functional fitness. Yet, questions remain about how quickly these adaptations stabilize and how they affect eligibility for competitive sports, especially among elite athletes.
One significant limitation identified is the lack of representation of athletes actively engaged in competitive sports. The scarcity of information on high-performance transgender athletes makes it difficult to formulate data-driven policies. Moreover, essential factors such as training types, duration of puberty suppression, and prior hormone exposure have often been inconsistently reported, emphasizing the need for ongoing research that focuses on performance outcomes specific to athletic excellence.
Another intriguing concept in need of investigation is “muscle memory,” which refers to the idea that muscle adapted from previous training may retain some performance advantages despite hormonal changes. Understanding how these adaptations affect competitive fairness is critical. Researchers recommend developing sophisticated studies that examine various physiological markers among transgender athletes to thoroughly explore this subject.
Despite the challenges highlighted, the study refutes the notion of blanket bans on transgender women participating in women’s sports categories. The overlap in key performance metrics with those of cisgender women suggests that assumptions regarding inevitable competitive advantages are not substantiated by empirical data. Policymakers are encouraged to develop nuanced frameworks that consider new scientific findings while prioritizing ethical considerations of inclusion and fairness.
Looking forward, the authors emphasize the need for comprehensive, long-term studies that track transgender athletes across different sports and competitive levels. Such research should include thorough assessments of physical fitness, hormonal profiles, training backgrounds, and psychological factors. Only through this multifaceted approach can we generate the necessary evidence to inform policies that respect both athletic integrity and individual dignity.
In summary, this significant systematic review expands our understanding of the physiological differences between transgender athletes post-hormone therapy and contributes to the ongoing dialogue around fairness and inclusion in sports. It reveals the limitations within current research while establishing a foundation for future inquiries. As this conversation evolves, a continued commitment to scientific investigation and ethical dialogue will be crucial in addressing the complex relationship between biology, identity, and competition.
Subject of Research: Body composition and physical fitness comparisons between transgender and cisgender individuals, particularly focusing on the impact of gender-affirming hormone therapy.
Article Title: Body composition and physical fitness in transgender versus cisgender individuals: a systematic review with meta-analysis.
News Publication Date: February 3, 2026.
Web References: https://dx.doi.org/10.1136/bjsports-2025-110239
Keywords: Transgender identity, Sports, Gender identity, Body composition, Physical fitness, Hormone therapy, Athletic performance, VO₂ max, Muscle mass, Muscle memory.
Tags: body composition differences, transgender, cisgender, women sports participation, fairness in athletic competition, gender-affirming hormone therapy effects, hormone therapy impact on fitness, inclusion in women’s sports, meta-analysis of transgender athletes, physical fitness in transgender individuals, sports policy and transgender athletes, systematic review of fitness studies, transgender women athletic performance.
