In a groundbreaking systematic review published in the British Journal of Sports Medicine, researchers have undertaken a comprehensive examination of existing studies to elucidate the nuanced differences in body composition and physical performance between transgender and cisgender individuals. The study addresses a highly contentious and socially significant debate: the athletic participation of transgender women in female sports categories. Through meticulous meta-analysis, the findings challenge prevailing assumptions about inherent athletic advantages attributed to transgender women following gender-affirming hormone therapy. This research emerges at a time when policymakers and sports governing bodies grapple with balancing inclusion, fairness, and scientific rigor.
The review incorporated data from 52 studies encompassing 6,485 participants, including transgender women, transgender men, and cisgender men and women across a wide age range from adolescence to early adulthood. This heterogeneous dataset included diverse methodologies ranging from prospective and retrospective cohorts to randomized controlled trials and quasi-experimental designs. Importantly, the collected studies varied widely in their scope and quality, with only a fraction assessing functional physical fitness parameters, and fewer still adjusting for confounding variables such as hormone levels, baseline fitness, or nutritional status.
A major revelation from the pooled analysis lies in the body composition metrics. Transgender women, one to three years post hormone therapy initiation, exhibited increased body fat percentages relative to cisgender men, approximating levels observed in cisgender women. Concurrently, transgender women maintained higher lean muscle mass compared to cisgender women, although this did not translate into superior upper or lower body strength. This divergence between muscularity and functional strength suggests the possibility of residual musculoskeletal differences that may not confer an athletic edge.
Physical performance assessments provided further clarity on this complex issue. Transgender women demonstrated similar cardiorespiratory fitness, as quantified by maximal oxygen consumption (VO₂ max), relative to cisgender women, and significantly lower values compared to cisgender men. This convergence in aerobic capacity, alongside comparable muscle strength metrics, contradicts widely held notions positing that previous testosterone exposure assures lasting athletic superiority, even after hormone suppression. Nonetheless, these findings should be interpreted cautiously given the variability in study duration, participant demographics, and sport disciplines investigated.
The review highlights that hormone therapy drives marked physiological changes, leading to increased adiposity and reduced muscle mass in transgender women, while inducing opposing effects in transgender men. This hormonal modulation influences both structural and functional fitness outcomes, illustrating the dynamic interplay between endocrine transition and physical capability. However, the timeline over which these adaptations stabilize—and their implications for competitive sports eligibility—remain inadequately characterized, particularly in elite athlete populations.
Critical gaps permeate the current literature, most notably the under-representation of athletes actively engaged in competitive sports. The scarcity of data on high-performance transgender individuals complicates efforts to formulate evidence-based policies. Additionally, crucial variables such as training regimens, duration and timing of puberty suppression, and prior hormone exposure have often been inconsistently reported or controlled for. These omissions underscore the necessity for longitudinal, performance-centric research paradigms designed to isolate the physiological effects pertinent to athletic excellence.
Furthermore, the concept of ‘muscle memory’—the capacity for previous training adapted muscle to retain some functional advantages even after hormonal alterations—remains insufficiently explored in this context. The potential for long-term retention of neuromuscular adaptations acquired prior to hormone therapy could influence competitive fairness assessments. Researchers advocate for sophisticated studies incorporating molecular, biomechanical, and physiological markers to delineate this phenomenon’s scope among transgender athletes.
Despite these challenges, the study conclusively pushes back against blanket prohibitions on transgender women’s participation in female sports categories. The convergence of key performance measures with cisgender women indicates that simplistic assumptions about unavoidable competitive advantages lack empirical substantiation. Policymakers are urged to adopt nuanced frameworks that integrate emerging scientific insights alongside ethical considerations of inclusion and equity.
Moving forward, the study authors emphasize the imperative for robust, well-controlled investigations that monitor transgender athletes longitudinally across various sports disciplines and competitive tiers. Such research should integrate comprehensive assessments of physical fitness, hormone profiles, training histories, and psychosocial factors. Only through this multidimensional approach can the scientific community generate the evidence necessary to inform policies that uphold both athletic integrity and human dignity.
In sum, this landmark systematic review reframes our understanding of transgender athletes’ physiological profiles post hormone therapy, augmenting the discourse around fairness and inclusion in sports. It exposes the deficiencies inherent in the current evidence base while laying the groundwork for future rigorous investigation. As the dialogue evolves, sustained commitment to scientific inquiry and ethical stewardship will be paramount in navigating this complex intersection of 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 cisgendercisgender women sports participationfairness in athletic competitiongender-affirming hormone therapy effectshormone therapy impact on fitnessinclusion in women’s sportsmeta-analysis of transgender athletesphysical fitness in transgender individualssports policy and transgender athletessystematic review of fitness studiestransgender women athletic performance
