Health & Medicine
What Is Gender Dysphoria, and What Does the Evidence Actually Show?
The diagnosis, the treatments and the outcome studies.
Groups & Crime
Are Trans People More Likely to Be Victims of Crime?
Survey rates, hate crime counts and what the prison figures show.
Groups & Crime
Are Trans People Overrepresented as Mass Shooters?
The claim against the three shooter databases.
Do Trans Women Retain an Athletic Advantage?
The claim is that trans women who went through male puberty keep an athletic advantage over other women even after they lower their testosterone. This page tests it trait by trait against the studies of fitness and performance, and sets out what the sports bodies have decided.
Jump to the verdict ↓
What this covers
This covers adults who went through male puberty and began hormone therapy as adults. It does not cover anyone who took puberty blockers before or during puberty, which is a different question. Nor does it cover athletes with differences of sex development (DSD), such as Caster Semenya, whose case concerned World Athletics' separate rules for DSD athletes.
The short answer
It depends what you count. Hormone therapy brings haemoglobin, which carries oxygen in the blood, down to cisgender women's levels within about four months. Muscle shrinks only about 5 percent in the first year and stays above cisgender women's average for at least three years, and the skeleton does not change. Whether that adds up to an advantage in sport is not settled: the studies of fitness and performance are few, mostly of non-athletes, and point different ways.
What is actually being asked
Male puberty confers athletic advantage, so that is not the claim in dispute. In a 2018 paper, Handelsman and colleagues put the overall advantage at "at least" 8 to 12 percent.
The dispute is what happens to that advantage when an adult suppresses testosterone. One side treats advantage as a function of circulating hormones, so lowering testosterone should remove it. The other treats it as a function of development, so what puberty built stays built. Both are partly right, because different traits behave differently.
Some traits track current hormone levels closely. Some track them slowly. Some do not track them at all.
What reverses, and quickly
Blood is the clearest case. Testosterone drives red blood cell production. When it is suppressed, haemoglobin and haematocrit (red blood cells' share of total blood volume) fall to the range typical of cisgender women. Harper and colleagues, reviewing twenty-four studies, put the timeline at about four months.
A measure that fully normalises
Haemoglobin and haematocrit reach cisgender women's levels, not merely approach them, and Harper and colleagues describe the fall as rapid. Higher haemoglobin is an established aid to endurance, so the fall may cut into an endurance advantage early, as Harper and colleagues suggest. How much has not been measured: haemoglobin is only one of the things that set aerobic capacity.
What changes slowly, and what that means depends on the denominator
Muscle is the contested middle. Hilton and Lundberg count twelve longitudinal studies of lean mass or muscle size in trans women, which together show about a 5 percent loss after twelve months of suppression. Lean mass, a stand-in for muscle, is the body's weight without its fat and, as X-ray body scans measure it, its bone. Fat-free mass, a close measure, leaves out only the fat.
Wiik and colleagues followed eleven trans women. At one year they measured thigh muscle volume down 5 percent and quadriceps cross-sectional area down 4 percent, with knee extensor strength holding steady.
Over three years Gooren and Bunck recorded a 12 percent fall in thigh muscle area, as Hilton and Lundberg report it. The longest follow-up, by Lundberg and colleagues, measured 16 trans women before treatment and after one and five years, though many dropped out before the end. At five years their thigh muscle volume was 7 percent lower and their knee strength had not changed. Their strength stayed well above female reference values.
Hilton and Lundberg put strength differences between the sexes at 30 to 100 percent, depending on the cohort and the task. They put the performance gap at 10 to 50 percent, depending on the sport. Subtracting a 5 percent loss from a baseline of that size leaves most of it in place on paper. That subtraction is the heart of the retained-advantage argument, and in absolute terms it holds. Hilton and Lundberg's review and Harper and colleagues' review, both from 2021, concluded that lean mass, muscle area and strength remain above cisgender women's averages at three years.
Why the same data produces opposite headlines
Hamilton and colleagues, in a study funded by the International Olympic Committee (IOC), tested trained athletes. Absolute grip strength was higher in trans women than in cisgender women, 40.7 kg against 34.2 kg, but scaled to fat-free mass or to hand size the difference disappeared. In the same cohort, jump height per kilogram of fat-free mass was lower, 0.7 against 1.0 centimetres. Relative oxygen uptake was lower too, 45.1 against 54.1 millilitres per kilogram per minute.
Alvares and colleagues, testing non-athletes, found absolute oxygen uptake and grip strength both higher in trans women than cisgender women and both lower than in cisgender men, an intermediate pattern. Scaled to fat-free mass, trans women's oxygen uptake and grip strength were below cisgender women's, but neither difference was statistically significant.
Anyone citing a single strength or fitness number is choosing a denominator. The absolute figures favour the retained-advantage case. The body-mass-relative figures favour the inclusion case. Both are in the same papers.
Download this conclusion: one study, two answers
This section as one image. In Hamilton's trained athletes, trans women's absolute grip strength was 19 percent above cisgender women's. But their jump height per kilogram of fat-free mass was 30 percent lower, and their oxygen uptake per kilogram 17 percent lower.
What does not change at all
Height, limb length, bone geometry, hand and foot size and overall frame are set by puberty and are not altered by adult hormone therapy. Hilton and Lundberg reach this conclusion directly: there is no plausible mechanism by which testosterone suppression would change bone length or hip width. They add that trans women generally maintain bone mass across at least 24 months of suppression. They say the retained skeletal advantage matters especially in sports where height, limb length and handspan are key, giving basketball, volleyball and handball as examples.
These traits matter differently by sport. Longer levers help where force goes through a limb, as in throwing and striking, and the male-female gaps are widest in those events.
The baseline gap, sport by sport
How much the male advantage is worth depends on the event, and the spread is wide. Hilton and Lundberg put the gap between cisgender men and cisgender women at 11 to 13 percent in rowing, swimming and running. They put it at 31 to 37 percent in Olympic weightlifting and over 50 percent in a baseball pitch and a field hockey drag flick. Those gaps are male-female baselines, not measurements of trans women, and they are the starting point the hormone therapy decline is subtracted from.
The range is the finding: “does an advantage persist” has no single answer across sports.
The strongest case that advantage persists
Put at its strongest: male puberty builds a skeleton that hormone therapy cannot remodel. It also builds muscle that hormone therapy reduces by only about 5 percent in the first year. The decline slows sharply after year one and appears to settle above cisgender women's average rather than reaching it.
The field data support this case in part. Two studies have used the US Air Force's fitness test records. Roberts and colleagues followed 46 trans women and compared them with the average for airwomen under 30. Before hormone therapy the trans women did 46 percent more push-ups in a minute than that average and 17 percent more sit-ups. They ran 1.5 miles 21 percent faster.
Their run advantage lasted longest. Roberts and colleagues put it at 9 percent after one year of suppression, the period World Athletics then required. After two years the push-up and sit-up differences were no longer statistically significant, but the trans women still ran 12 percent faster.
A larger study of the same service's records, by Chiccarelli and colleagues, tracked trans women for up to four years. By the count of a 2024 review by Cheung and colleagues, it tracked 228 of them, of whom 15 were still in the data at four years. It found the run advantage gone by two years and the sit-up advantage by four, while push-ups stayed above the female average at four years.
Cheung and colleagues' review notes that those who stay in the military are likely to be fitter than those who leave, which could bias both studies.
US Air Force fitness tests: trans women against the average for airwomen under 30, before and after hormone therapy
How to read it: each bar is how far trans women's average was above the average for airwomen under 30 on that test, in percent. The darker bar is before hormone therapy and the lighter bar after two to two and a half years of it. A bar below zero means below the female average. After two years only the run difference was statistically significant.
Source: Roberts, Smalley and Ahrendt, British Journal of Sports Medicine 2021, table 4; 46 trans women in the US Air Force. The percentages divide each gap by the female average; the paper's own summary gives 31 and 15 percent for push-ups and sit-ups, dividing by the trans women's scores instead.
| Test | Female average | Trans women, before hormone therapy | Trans women, after 2 to 2.5 years |
|---|---|---|---|
| Push-ups in 1 minute | 32.5 | 47.3 (+46%) | 34.6 (+6%, not significant) |
| Sit-ups in 1 minute | 45.6 | 53.5 (+17%) | 44.8 (−2%, not significant) |
| 1.5-mile run, seconds | 855 | 708 (21% faster) | 765 (12% faster) |
The precautionary version of the argument is that where a retained advantage cannot be ruled out, the burden should fall on inclusion, not on the women already in the category. That is a judgement about which error to risk, not a claim about the data, and it should be argued on those terms.
The strongest case that advantage does not persist
Put at its strongest: the subtraction behind the retained-advantage argument is not arithmetic anyone is entitled to do. The baseline gap comes from comparing elite cisgender men with elite cisgender women. The 5 percent decline comes from small clinical studies of trans women who were not athletes. The two numbers describe different populations measured different ways, and subtracting the decline from the baseline gap assumes trans women start at cisgender men's average.
In clinical studies, trans women did not start there. Two studies reviewed by Harper and colleagues found 6 and 8 percent less lean mass in trans women before treatment than in cisgender men. One found 14 percent less grip strength. In the Air Force records, trans women before treatment matched the male average on sit-ups and the run, but not on push-ups.
Fifty studies pooled
Sieczkowska and colleagues pooled 50 studies covering 6,099 people, in the corrected version of their 2026 meta-analysis, and compared trans women against cisgender women directly. None of the five measures they compared reached statistical significance. For upper-body strength, the confidence interval ran from minus 0.52 to 2.35, wide enough to include a large advantage and a deficit.
Trans women carried higher absolute lean mass, but relative lean mass, relative fat mass, strength and aerobic capacity were all comparable. The authors grade the evidence very low to low certainty and say it does not support theories of inherent athletic advantage for trans women. The paper has been corrected twice since publication, and the figures here are from the corrected version. The 52 studies and 6,485 people reported in the press coverage are from the original.
Trans women against cisgender women: standardised mean differences from the 2026 meta-analysis (Sieczkowska and colleagues, corrected version)
How to read it: each bar is a standardised mean difference between trans women on hormone therapy and cisgender women. Zero means no difference, a bar to the right means trans women measured higher, and a bar to the left lower. By the convention of the psychologist Jacob Cohen, 0.2 is a small difference and 0.8 a large one. None of the five reached statistical significance.
Source: Sieczkowska and colleagues, British Journal of Sports Medicine 2026, corrected version, 50 studies and 6,099 people.
| Measure | Standardised mean difference | 95% confidence interval | Certainty of the evidence |
|---|---|---|---|
| Upper-body strength | 0.92 | −0.52 to 2.35 | Very low |
| Relative lean mass | 0.19 | −0.14 to 0.53 | Low |
| Lower-body strength | −0.10 | −1.07 to 0.86 | Very low |
| Maximal oxygen uptake | −0.28 | −0.81 to 0.25 | Very low |
| Relative fat mass | −0.29 | −0.63 to 0.05 | Very low |
Hamilton's study of trained athletes goes further on the measures scaled to body size. Its trans women jumped lower and took up less oxygen per kilogram than cisgender women athletes. Their lung function ratio, the share of a forced breath's air breathed out in its first second, was lower too.
The studies that follow trained athletes through transition are small. The latest, by Harper and colleagues in 2025, gathered race times for nine trans women runners and one swimmer. The runners' times slowed by 14.6 percent on average after a mean of 31 months of hormone therapy. Scored against runners of the same age and sex, men before and women after, they rated the same.
The swimmer slowed by 5.2 percent. Even so, in the 500 yards the swimmer went from 65th in the men's National Collegiate Athletic Association (NCAA) Division I rankings to first in the women's.
Download this conclusion: the meta-analysis
This section as one image. It gives the 2026 meta-analysis's differences against cisgender women, none of them significant: upper-body strength 0.92, relative lean mass 0.19, lower-body strength minus 0.10 and maximal oxygen uptake minus 0.28. It adds the two cautions its authors attach.
What the governing bodies decided, and on what
Sports bodies have not waited for better evidence. In 2021 the International Olympic Committee (IOC) dropped its single testosterone threshold, established that there should be no presumption of advantage, and pushed eligibility down to individual federations. Several of the largest federations then went the other way.
World Aquatics in June 2022 restricted the women's category to those who had not experienced male puberty beyond its onset (Tanner stage 2) or age 12, whichever came later. It also set out to study an open category, but when one was piloted at a World Cup meet in Berlin in October 2023, nobody entered.
World Athletics announced on 23 March 2023 that it would exclude trans women who had been through male puberty from female world ranking competition, effective 31 March. Its president, Sebastian Coe, described its council's reasoning. Where the science was insufficient to justify a testosterone rule, he said, the council had to be guided by its overarching principle of protecting the female category. With no transgender athletes then competing internationally, World Athletics said, there was no athletics-specific evidence, so it put fairness before inclusion.
Cycling's Union Cycliste Internationale followed in July 2023. It said the science did not confirm that two years of suppression removed the benefits of male puberty. It added that a lasting advantage from the shape and arrangement of the limb bones could not be ruled out. The National Collegiate Athletic Association (NCAA) limited women's competition to athletes assigned female at birth in February 2025, one day after a presidential executive order on the subject.
Since September 2025, World Athletics has required a once-in-a-lifetime test for the sex-determining region Y (SRY) gene, found on the Y chromosome that boys and men typically carry. In March 2026 the IOC reversed its 2021 position. From the 2028 Los Angeles Games, the same screen will decide eligibility for its female events, with exceptions for rare conditions such as complete androgen insensitivity. Both rules keep all trans women out of the female category.
What the bans rest on
The bodies that gave reasons pointed to what male puberty builds and to what suppression could not be shown to remove. World Aquatics' science advisers went further, finding that male puberty leaves "persistent legacy effects" that give trans women an advantage. None cited results showing trans women winning out of proportion.
There are few to cite: Laurel Hubbard, a weightlifter, at Tokyo in 2021, is the only openly transgender woman known to have competed at an Olympics. The NCAA's own president told the Senate in December 2024 that of more than 500,000 student athletes he was aware of fewer than ten who were transgender.
The state of the evidence
This literature is thin enough that anyone claiming it settles the question is overstating it. Most studies are small. Wiik studied 11 trans women and Alvares 15. Hamilton studied 23 and Roberts 46. Most of the longitudinal physiology comes from clinical populations who were not athletes, while the question is about competitive sport. Hamilton's is the main laboratory study of trained athletes, and it is cross-sectional, so it cannot establish a time course.
The reviews rest heavily on the same small studies, so agreement between them reflects shared source data rather than independent confirmation. And the designs answer different questions: longitudinal studies measure how much trans women lose from their own starting point, while cross-sectional studies compare them with cisgender women at one moment.
Some things are barely studied. A 2024 review by Cheung and colleagues found no published research on hormone therapy's effect on cardiac size, lung function, anaerobic capacity, lactate threshold or exercise economy. Longitudinal studies are rare and often stop at one or two years. The five-year study by Lundberg and colleagues is an exception. And few trans women have competed at elite level, so there are almost no elite results to study.
The verdict: what the evidence shows
It depends what you count. Haemoglobin follows hormone levels and reaches cisgender women's range within about four months. Muscle follows them only partly: it falls about 5 percent in the first year and stays above cisgender women's average for at least three years. In a study that followed trans women for five years, strength had not changed. The skeleton does not follow hormone levels at all.
Whether those traits add up to an advantage in sport is not settled. A 2026 meta-analysis of 50 studies found no statistically significant gap in strength or aerobic fitness against cisgender women, at very low certainty. The two Air Force studies disagree about running, and few trans women have competed at elite level.
The common subtraction, the male advantage minus the decline under hormone therapy, holds for the skeleton and points the right way for muscle in absolute terms. But it is not reliable arithmetic: the two figures come from different populations measured different ways.
Four common claims, against the evidence
Claim“Lowering testosterone removes the advantage.”
Only in partHaemoglobin reaches cisgender women's levels within about four months. But muscle falls only about 5 percent in the first year and stays above cisgender women's average for at least three years. The skeleton does not change.
Claim“Trans women keep their whole male advantage.”
Not shownMuscle and haemoglobin fall. Scaled to body size, trained trans women in the main laboratory study jumped lower and took up less oxygen per kilogram than cisgender women athletes.
Claim“The research shows trans women have no advantage.”
Not shownA 2026 meta-analysis of 50 studies found no statistically significant gap against cisgender women, but rated the evidence very low to low certainty, and absolute lean mass was higher.
Claim“Trans women are winning women's sport.”
No dataFew trans women have competed at elite level, so there are almost no elite results to test the claim. The president of the National Collegiate Athletic Association knew of fewer than ten transgender athletes among more than 500,000 student athletes.
Download the conclusion
The verdict above as one image. Its chart gives Roberts and colleagues' before-and-after Air Force figures: how far trans women were above the female average on push-ups and the run. Before hormone therapy the gaps were 46 and 21 percent. After two years they were 6 percent (not significant) and 12 percent. A larger study of the same tests found no run difference by two years. It is 1,080 by 1,350 pixels, and anyone may download it and post it.
What would change this conclusion
This article concludes that: (1) hormone therapy brings haemoglobin to cisgender women's levels within about four months; (2) muscle falls about 5 percent in the first year and stays above cisgender women's average for at least three years; (3) the skeleton does not change; (4) whether these traits add up to an advantage in sport is not settled, because the studies that measure performance are few, small or mostly of non-athletes, and disagree.
These conclusions would be falsified by:
• A longitudinal study of more than 100 trained trans women, with matched cisgender women athletes, measuring performance rather than laboratory proxies
• Elite competition results showing trans women winning out of proportion across a sport, or failing to
• Larger studies following muscle and strength past three years that find them falling to cisgender women's levels
• A larger trained cohort in which grip strength scaled to fat-free mass and hand size again shows no difference from cisgender women, or shows one
Sports bodies could fund the studies of trained athletes, as the International Olympic Committee funded Hamilton's. Hospital clinics that treat trans women could follow more of them for longer, as Lundberg and colleagues did in Stockholm. Elite results can come only from competitions that let trans women enter female events.
Sources
Sieczkowska S.M., Mazzolani B.C., Coimbra D.R., Longobardi I., Casale A.R., da Hora J.D.F.V.M.P., Roschel H. & Gualano B. (2026). Body composition and physical fitness in transgender versus cisgender individuals: a systematic review with meta-analysis. British Journal of Sports Medicine 60(3), 198-210, published 11 February 2026 and corrected twice since (DOI 10.1136/bjsports-2025-110239corr1 and corr2). DOI 10.1136/bjsports-2025-110239. PROSPERO CRD42024562210. 50 studies, n=6,099 in the corrected version; the original reported 52 studies and n=6,485. Source for the standardised mean differences against cisgender women in the corrected version (upper-body strength 0.92, 95% CI −0.52 to 2.35; lower-body strength −0.10, −1.07 to 0.86; maximal oxygen consumption −0.28, −0.81 to 0.25; relative lean mass 0.19, −0.14 to 0.53; relative fat mass −0.29, −0.63 to 0.05), the certainty grading and the authors' conclusion. Its preprint, Physical Fitness and Body Composition in Transgender vs. Cisgender Individuals: A Systematic Review and Meta-Analysis (medRxiv, May 2025, DOI 10.1101/2025.05.05.25326994), is the source for the higher lean mass being absolute lean mass. doi.org doi.org
News-Medical (2026). New meta-analysis challenges claims of athletic advantage for transgender women. 6 February 2026; and Science Media Centre Spain (2026), A review finds no differences in physical performance between trans women and cis women, even though they have more muscle mass, 4 February 2026. Source for the original version's 52 studies and 6,485 people as the press reported them. news-medical.net sciencemediacentre.es
Harper J., O'Donnell E., Sorouri Khorashad B., McDermott H. & Witcomb G.L. (2021). How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation. British Journal of Sports Medicine 55(15), 865-872. DOI 10.1136/bjsports-2020-103106. Twenty-four studies reviewed. Source for haematocrit as the volume of red blood cells compared with total blood volume, for the four-month haemoglobin timeline and for the finding that strength, lean body mass and muscle area remain above cisgender female values even after 36 months, and for the reviewed studies of hormone-naive trans women against cisgender men (6.4 and 8.0 percent less lean mass, 14 percent less grip strength). doi.org europepmc.org
Hilton E.N. & Lundberg T.R. (2021). Transgender women in the female category of sport: perspectives on testosterone suppression and performance advantage. Sports Medicine 51(2), 199-214. DOI 10.1007/s40279-020-01389-3. Source for the sport-by-sport baseline gaps (rowing, swimming and running 11 to 13 percent; Olympic weightlifting 31 to 37 percent; baseball pitch and field hockey drag flick over 50 percent), for strength differences of 30 to 100 percent depending on cohort and task, for the roughly 5 percent first-year decline drawn from twelve longitudinal studies, for Gooren and Bunck's 12 percent thigh muscle loss over three years in 19 trans women, for the conclusion that height and skeletal parameters remain unaltered, for throwing as the widest sex difference in motor performance, and for the IOC's 2015 criteria (testosterone below 10 nmol/L for at least 12 months). springer.com
Lundberg T.R., Tryfonos A., Eriksson L.M.J., Rundqvist H., Rullman E., Holmberg M., Maqdasy S., Linge J., Leinhard O.D., Arver S., Andersson D.P., Wiik A. & Gustafsson T. (2025). Longitudinal changes in regional fat and muscle composition and cardiometabolic biomarkers over 5 years of hormone therapy in transgender individuals. Journal of Internal Medicine 297(2), 156. DOI 10.1111/joim.20039. 16 transgender women at the start, with a high dropout by five years. Source for thigh muscle volume 7 percent lower at five years, isometric knee extension strength unchanged and above female reference values, and longitudinal studies being rare and often limited to one or two years. doi.org europepmc.org
Hamilton B. et al. (2024). Strength, power and aerobic capacity of transgender athletes: a cross-sectional study. British Journal of Sports Medicine 58, 586-597. DOI 10.1136/bjsports-2023-108029. n=23 transgender women, 21 cisgender women, 12 transgender men, 19 cisgender men. Funded by a research grant from the International Olympic Committee. Source for absolute grip strength (40.7 against 34.2 kg) and its disappearance when scaled to fat-free mass or hand size, jump height per kilogram of fat-free mass (0.7 against 1.0 cm), relative oxygen uptake (45.1 against 54.1 mL/kg/min) and the lung function ratio, forced expiratory volume in one second over forced vital capacity (0.83 against 0.88), all in trained athletes. doi.org europepmc.org
Roberts T.A., Smalley J. & Ahrendt D. (2021). Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators. British Journal of Sports Medicine 55, 577-583. DOI 10.1136/bjsports-2020-102329. US Air Force cohort, n=46 transgender women and 29 transgender men. Source, from table 4, for the trans women's push-ups, sit-ups and 1.5-mile run times before treatment and after 2 to 2.5 years, the female averages they were compared with, the significance of each gap, and the percentages calculated from them; for the authors' figure of a 9 percent faster run after one year; and for the trans women's scores against the male average before treatment. doi.org
Chiccarelli E., Aden J., Ahrendt D. & Smalley J. (2023). Fit transitioning: when can transgender airmen fitness test in their affirmed gender? Military Medicine 188(7-8), e1588-e1595. DOI 10.1093/milmed/usac320. US Air Force fitness test records from one year before to four years after the start of hormone therapy. Source for the run advantage ending by two years, the sit-up advantage by four, and push-ups still above the female average at four years. doi.org
Cheung A.S., Zwickl S., Miller K., Nolan B.J., Wong A.F.Q., Jones P. & Eynon N. (2024). The impact of gender-affirming hormone therapy on physical performance. Journal of Clinical Endocrinology and Metabolism 109(2), e455. DOI 10.1210/clinem/dgad414. Source for the Chiccarelli study's 228 transgender women and 15 at four years, the effect of dropout on both Air Force studies, the absence of published research on cardiac size, lung function and other measures, few trans people having competed at elite level, and the Alvares oxygen uptake per kilogram of fat-free mass (table 2). doi.org europepmc.org
Harper J., Blagrove R.C., Hunsicker E., Witcomb G.L., Ferguson R.A. & O'Donnell E. (2025). Longitudinal performance changes in transgender women athletes pre and post gender affirming hormone therapy. European Journal of Sport Science 25(9), e70036. DOI 10.1002/ejsc.70036. Nine runners and one swimmer. Source for race times 14.6 percent slower after a mean of 31 months, age-grade scores unchanged, the swimmer's 5.2 percent and her NCAA Division I ranking, and the two earlier studies of trans athletes. doi.org europepmc.org
Wiik A. et al. (2020). Muscle strength, size and composition following 12 months of gender-affirming treatment in transgender individuals. Journal of Clinical Endocrinology and Metabolism 105(3), e805-e813. DOI 10.1210/clinem/dgz247. n=11 transgender women. Source for the thigh volume and quadriceps figures and for maintained knee extensor strength. doi.org
Alvares L.A.M., Santos M.R., Souza F.R., Santos L.M., Mendonça B.B., Costa E.M.F., Alves M.J.N.N. & Domenice S. (2022). Cardiopulmonary capacity and muscle strength in transgender women on long-term gender-affirming hormone therapy: a cross-sectional study. British Journal of Sports Medicine 56(22), 1292-1298, with a published correction (DOI 10.1136/bjsports-2021-105400corr1). DOI 10.1136/bjsports-2021-105400. 15 non-athlete transgender women on hormone therapy for an average of 14.4 years, against cisgender women and men. Source for the intermediate pattern: peak oxygen uptake 2,606 mL/min in trans women against 2,167 in cisgender women and 3,358 in cisgender men, and grip strength 35.3 kg against 29.7 and 48.4. The figures scaled to fat-free mass come from Cheung and colleagues' review (table 2) and the authors' 2022 conference abstract (Endocrine Abstracts 81, EP880): oxygen uptake per kilogram of fat-free mass 47.3 against 53.3 in cisgender women in the review's table (47.7 against 53.3 in the abstract), and grip strength per kilogram of fat-free mass 0.6 against 0.7 in the abstract, neither difference significant. doi.org endocrine-abstracts.org
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International Olympic Committee (2021). IOC Framework on Fairness, Inclusion and Non-Discrimination on the Basis of Gender Identity and Sex Variations, November 2021, as quoted and described in Pigozzi F. et al. (2022), Joint position statement of the International Federation of Sports Medicine (FIMS) and European Federation of Sports Medicine Associations (EFSMA) on the IOC framework, BMJ Open Sport & Exercise Medicine 8(1), e001273. Source for the principle of no presumption of advantage, the framework superseding the 2015 consensus, eligibility being left to the federations, and World Athletics' earlier 12-month testosterone rule. europepmc.org
FINA (now World Aquatics) (2022). Policy on eligibility for the men's and women's competition categories, adopted by its Bureau on 18 June and ratified by its Congress on 19 June 2022, in force 20 June 2022. Source for the Tanner stage 2 or age 12 rule, the open category to be studied, and its science group's finding of persistent legacy effects. resources.fina.org
World Aquatics (2023). Update on the Open Category competitions at the World Aquatics Swimming World Cup, Berlin 2023, 3 October 2023. Source for no entries in the pilot open category. worldaquatics.com
World Athletics (2023). World Athletics Council decides on Russia, Belarus and female eligibility, press release, 23 March 2023. Source for the exclusion from female world ranking competition from 31 March 2023, the council's reasons, and Sebastian Coe as World Athletics' president. Sebastian Coe's words at the press conference are as Attitude reported them, 24 March 2023; Sports Illustrated, 23 March 2023, reported his words on the overarching principle. worldathletics.org attitude.co.uk si.com
Union Cycliste Internationale (UCI) (2023). The UCI adapts its rules on the participation of transgender athletes in international competitions, July 2023. Source for the body's full name, the decision of 5 July, in force 17 July 2023, and its reasons. uci.org
NCAA (2025). NCAA announces transgender student-athlete participation policy change, 6 February 2025; and Executive Order 14201, Keeping Men Out of Women's Sports, 5 February 2025, Federal Register 90 FR 9279. Source for the NCAA's change and its date against the order's. ncaa.org govinfo.gov
World Athletics (2025). World Athletics introduces SRY gene test for athletes wishing to compete in the female category, 30 July 2025. Source for the once-in-a-lifetime SRY test, in force from 1 September 2025. worldathletics.org
MedlinePlus Genetics (2022). SRY gene. U.S. National Library of Medicine, page last updated 28 September 2022. Source for the gene's full name, sex-determining region Y, its place on the Y chromosome, and boys and men typically having one X and one Y chromosome. medlineplus.gov
International Olympic Committee (2026). Policy on the Protection of the Female (Women's) Category in Olympic Sport, announced 26 March 2026 (IOC Newsroom). Its terms are as RTE (27 March 2026) and NPR (26 March 2026) reported them: one-time SRY gene screening for female events from the Los Angeles 2028 Games, exceptions for complete androgen insensitivity and other rare differences of sex development, and, in RTE's account, the turn away from the IOC's 2021 approach of leaving the rules to the federations. NPR is also the source for Laurel Hubbard as the only openly transgender woman known to have competed at an Olympics. newsroom.olympics.com rte.ie npr.org
NPR (2024). The president of the NCAA calls for a ban on 'prop bets' in college sports, 17 December 2024. Source for Charlie Baker's testimony to the Senate Judiciary Committee: fewer than 10 transgender athletes among a little more than half a million. npr.org
European Court of Human Rights (2025). Grand Chamber judgment Semenya v. Switzerland, press release, 10 July 2025. Source for Caster Semenya's case concerning World Athletics' regulations for athletes with differences of sex development. hudoc.echr.coe.int
Note on the evidence base. Most studies in this literature are small, and most longitudinal physiology comes from clinical populations rather than athletes. The reviews draw on overlapping primary studies, so agreement between them is not independent confirmation.
Cite this article
TruthBased.org. “Do Trans Women Retain an Athletic Advantage?” Updated November 2026. https://www.truthbased.org/do-trans-women-retain-an-athletic-advantage