Before-and-after measurements in transgender women, study groups in Harper et al. (2021)

What this dataset measures

These are the two most-cited bodies of evidence on whether testosterone suppression removes the male athletic advantage: before-and-after clinical studies, gathered in the Harper et al. (2021) systematic review, and the only study of real fitness-test performance over time (Roberts et al. 2021). Using every adult 12-month study group in the review, rather than one study, avoids picking a favorable result.

Geography

United States, Europe

Unit of observation

Study group and measure; fitness measure and time band

Update cadence

As new before-and-after studies are published

Curator

FactHub Research Team

Curated data tables

Before-and-after measurements in transgender women, study groups in Harper et al. (2021)

One row per study group and measure, as listed in Tables 2-5 of the Harper et al. (2021) systematic review: testosterone, hemoglobin or hematocrit, muscle cross-sectional area, total lean body mass and strength. Testosterone values come from each study's before-and-after testosterone column. Rows marked included=no are adolescent or young-adult cohorts, or follow-ups that were not about 12 months; they are kept so readers can see what was left out.

Unit of observation: One study group and one measure

harper-12-month-study-groups.csv text/csv · 4.5 KB (4,574 bytes)

All 42 rows 15 columns Download the file

All 42 rows

measure	study	harperTable	group	n people	detail	baseline see units	followUp see units	units	months months	pctChangeReported %	testosteroneBefore nmol/L	testosteroneAfter nmol/L	included	exclusionReason
testosterone	Mueller et al (2011)	2	—	84	Serum testosterone	13.6	0.6	nmol/L	12	—	13.6	0.6	yes	—
testosterone	Wierckx et al (2014)	2	oral oestrogen	40	Serum testosterone	18.0	0.4	nmol/L	12	—	18.0	0.4	yes	—
testosterone	Wierckx et al (2014)	2	transdermal oestrogen	12	Serum testosterone	19.7	0.5	nmol/L	12	—	19.7	0.5	yes	—
testosterone	Gava et al (2016)	2	cyproterone acetate	20	Serum testosterone	16.3	0.7	nmol/L	12	—	16.3	0.7	yes	—
testosterone	Gava et al (2016)	2	leuprolide acetate	20	Serum testosterone	22.2	0.7	nmol/L	12	—	22.2	0.7	yes	—
testosterone	Auer et al (2016)	4	—	20	Serum testosterone	17.5	1.9	nmol/L	12	—	17.5	1.9	yes	—
testosterone	Haraldsen et al (2007)	2	—	12	Serum testosterone	16.8	8.6	nmol/L	12	—	16.8	8.6	yes	—
testosterone	Van Caenegem et al (2015)	3	—	49	Serum testosterone	19.0	0.5	nmol/L	12	—	19.0	0.5	yes	—
testosterone	Elbers et al (1999)	3	—	20	Serum testosterone	22.0	1.0	nmol/L	12	—	22.0	1.0	yes	—
testosterone	Wiik et al (2020)	4	—	11	Serum testosterone	18.0	0.5	nmol/L	12	—	18.0	0.5	yes	—
testosterone	Scharff et al (2019)	4	—	249	Serum testosterone	18.3	0.8	nmol/L	12	—	18.3	0.8	yes	—
testosterone	Gooren and Bunck (2004)	5	—	19	Serum testosterone	21.5	1.0	nmol/L	12	—	21.5	1.0	yes	—
testosterone	Tack et al (2018)	2	—	21	Serum testosterone	15.2	8.8	nmol/L	12-31	—	15.2	8.8	no	Adolescents; follow-up 12-31 months
testosterone	Olson-Kennedy et al (2018)	5	—	23	Serum testosterone	14.8	5.9	nmol/L	12	—	14.8	5.9	no	Youth cohort (adolescents and young adults)
hemoglobin	Wierckx et al (2014)	5	oral oestrogen	40	Hematocrit	45	42	%	12	-7.0	18.0	0.4	yes	—
hemoglobin	Wierckx et al (2014)	5	transdermal oestrogen	12	Hematocrit	45.5	42.2	%	12	-4.6	19.7	0.5	yes	—
hemoglobin	Auer et al (2016)	5	—	20	Hematocrit	45.2	42.7	%	12	-5.5	17.5	1.9	yes	—
hemoglobin	Gooren and Bunck (2004)	5	—	19	Hemoglobin	9.3	8.0	mmol/L	12	-14.0	21.5	1.0	yes	—
hemoglobin	Wiik et al (2020)	5	—	10	Hemoglobin	150.3	133.3	g/L	12	-11.7	18.0	0.5	yes	—
hemoglobin	Defreyne et al (2018)	5	—	239	Hematocrit	45.0	41.0	%	3	-8.9	17.4	0.7	no	Measured at 3 and 24 months; no 12-month value
hemoglobin	Olson-Kennedy et al (2018)	5	—	23	Hemoglobin	153	140	g/L	12	-8.3	14.8	5.9	no	Youth cohort (adolescents and young adults)
muscleArea	Elbers et al (1999)	3	thigh	20	Muscle cross-sectional area	307	278	cm2	12	-9.5	22.0	1.0	yes	—
muscleArea	Wiik et al (2020)	3	quadriceps	11	Muscle cross-sectional area	6193	5931	mm2	12	-4.2	18.0	0.5	yes	—
muscleArea	Van Caenegem et al (2015)	3	forearm	49	Muscle cross-sectional area	3999	3664	mm2	12	-8.6	19.0	0.5	yes	—
muscleArea	Van Caenegem et al (2015)	3	tibia (calf)	49	Muscle cross-sectional area	7742	7623	mm2	12	-1.5	19.0	0.5	yes	—
muscleArea	Tack et al (2018)	3	forearm	21	Muscle cross-sectional area	3275	3142	mm2	12-31	-4.1	15.2	8.8	no	Adolescents; follow-up 12-31 months
leanMass	Mueller et al (2011)	2	—	84	Total lean body mass	59.6	57.2	kg	12	-4.0	13.6	0.6	yes	—
leanMass	Wierckx et al (2014)	2	oral oestrogen	40	Total lean body mass	56.0	53	kg	12	-5.4	18.0	0.4	yes	—
leanMass	Wierckx et al (2014)	2	transdermal oestrogen	12	Total lean body mass	62.6	59.7	kg	12	-4.6	19.7	0.5	yes	—
leanMass	Gava et al (2016)	2	cyproterone acetate	20	Total lean body mass	51.7	49.9	kg	12	-3.5	16.3	0.7	yes	—
leanMass	Gava et al (2016)	2	leuprolide acetate	20	Total lean body mass	50.2	49.8	kg	12	-0.8	22.2	0.7	yes	—
leanMass	Klaver et al (2018)	2	—	179	Total lean body mass	57.2	55.5	kg	12	-3.0	—	—	yes	—
leanMass	Haraldsen et al (2007)	2	—	12	Total lean body mass	54.4	52.2	kg	12	-4.0	16.8	8.6	yes	—
leanMass	Van Caenegem et al (2015)	2	—	49	Total lean body mass	57.4	55.1	kg	12	—	19.0	0.5	yes	—
leanMass	Auer et al (2018)	2	—	45	Total lean body mass	59.5	57.5	kg	5-31	-3.4	17.5	1.9	no	Follow-up 5-31 months
leanMass	Tack et al (2018)	2	—	21	Total lean body mass	47.0	44.8	kg	12-31	-4.7	15.2	8.8	no	Adolescents; follow-up 12-31 months
strength	Van Caenegem et al (2015)	4	hand grip	49	Hand grip strength	42	39	kg	12	-7.1	19.0	0.5	yes	—
strength	Auer et al (2016)	4	hand grip	20	Hand grip strength	41.7	41.9	kg	12	0.5	17.5	1.9	yes	—
strength	Scharff et al (2019)	4	hand grip	249	Hand grip strength	41.8	40.0	kg	12	-4.3	18.3	0.8	yes	—
strength	Wiik et al (2020)	4	knee extension	11	Knee extension torque	239.7	242.6	N-m	12	1.2	18.0	0.5	yes	—
strength	Wiik et al (2020)	4	knee flexion	11	Knee flexion torque	99.5	101.5	N-m	12	2.0	18.0	0.5	yes	—
strength	Tack et al (2018)	4	hand grip	21	Hand grip strength	33.8	34.3	kg	12-31	1.5	15.2	8.8	no	Adolescents; follow-up 12-31 months

15 field definitions

Field	Type	Meaning	Units	Value type
measure	string	testosterone, hemoglobin (hemoglobin or hematocrit), muscleArea, leanMass or strength.	—	observed
study	string	First author and year, as cited by Harper et al.	—	observed
harperTable	integer	Table number in Harper et al. (2021) where the row appears.	—	observed
group	string	Sub-group or body region, where the study reported more than one.	—	observed
n	integer	Number of transgender women in the group.	people	observed
detail	string	What was measured.	—	observed
baseline	number	Mean (or median) before hormone treatment.	see units	observed
followUp	number	Mean (or median) at follow-up.	see units	observed
units	string	Units of baseline and followUp.	—	observed
months	string	Months of treatment at follow-up; a range where the study pooled follow-ups.	months	observed
pctChangeReported	number	Percentage change as printed by Harper et al.; blank for testosterone (not printed) and one lean-mass row whose value was not printed.	%	observed
testosteroneBefore	number	Group testosterone before treatment, from Harper et al.'s testosterone column.	nmol/L	observed
testosteroneAfter	number	Group testosterone at follow-up.	nmol/L	observed
included	string	yes if the row is an adult study group measured at about 12 months; no otherwise.	—	derived
exclusionReason	string	Why a row was left out of the medians.	—	derived

Supporting files

Source snapshots, manifests, quality reports, documentation, and other materials used to produce or review this release.

• analyses.json Derived table · application/json · 16.7 KB (17,090 bytes)

  Every saved-analysis result in this dataset, as computed by build.js.

• build.js Transformation manifest · text/javascript · 4.2 KB (4,317 bytes)

  Node.js script that computes every saved analysis from the two curated tables.

Sources

1. Harper J, O'Donnell E, Sorouri Khorashad B, McDermott H, Witcomb GL (British Journal of Sports Medicine) Systematic review, Tables 2-5: per-study changes in lean body mass, muscle cross-sectional area, strength and hemoglobin or hematocrit, with each study's testosterone before and after treatment, in transgender women on hormones. Free copy

   Retrieved November 5, 2026. CC BY 4.0. Open access under CC BY 4.0; FactHub republishes the extracted numbers with attribution.

   Reliability: Peer-reviewed study. Peer-reviewed systematic review of 24 studies of non-athletic transgender women, from Loughborough University and partners; no specific funding and no competing interests declared.

2. Roberts TA, Smalley J, Ahrendt D (British Journal of Sports Medicine) Table 4: U.S. Air Force fitness-test push-ups, sit-ups and 1.5-mile run times of 46 transgender women before and during hormone treatment, compared with the average Air Force woman and man under 30.

   Retrieved November 5, 2026. Copyright BMJ; numbers reported as facts. FactHub republishes the table's means, differences and confidence intervals as facts, with attribution; the article text is not redistributed.

   Reliability: Peer-reviewed study. Peer-reviewed study of U.S. Air Force medical and fitness records, 2004-2018, by military and academic pediatricians; no specific grant. Fitness tests measure endurance, not maximal strength, and the comparison is to an Air Force average, not matched controls.

3. Scharff M, Wiepjes CM, Klaver M, Schreiner T, T'Sjoen G, den Heijer M (Endocrine Connections) Cross-check of the largest 12-month study group: 249 transgender women in the European ENIGI cohort, grip strength 41.8 kg before and 40.0 kg after 1 year; median testosterone 17.9-18.5 nmol/L before and 0.4-0.8 nmol/L during treatment by clinic (Table 1). Free copy

   Retrieved November 5, 2026. CC BY 4.0. Open access; numbers republished with attribution.

   Reliability: Peer-reviewed study. Multicenter prospective clinical cohort in Amsterdam, Ghent and Oslo; authors declare no conflict of interest.

4. Wiik A, Lundberg TR, et al. (Journal of Clinical Endocrinology & Metabolism) Cross-check of the Wiik study group: thigh muscle volume fell 5% and quadriceps cross-sectional area 4% in 11 transgender women after 12 months, while strength was maintained.

   Retrieved November 5, 2026. Copyright Endocrine Society; numbers reported as facts. Numbers republished as facts with attribution.

   Reliability: Peer-reviewed study. Prospective study of 11 untrained transgender women at Karolinska Institutet, Stockholm; funded by Stockholm County Council and two foundations; no conflicts declared.

License: FactHub's selection, cleaning and combined tables are licensed under CC BY 4.0. Source data keeps the terms listed above (terms).

Limitations and reproducibility

Reproducible from public sources: Both curated tables are transcribed from published tables (Harper et al. 2021, Tables 2-5; Roberts et al. 2021, Table 4). build.js computes every saved analysis from them. The largest 12-month group (Scharff 2019) and the Wiik 2020 group were cross-checked against the original papers.

• Nearly all participants were adults, and none were competitive athletes. No before-and-after study has measured athletic performance in transgender girls.
• The 12-month medians count each study group once, regardless of size, and pool different muscles and strength tests.
• The Air Force comparison is to an average woman, not to matched women with the same training.
• Changes after 12 months are not charted; the review found too few studies to say whether losses continue.