Longevity & Aging · Metabolic & Cardiometabolic
testosterone therapy increases muscle mass and strength
In plain terms: Does testosterone therapy build muscle?
Strong support Longevity & Aging 💰 Industry COI noted
Part of: 💊 Testosterone therapy (TRT)
RefutedContestedStrong support
consensus score 0.79
Yes — in men who genuinely have low testosterone, it reliably increases muscle mass and strength, and the effect is dose-dependent (one of TRT's most consistent benefits). Two caveats: injections work better than gels, and more muscle doesn't automatically mean better everyday physical function, especially in older men.
📅 Last reviewed: 2026-07-14 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
MechanismIn-vitroAnimalObservationalRCTMeta-analysis
How the studies fall
12 support 0 contradict 0 tested null 2 mixed · 14 sources, 12 independent groups
What the evidence shows
In men with low testosterone, testosterone therapy reliably increases lean (fat-free) muscle mass and strength — this is one of TRT's best-established effects. Multiple meta-analyses and classic dose-response trials show clear, dose-dependent gains (often 1.5-3 kg of lean mass, more at higher doses).
The evidence (18)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Neto WK, Gama EF, Rocha LY, Ramos CC, Taets W, Scapini KB, Ferreira JB, Rodrigues B, Caperuto É 2015 · Age (Dordr) | meta-analysis | supports | low | Meta-analysis of RCTs in men >60y with total T <=550 ng/dl: 11 studies included but only 8 pooled ('3 studies were not included in the meta-analysis'). Pooled lean-mass effect estimate 3.59 kg [2.38-4.81], but heterogeneity I2=98% and the component estimates do not overlap (1.65 kg [1.61-1.69] to 6.20 kg [5.22-7.18]), so the pooled figure summarises disagreeing trials rather than a stable effect. Bears on the muscle half of this claim only: the authors' stated outcomes were 'gains in weight, lean mass tissue and fat mass', with no strength endpoint. PubMed-only search closed 2013-10-04. |
| Isidori AM, Giannetta E, Greco EA, Gianfrilli D, Bonifacio V, Isidori A, Lenzi A, Fabbri A 2005 · Clin Endocrinol (Oxf) | meta-analysis | mixed | high | Random-effects meta-analysis of 29 RCTs in middle-aged and ageing men; 'Overall, 1,083 subjects were evaluated, 625 randomized to T, 427 to placebo and 31 to observation (control group). Weighted mean age was 64.5 years (range 49.9--77.6) and mean serum testosterone was 10.9 nmol/l (range 7.8--19).' SPLITS ON THE CLAIM'S COMPOUND OBJECT (muscle mass AND strength). MASS HALF SUPPORTED: 'an increase in fat free mass of 1.6 kg (CI: 0.6--2.6), corresponding to +2.7% (CI: 1.1--4.4) increase over baseline and (iii) no change in body weight' - and the endpoint is fat-free mass by the pooled trials' own methods, not muscle mass directly. STRENGTH HALF NULL: 'The effects of T on muscle strength were heterogeneous, showing a tendency towards improvement only at the leg/knee extension and handgrip of the dominant arm (pooled effect size=0.3 standard mean difference (SMD), CI: -0.0 to 0.6).' The interval includes zero and improvement appeared at only two of the tested sites, so this is a null on a directional claim, not the small positive effect the previous extract's 'strength effect modest/heterogeneous' implied. Same split shape as sibling row s41419182, ruled mixed for the reverse split. DENOMINATOR: 1,083 / 29 RCTs is the total across body-composition, strength, bone and lipid endpoints; the abstract never states how many trials fed the fat-free-mass or the strength pool, so both subset denominators are the available text does not say. METHOD: 'Guided by prespecified criteria, software-assisted data abstraction and quality assessed by two independent reviewers, 29 RCTs were found to be eligible', random-effects pooling with sensitivity and meta-regression - quality stays high; publication-bias testing is not mentioned in the abstract and is the paper does not say either way. Abstract-grade (not in the PMC open-access subset). |
| Hubska J, Jaszczuk P, Betlejewska J, Bylińska N, Bobrowicz M, Rak-Makowska B, Ambroziak U 2026 · Front Endocrinol (Lausanne) | observational | supports | low | Single-patient uncontrolled open-label case report (not an n-of-1 trial): woman with salt-wasting CAH and complete androgen suppression; severe myalgia resolved and she 'reported substantial improvement in muscle pain, strength' within 3 months, sustained across 10 years, with only a clinical impression of 'increased muscle tone' as objective support. No strength testing was performed, and lean mass was measured ONLY at baseline (lean tissue 40.8 kg, body fat 18.5%) - the 10-year DXA reports bone density and TBS, not body composition - so the muscle-mass half of the claim is untested by this paper. |
| Woodhouse LJ, Reisz-Porszasz S, Javanbakht M, Storer TW, Lee M, Zerounian H, Bhasin S 2003 · Am J Physiol Endocrinol Metab | RCT | supports | moderate | DUPLICATE POPULATION of the vault's parent trial trt-bhasin-2001 (PMID 11701431), which already votes on this claim: same laboratory, same protocol, same patients - 'Fifty-four young men were treated with a long-acting gonadotropin-releasing hormone (GnRH) agonist and one of five doses (25, 50, 125, 300, or 600 mg/wk) of testosterone enanthate (TE) for 20 wk', i.e. 54 of the 61 men Bhasin randomised. per CONVENTIONS 5; direction and design are recorded as supports/RCT only so the row reads correctly, not so it counts. WHAT THIS PAPER ITSELF REPORTS IS A PREDICTION MODEL, NOT AN EFFECT: the authors 'used univariate and multivariate analysis to identify the subset of baseline measures that best explained the variability in anabolic response to testosterone supplementation', and every output is variance explained - 'The three-variable model of TE dose, age, and baseline prostate-specific antigen (PSA) level explained 67% of the variance in change in whole body FFM', 64% for appendicular FFM (TE dose, baseline PSA, leg press strength) and 66% for thigh muscle volume (TE dose, log LH/T ratio, age). NO CHANGE MAGNITUDE, per-arm figure or P value for any endpoint appears anywhere in this abstract; the prior extract's 'muscle volume rose dose-dependently' was imported from the parent trial, not measured here. The conclusion is a statement about predictability - 'the anabolic response of healthy, young men to exogenous testosterone administration can largely be predicted by the testosterone dose.' ENDPOINTS: 'Anabolic response was defined as a change in whole body fat-free mass (FFM) by dual-energy X-ray absorptiometry (DEXA), appendicular FFM (by DEXA), and thigh muscle volume (by magnetic resonance imaging)'. ONLY THE MUSCLE HALF OF THE CLAIM'S OBJECT IS MEASURED: strength is not an outcome here - leg press strength enters only as a BASELINE PREDICTOR in the appendicular-FFM model. NO UNTREATED COMPARATOR: every arm received testosterone, so any increase rests on within-arm change plus the dose gradient. Internal validation only - 'The models were further validated by using Ridge analysis and cross-validation in data subsets', and two of the three models did not survive it: 'Only the model using testosterone dose, age, and PSA was a consistent predictor of change in FFM in subset analyses.' Held as a candidate, not in the stance: 'The length of CAG tract was only a weak predictor of change in thigh muscle volume and lean body mass.' Abstract-grade (PubMed efetch); randomisation method, blinding, allocation concealment and the 61-to-54 attrition are the available text does not say. |
| Kolla B, Kalra P 2025 · Indian J Med Res | observational | supports | low | Single-arm prospective cohort with no control group; 21 of 22 transmen analysed at 12 months on testosterone enanthate 150 mg (serum T 524.8 ng/dL). Muscle strength rose at 10 of 11 dynamometer sites (P<0.001; shoulder abduction right P=0.144, ns). Muscle mass rose in both bioimpedance modes but reached significance in trans mode only (26.17 to 28.04 kg, +7.15%, P=0.001), not in cis mode (26.27 to 27.03 kg, P=0.205). Authors name BIA-rather-than-DXA and operator-dependent strength testing as limitations, and every participant was also advised a standard exercise regimen. |
| Snyder PJ, Bhasin S, Cunningham GR, Matsumoto AM, Stephens-Shields AJ, Cauley JA, Gill TM, Barrett-Connor E, Swerdloff RS, Wang C, Ensrud KE, Lewis CE, Farrar JT, Cella D, Rosen RC, Pahor M, Crandall JP, Molitch ME, Cifelli D, Dougar D, Fluharty L, Resnick SM, Storer TW, Anton S, Basaria S, Diem SJ, Hou X, Mohler ER, Parsons JK, Wenger NK, Zeldow B, Landis JR, Ellenberg SS, Testosterone Trials Investigators 2016 · N Engl J Med | RCT | mixed | high | OFF-SCOPE ON THIS CLAIM'S OBJECT (muscle mass AND strength): the Testosterone Trials report measured neither. Its complete prespecified outcome set is sexual (PDQ-Q4 activity, DISF-M-II desire, IIEF erectile function), physical FUNCTION - 'The primary outcome of the Physical Function Trial was the percentage of men who increased the distance walked in the 6-minute walk test by at least 50 m', with the PF-10 self-report scale as a secondary - and vitality/mood (FACIT-Fatigue, SF-36 vitality, PANAS, PHQ-9). No DXA, lean-mass or dynamometer measure appears anywhere in the three trials. The authors separate the two concepts themselves: 'Although testosterone treatment consistently increased muscle mass and decreased fat mass, effects on physical performance, sexual function, and energy have been inconsistent' - muscle mass is their premise, physical performance is what they tested. Sibling precedent is explicit: trt-parahiba-2020 holds a pooled null Physical Performance Test result on this same claim 'off-object and held as a candidate only'. HELD AS A CANDIDATE INSTEAD (claim: testosterone therapy improves physical function in older men): the prespecified primary was NULL - 'Among men enrolled in the Physical Function Trial, there were no significant differences ... in the percentage of men whose 6-minute walking distance increased by at least 50 m (primary outcome) (odds ratio, 1.42; P = 0.20)', walking distance +4.09 m (95% CI -3.00 to 11.18, P=0.28), n=191 vs 196 - while the pooled all-participants analysis was positive (20.5% vs 12.6%, OR 1.76, P=0.003) and is labelled by the paper itself: 'The outcomes for all Testosterone Trials participants are exploratory outcomes.' The previous extract cited that exploratory pooled result without the label, and admitted in its own words that 'strength not a primary outcome' - it was not an outcome at all. |
| Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, Chen X, Yarasheski KE, Magliano L, Dzekov C, Dzekov J, Bross R, Phillips J, Sinha-Hikim I, Shen R, Storer TW 2001 · Am J Physiol Endocrinol Metab | RCT | supports | moderate | Randomised five-arm dose-response trial in 61 HEALTHY EUGONADAL men aged 18-35 - not hypogonadal patients on therapy - made experimentally androgen-deficient: '61 eugonadal men, 18-35 yr, were randomized to one of five groups to receive monthly injections of a long-acting gonadotropin-releasing hormone (GnRH) agonist, to suppress endogenous testosterone secretion, and weekly injections of 25, 50, 125, 300, or 600 mg of testosterone enanthate for 20 wk.' Roughly 12 men per arm (per-arm n not stated); EVERY arm received testosterone, so there is no untreated comparator and the increase is read from within-arm change plus the dose gradient. 'Energy and protein intakes were standardized.' DENOMINATOR OF THE HEADLINE NUMBER: +7.9 kg is the 600-mg/wk arm alone at a markedly supraphysiologic exposure, not a therapeutic dose - 'The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively.' THE AUTHORS' CONDITION IS MOST OF THE FINDING: 'Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly (change +3.4, 5.2, and 7.9 kg, respectively)' - the two lowest arms, at near-replacement concentrations of 253 and 306 ng/dl, showed no gain, so the effect begins above replacement dosing. Gradient is strong: 'The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log testosterone concentrations (r = 0.73, P = 0.0001).' STRENGTH IS CORRELATIONAL, NOT A REPORTED GAIN: 'Changes in leg press strength, leg power, thigh and quadriceps muscle volumes, hemoglobin, and IGF-I were positively correlated with testosterone concentrations' - no strength effect size, per-arm figure or P value appears in the abstract. Off-object and held as candidates only: HDL cholesterol and fat mass fell with dose, hemoglobin and IGF-I rose, and 'Sexual function, visual-spatial cognition and mood, and PSA levels did not change significantly at any dose.' Abstract-grade (not in the PMC open-access subset); blinding, allocation concealment and attrition are the available text does not say. |
| Traish AM 2016 · Am J Physiol Regul Integr Comp Physiol | mechanism | supports | low | ZERO-WEIGHT: single-author narrative review, not a primary observation — the paper names itself one twice ('As summarized in this review, a thorough and critical analysis of these studies showed that the risks purported are unsubstantiated and such studies lacked credible scientific and clinical evidence'; 'In this review, the benefits of T therapy in adult men with TD and the lack of credible evidence suggesting that T therapy is linked to increased CV risks are discussed'). It collects no data and re-passes the same trial and meta-analytic literature that seven meta-analysis rows on this claim already carry, so counting it is a double count — same ruling as the sibling umbrella row s42235305. DIRECTION IS RIGHT BUT UNQUANTIFIED AND HALF-SCOPED: 'A wealth of recent studies demonstrated that T therapy in men with TD is associated with increased lean body mass, reduced fat mass and waist circumference, improvement in glycemic control, and reduced obesity.' NO DENOMINATOR EXISTS: the available text names no constituent-study count, no participant total, no effect size and no interval for any endpoint. ENDPOINT COVERS ONE HALF OF THE OBJECT: lean body mass only — the word strength appears nowhere in the available text, so the review is silent on the strength half of 'muscle mass and strength'. The previous extract's 'consistently increases ... across trials' hardened the paper's 'is associated with' and added a consistency the paper never claimed. Framing is advocacy, not synthesis: 'It should be noted that the literature is replete with studies demonstrating beneficial effects of T therapy on CV and overall health' — quality stays low. GRADE FLAG for cultivar: stored as 'mechanism', but the paper describes no mechanism; zero-weight either way. Abstract-grade (NCBI efetch); search strategy, eligibility criteria and bias assessment are the available text does not say. |
| Ceolin C, Savino S, Gregorio C, Beraldo G, Dall'Agnol M, Termini G, Vetrano DL, Scala A, Ferlin A, Sergi G, Garolla A, De Rui M 2025 · Endocr Pract | observational | mixed | moderate | Prospective 1-year single-arm cohort, 107 trans/gender-diverse adults assigned female at birth starting testosterone GAHT, analysed only within 4 age bands (per-band n not reported): handgrip strength rose in all bands but significantly only in the youngest two (+4.35 kg at 25-29y, P=.001; +2.14 kg at 20-24y, P=.025), while DXA appendicular skeletal muscle mass index showed 'modest, non-significant increases in younger participants and plateaued or declined from age 30 onward'. Splits on the claim's object: strength yes, mass no. |
| Parahiba SM, Ribeiro ECT, Correa C, Bieger P, Perry IS, Souza GC 2020 · Exp Gerontol | meta-analysis | supports | moderate | Systematic review + random-effects meta-analysis of RCTs of testosterone supplementation vs placebo or lower dose in men aged >=40; 'Studies including individuals with age >= 40 years and which described the effect of T supplementation on sarcopenic components were found eligible (11 studies)', searches closed December 2019. DENOMINATORS ARE PER-OUTCOME SUBSETS OF THE 11, NOT THE 11. MASS HALF (8 studies): 'Regarding lean body mass (LBM), eight studies evaluated the effect of T supplementation on this outcome, of these, seven reported gains after the intervention period. Our meta-analysis showed a beneficial effect on LBM of 2.54 kg (95% CI, 1.27 to 3.80) (p < 0.001).' STRENGTH HALF, HANDGRIP (7 studies) IS A POOL-ONLY RESULT: 'seven included studies evaluated the handgrip strength (HGS) and just one reported gain after the intervention period, but the meta-analysis showed an increase for HGS of 1.58 kgf (95%CI, 0.17 to 3.0) (p = 0.03)' - six of the seven constituent trials individually null and the interval nearly touching zero. LEG STRENGTH (9 studies, five showing gains): 'In the meta-analysis, two out of three tests showed an effect on LS: T supplementation increase the leg press strength in 91.23 N (95%CI, 0.23 to 182.22) (p = 0.05) and leg extension in 144.10 N (95%CI, 44.21 to 244.00) (p < 0.01)' - leg press sits at the p=0.05 boundary with a CI lower bound of 0.23 N, and the third test was null. Both halves of the claim's compound object are therefore supported, the mass half solidly and the strength half fragilely. Off-object and held as a candidate only: physical performance was NULL - 'In physical performance, four studies evaluated this outcome, with three of them showing positive effects in this parameter. In the meta-analysis, only two studies that reported the same assessment test (Physical Performance Test) were included, but no effect of T supplementation on this parameter was found' - yet the authors' own conclusion asserts benefit 'in addition to physical performance', which their pooled result does not carry. Heterogeneity statistics and publication-bias testing are not reported in the abstract and are the available text does not say. INDEPENDENCE FLAG (recorded, not acted on): the umbrella row s42235305 quotes this paper's leg-press 91.23 N and leg-extension 144.10 N figures verbatim, confirming it re-passes this meta-analysis. Abstract-grade; full text Elsevier-paywalled and not in the PMC open-access subset. |
| Srinivas-Shankar U, Roberts SA, Connolly MJ, O'Connell MD, Adams JE, Oldham JA, Wu FC 2010 · J Clin Endocrinol Metab | RCT | supports | moderate | Randomised, double-blind, placebo-controlled, parallel-group, SINGLE-CENTRE trial (Manchester Andrology Research Unit): 'Two hundred seventy-four participants were randomized to transdermal T (50 mg/d) or placebo gel for 6 months', in 'community-dwelling intermediate-frail and frail elderly men at least 65 yr of age with a total T at or below 12 nmol/liter or free T at or below 250 pmol/liter'. THE TWO HALVES OF THE CLAIM'S COMPOUND OBJECT ARE REPORTED ON DIFFERENT FOOTINGS. STRENGTH IS BETWEEN-GROUP AND ADJUSTED: 'Isometric knee extension peak torque improved in the T group (vs. placebo at 6 months), adjusted difference was 8.6 (95% confidence interval, 1.3-16.0; P = 0.02) Newton-meters' - one muscle group, isometric, with the interval's lower bound at 1.3 Nm, so real but imprecise. MASS IS WITHIN-GROUP ONLY: 'Lean body mass increased and fat mass decreased significantly in the T group by 1.08 +/- 1.8 and 0.9 +/- 1.6 kg, respectively' - the abstract reports NO placebo-adjusted between-group difference for body composition and the change SD (1.8 kg) exceeds the mean change, so the previous extract's 'vs placebo' did not apply to the mass half. Note the route: this is TRANSDERMAL testosterone, the route sibling trt-skinner-2018 found produced no pooled lower-extremity strength gain. Off-object and held as candidates only: physical function improved in a subgroup only ('Physical function improved among older and frailer men', no effect size or denominator given), and 'Somatic and sexual symptom scores decreased with T treatment; adjusted difference was -1.2 (-2.4 to -0.04) and -1.3 (-2.5 to -0.2), respectively'. The authors hedge their own conclusion: T 'may prevent age-associated loss of lower limb muscle strength ... Further investigations are warranted to extend these results.' INDEPENDENCE FLAG (recorded, not acted on): this 2010 n=274 double-blind TRT-vs-placebo RCT falls inside the stated eligibility of the parahiba-2020, skinner-2018 and guo-2015 meta-analysis rows on this same claim, so its participants likely already vote through them; the abstracts list no constituent trials, so inclusion is the available text does not say. Abstract-grade (NCBI efetch; not in the PMC open-access subset) - randomisation method, allocation concealment, attrition and bias testing are the available text does not say. |
| Guo C, Gu W, Liu M, Peng BO, Yao X, Yang B, Zheng J 2016 · Exp Ther Med | meta-analysis | supports | moderate | Lean-body-mass pool = 5 of the 16 RCTs, 985 participants (496 treated / 489 control): MD +1.22 kg (95% CI 0.33 to 2.11, P=0.007). Significant in both duration subgroups (short-term 1.04; long-term 3.13) but in neither route alone (injection 1.7, P=0.06; transdermal 0.65, P=0.30). STRENGTH was not an endpoint - body composition only - so this bears on the mass half of the claim's object, not the strength half. |
| Junjie W, Dongsheng H, Lei S, Hongzhuo L, Changying S 2019 · Curr Pharm Des | meta-analysis | supports | low | Meta-analysis of 7 RCTs, 800 older men with low serum testosterone: 'T therapy increased prostate size, lean mass, sex hormone levels'. MASS ONLY — strength was not an endpoint of this paper. Its stated primary outcomes were 'the change in BMD, bone turnover markers, prostate symptoms, body composition, metabolic and endocrine system markers'; no muscle-strength or physical-function measure appears in the available text. Supports only the muscle-mass half of this claim's compound object. Two caveats: the increase is unquantified (no pooled estimate or CI in the abstract, full text paywalled), and the same abstract also reports 'no statistical effect on ... body composition', so lean mass rose without a net composition change. |
| López Hilario PP, Gabiati Niedo VR, Khan KS, Cano-Ibáñez N 2026 · Semergen | meta-analysis | supports | moderate | Umbrella review (units are syntheses, not primary studies): 'we conducted an umbrella review of systematic reviews (SRs) and meta-analyses of randomized clinical trials (RCTs) involving adults aged >=60 years receiving androgen therapy'. 'There were 11 eligible SRs, comprising 121 unique RCTs, with 20,846 male participants, none were women (of whom 8447 received testosterone therapy).' DENOMINATORS ARE SUBSETS: lean body mass comes from a 5-SR subset — 'Lean body mass changes in response to testosterone reported in 5 SRs of moderate to high quality ranged from 1.6kg (95% CI 0.6-2.6; I2=0.0%) to 3.59kg (95% CI 2.38-4.81; I2=98%)' — and strength from a separate 6-SR subset — 'Muscle strength changes in response to testosterone reported in 6 SRs of moderate to low quality showed maximal lower-limb effect in leg press (91.23 Newtons; 95% CI 0.23-182.22; I2=62%), and leg extension (144.10 Newtons; 95% CI 44.21-244.00; I2=0%)'. Neither figure carries the 20,846/8,447 denominator. Authors' own quality appraisal: 'Methodological quality was rated in 3 SRs as high, in 5 SRs as moderate, and in 3 SRs as low or critically low. The overlap was moderate (CCA=9.92%).' Direction is right — 'Testosterone therapy improved lean muscle mass and strength without adverse effect in older men' — but zero-weighted as an overview of reviews: seven meta-analyses already vote on this claim and are likely among the 11 re-passed here. Off-object and held as candidates only: 'There was no effect demonstrated on major cardiovascular events or all-cause mortality.' |
| Skinner JW, Otzel DM, Bowser A, Nargi D, Agarwal S, Peterson MD, Zou B, Borst SE, Yarrow JF 2018 · J Cachexia Sarcopenia Muscle | meta-analysis | supports | moderate | Meta-analysis of 41 double-blind placebo-controlled RCTs of TRT vs placebo in men with mean age >=45 (34 analysed; 15 intramuscular, 18 transdermal). THE TWO HEADLINE NUMBERS HAVE DIFFERENT DENOMINATORS: fat-free mass comes from 31 RCTs / 34 ESs (n=1213 TRT, 1168 placebo), ES 1.20 (95% CI 0.91-1.49), a 3.4% increase; total-body strength comes from a separate 17-RCT set / 100 ESs (n=2572 TRT, 2523 placebo), ES 0.90 (0.67-1.14), a 6.1% increase. ROUTE IS MOST OF THE FINDING: per cent improvements were 3-5x greater for intramuscular (FFM +5.7%, ES 1.49; total-body strength +11.2%, ES 1.39) than transdermal (FFM +1.7%, ES 0.98; strength +2.1%, ES 0.55), and transdermal produced NO lower-extremity strength gain, ES 0.26 (-0.19, 0.70), P=0.26. The route comparison is indirect - 'No RCT to date has directly compared muscular responses to different TRT administration routes' - each route is only vs its own placebo. QUALITY CAVEATS THE HEADLINE HIDES: the 100 strength ESs are non-independent (multiple measures per trial); the authors' own Mantel-Haenszel sensitivity analysis collapsing them to 35 widens the intervals and moves transdermal lower-extremity strength to 0.65 (-0.06, 1.36), P=0.07. Heterogeneity was 'significant (<0.05) in all scenarios considered'; no publication-bias (funnel/Egger) assessment is reported anywhere in the full text; and 7 of the 41 eligible RCTs were dropped because usable data could not be obtained. Subgroup limited to men >=60y was concordant (FFM ES 1.36, 4.2%). No conflicts of interest; VA-funded. |
| Arora V, Singh S, Benjamin J, Shasthry V, Singh SP, Kumar G, Sarin SK 2026 · Hepatol Int | RCT | supports | moderate | Single-centre randomised ADD-ON trial (Institute of Liver and Biliary Sciences, New Delhi), 127 men with cirrhosis and sarcopenia (median MELD 14; Child A 15.7%, B 64.7%, C 19.6%), 24 weeks: both arms received nutrition + structured exercise; the randomised variable was intramuscular testosterone undecanoate 1000 mg 'administered at 0, 6, 12, 16, 20, and 24 weeks (NExT group, n = 64)' vs 'only structured exercise and nutrition (NEx group, n = 63)'. ENDPOINT IS A RESPONDER PROPORTION, NOT A MEAN GAIN: the primary endpoint was 'a >= 10% increase in appendicular skeletal muscle index (ASMI) at 24 weeks, assessed by dual-energy X-ray absorptiometry (DEXA)', achieved 'in 41/64 (64.1%) patients in the NExT group compared with 16/63 (25.3%) in the NEx group (p < 0.001)' on intention-to-treat; the abstract reports NO mean or kg change in muscle mass, so this paper contributes no lean-mass magnitude. DENOMINATORS: 64.1%/25.3% are the ITT fractions over all 127 randomised; the concordant per-protocol figures '33/50 [66%] vs. 13/52 [25%]; p < 0.001' sit under the 102 completers (19.7% attrition). Strength: 'improvement in hand-grip strength (92% vs. 67.3%, p = 0.002)' - also a responder proportion, with no denominator stated in the abstract (cannot tell whether ITT or per-protocol). Population is cirrhosis-associated sarcopenia, not the claim's hypogonadal-men framing, and no placebo or blinding is described - which matters most for the effort-dependent secondary endpoints. Off-object and held as candidates only: liver frailty index, 6-min walk distance, serum ammonia, hospitalisation (18% vs 34.6%, p = 0.05). |
| Storer TW, Woodhouse L, Magliano L, Singh AB, Dzekov C, Dzekov J, Bhasin S 2008 · J Am Geriatr Soc | RCT | supports | moderate | Randomised, double-blind, graded-DOSE trial in 44 analysed HEALTHY EUGONADAL men aged 60-75 (of 60 randomised; completer counts 13/12/11/10 across the four retained arms) - not hypogonadal patients on therapy. Every arm received a monthly GnRH agonist to suppress endogenous testosterone plus weekly testosterone enanthate at 25, 50, 125 or 300 mg for 20 weeks: 'Subjects meeting eligibility criteria were randomly assigned using a block size of four to receive testosterone enanthate intramuscularly weekly in one of five dose regimens, 25, 50, 125, 300, or 600 mg/wk. All men received monthly injections of long-acting GnRH agonist during the treatment phase, starting on day 1.' THERE IS NO PLACEBO ARM, so the increase is read from within-arm change plus the dose gradient - note the paper's structured abstract calls itself 'placebo controlled', which its own Methods contradict. The 600 mg/wk arm was terminated by the DSMB 'because of the high frequency of erythrocytosis and leg edema' and excluded from all analyses. BOTH HALVES OF THE CLAIM'S OBJECT MOVE WITH DOSE: 'Significant T dose- and concentration-dependent increases were observed in SMM (P<0.001) and maximal strength (P=0.001), but not muscle fatigability.' DENOMINATORS OF THE HEADLINE NUMBERS ARE SINGLE ARMS, NOT THE 44: mass rose significantly from baseline only in the top two arms - 'Skeletal muscle mass increased significantly from baseline in both the 125 (8.5 +/- 4.0%) and 300 (11.1 +/- 4.3%) mg/wk dose groups' - and the strength figure is the top arm alone: 'Subjects receiving 300 mg T (nadir serum T=1784 ng/dL) demonstrated a significant increase in leg press strength (+19%) while no change was observed in subjects receiving 25 mg T (nadir serum T=176 ng/dL).' So the effect begins well above replacement dosing, and the +19% arm sat at a markedly supraphysiologic nadir. The two halves track each other: 'The changes in skeletal muscle mass and skeletal muscle mass index were significantly related to changes in leg press 1-RM strength, r = 0.64, P = 0.0001'. ENDPOINT: muscle mass is DEXA appendicular lean soft tissue pushed through a published ALST-to-MRI prediction equation, not a direct muscle measurement. Off-object and held as candidates only: leg power rose dose-dependently but only in the 300 mg arm (-2/+5/-2/+24%, ANOVA P=0.048, uncorrelated with serum T); fatigability was flat at every dose (P=0.407); and all six physical-function measures were null - 'changes in self-selected normal and fast walking speed over 6-m or 400-m, stair climbing power, and time for the TUG were not significantly related to T-dose, T-concentrations, or changes in muscle strength or power, or SMM' - with the authors conceding the trial 'may not have had sufficient power' for those endpoints in men who were 'unusually fit for their age'. INDEPENDENCE FLAG (recorded, not acted on): this is a secondary report - 'The study design and the main findings of this study have been published' (Bhasin 2005, PMID 15562020, not in the vault) - and its group_id 'storer' labels the same Bhasin/Woodhouse laboratory and the same GnRH-plus-graded-testosterone protocol as siblings trt-bhasin-2001 and trt-woodhouse-2003 under group_id 'bhasin-dose'. Full-text-grade (PMC2585153). |
| Mangolim AS, Brito LAR, Nunes-Nogueira VDS 2022 · Eur J Endocrinol | meta-analysis | supports | moderate | Systematic review + random-effects meta-analysis, 16 RCTs, men with obesity AND low testosterone levels (not obese men generally): 'With moderate certainty of the evidence ... TRT led to a 2-kg lean body mass gain'. DENOMINATOR: the 2-kg figure cannot be anchored to the 16-trial headline - the abstract states no trial count or participant number for the lean-body-mass pool, and that is the available text does not say (the only endpoint carrying its own denominator is cardiovascular events, 7 trials / 583 participants). ENDPOINT: lean body mass by the pooled trials' own methods; this paper measured NO strength or physical-function outcome, so the row bears on the mass half of the claim's object and is silent on the strength half. Moderate GRADE certainty is the authors' own rating. Abstract-grade; not in the PMC open-access subset. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
Opens a short form. You'll sign in with Google so submissions are tied to a real account — we don't display your identity, and we only accept a link we can verify (PubMed, DOI, ClinicalTrials.gov).
Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.