Urolithin A for Muscle & Endurance: 70-Year-Olds to Elite Runners
Educational summary — not medical advice. This is not strength-training-substitute or athletic-performance-enhancement evidence for everyone; findings are population-specific. This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.
The honest answer
Walk the evidence from oldest and most sedentary to youngest and most trained, and a pattern holds up more consistently than any single "urolithin A works" claim: muscle endurance and fatigue resistance improve more reliably than raw maximal strength. Five trials, five different populations, five different patterns — some null on strength, some null on performance, some positive on endurance. Two had null primary endpoints, with the positive findings landing on secondary measures — named honestly below, before the secondary result.
Five populations, read in order
This is deliberately the widest population spread of any evidence pocket in this cluster — sedentary 70-year-olds, untrained overweight middle-aged adults, young resistance-trained lifters, elite altitude-training distance runners, and adolescent academy soccer players. Reading them in that order shows both where the signal holds and where it doesn't, rather than cherry-picking the strongest single result.
| Study | Population & design | Dose & duration | Result |
|---|---|---|---|
| Liu 2022 PMID 35050355 | RCT, n=66 (33/33), sedentary older adults 65-90y (75.8% female), University of Washington-led | 1,000 mg/day, 4 months | PRIMARY endpoints (6-minute walk distance; hand-muscle ATP production) NOT significant. SECONDARY: leg- and hand-muscle endurance (fatigue resistance) significantly improved at 2 and 4 months; CRP decreased. Partially Amazentis-funded/co-authored. |
| Singh 2022 PMID 35584623 | RCT, n=88 randomized/79 completed, untrained overweight adults 40-65y | 500 mg or 1,000 mg/day, 4 months | Hamstring strength +~12% at BOTH doses (p=0.027-0.029). Peak VO2 and 6-minute-walk distance significant only at 1,000mg. Plasma acylcarnitines and CRP decreased. Fully Amazentis-funded — the strongest positive trial in this pack. |
| Zhao 2024 PMID 39487653 | RCT, n=20, young (mean 24y) resistance-trained male athletes | 1,000 mg/day, 8 weeks | Maximal voluntary isometric contraction and repetitions-to-failure improved significantly (p=0.048, p=0.011). Bench press/squat 1RM NOT significant. CRP decreased. INDEPENDENTLY funded (Jiangsu Province grant, no COI) — the one non-Amazentis trial in this pack. |
| Whitfield 2025 PMID 40839339 | RCT, n=42 (22/20), highly-trained male distance runners, 4-week altitude camp | 1,000 mg/day, 4 weeks | PRIMARY 3000m time-trial performance NOT significantly different in either arm. SECONDARY: VO2max increase larger in the UA group; creatine kinase (muscle damage) significantly reduced post-race; lower perceived exertion. Amazentis-funded. |
| Monsalve Acevedo 2025 PMID 41245402 | Pilot RCT, n=20, adolescent academy soccer players (mean age 17.5y), single-blind | 1,000 mg/day, 6 weeks (below the manufacturer's own 8-week minimum) | Yo-Yo IRT1 endurance test improved ~239m more than placebo (95% CI 20-454, p=0.048, wide interval). Countermovement jump improved (p=0.020). Sprint speed not significant. Partially industry-adjacent funding (travel reimbursement only); primary grant unrelated. |
What holds up, and what doesn't
Read precisely, the strongest honest version of this claim is: across five small-to-modest trials in different populations, urolithin A supplementation was associated with improved muscle-endurance or fatigue-resistance measures more consistently than with improved maximal strength. In sedentary older adults (Liu 2022), the primary functional endpoints were null, but muscle-endurance fatigue resistance improved as a secondary finding. In untrained middle-aged adults (Singh 2022), strength improved at both tested doses, and endurance-adjacent measures (VO2, 6-minute walk) improved at the higher dose only. In young trained athletes (Zhao 2024), functional endurance improved but maximal strength (1RM) did not — a genuinely useful contrast showing the endurance signal doesn't automatically extend to raw strength even in a well-trained population. In elite distance runners (Whitfield 2025), the primary race-performance endpoint was null, with VO2max and muscle-damage-marker improvements landing as secondary results. In adolescent soccer players (Monsalve Acevedo 2025), a small, pilot-only endurance improvement showed a wide confidence interval.
Two of these five trials — Liu 2022 and Whitfield 2025 — had null primary endpoints, and both are read here with that null result named first, before the positive secondary findings. That ordering matters: skipping straight to "muscle endurance improved" in either trial overstates what was actually the trial's main, pre-registered question.
If you're taking it for muscle endurance
If you want to try urolithin A for this specific reason with realistic expectations, the evidence most consistently supports a modest fatigue-resistance/muscle-endurance effect rather than a maximal-strength or race-performance guarantee, and 1,000mg/day is the dose used in nearly every trial that measured an exercise or endurance outcome (see the dosage guide). None of these trials substitute for the intervention with by far the strongest evidence for muscle function and endurance at any age: structured exercise, particularly resistance and aerobic training combined. If mobility decline, unexplained muscle loss, or a competitive-performance goal is the underlying concern, that's worth discussing with a clinician or coach rather than addressing with a supplement alone — and worth reading the funding disclosure on the does-it-work page before weighting any single trial's result too heavily.
Frequently asked questions
Does urolithin A improve muscle endurance and exercise performance?
A muscle-endurance/fatigue-resistance signal shows up across 5 trials in different populations, more consistently than maximal-strength gains. Two trials had null primary endpoints with positive secondary findings.
Is urolithin A proven to build muscle or increase strength for everyone?
No. Results are population-specific — Singh 2022 found a real strength gain; Zhao 2024 found no 1RM change in trained athletes despite an endurance improvement in the same trial.
Why did two trials have null primary endpoints?
Liu 2022 (6-minute walk/ATP production) and Whitfield 2025 (3000m time trial) were both null on their primary outcome; the muscle-endurance/VO2max findings were secondary.
Is urolithin A a substitute for strength training?
No trial tested or supports that. All trials measured supplementation as an addition, not a replacement for exercise.
Related
- Urolithin A: what it is & the funding count
- Urolithin A dosage guide — the 500-1,000mg range in context
- Best urolithin A — the honest retail-landscape guide
- Does urolithin A work? — the honest, industry-funded read
Sources
- Liu S, D'Amico D, Shankland E, et al. "Effect of Urolithin A Supplementation on Muscle Endurance and Mitochondrial Health in Older Adults: A Randomized Clinical Trial." JAMA Netw Open. 2022. PMID: 35050355
- Singh A, D'Amico D, Andreux PA, et al. "Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults." Cell Rep Med. 2022. PMID: 35584623
- Zhao J, Zhu J, Yun H, et al. "Effects of urolithin A supplementation on muscle endurance, strength, and inflammatory biomarkers in trained young athletes." J Int Soc Sports Nutr. 2024. PMID: 39487653
- Whitfield J, et al. "Urolithin A Supplementation in Highly-Trained Distance Runners During an Altitude Training Camp." Sports Med. 2025. PMID: 40839339
- Monsalve Acevedo N, et al. "Urolithin A supplementation in adolescent academy soccer players: a pilot study." Front Nutr. 2025. PMID: 41245402