Urolithin A for Endurance Athletes

Reviewed by SOMA HEALTH's Medical Research Team

Endurance sport lives and dies on cellular energy. Whether you run marathons, ride centuries, or ski long tours, your ability to sustain effort for hours depends on how efficiently your muscle mitochondria convert oxygen and fuel into work. That is why urolithin A, a compound studied for its effect on mitochondrial quality, has become a topic of interest among endurance athletes.

This page from SOMA HEALTH lays out what urolithin A (UA) is, what human trials have actually shown about cellular energy and muscle endurance, and where the science is still early, so you can decide whether it fits your training with clear eyes.

The mitochondrial basis of endurance

Aerobic capacity is closely tied to the density and quality of mitochondria in your working muscle. Endurance training is the most potent natural driver of mitochondrial biogenesis, the manufacture of new mitochondria, and decades of exercise physiology confirm that trained endurance athletes carry substantially more mitochondrial content than sedentary people. More capable mitochondria mean more sustainable ATP production, better fat oxidation at submaximal intensities, and a higher ceiling for prolonged effort.

Yet a healthy mitochondrial pool is not just about building more. Cells also depend on a recycling process, mitophagy, that identifies and clears damaged mitochondria so they can be replaced. When mitophagy lags, worn units accumulate and the average efficiency of the pool declines. Urolithin A is studied because it appears to support this recycling step, which is why it is conceptually relevant to a sport that stresses the aerobic system day after day. Our page on mitochondrial health goes deeper on this system.

What urolithin A is and why supplementation is studied

UA is a gut postbiotic. You do not absorb it directly from food. It is produced when gut bacteria metabolize ellagitannins, plant compounds abundant in pomegranate, walnuts, and certain berries. The complication is that only some people host the microbes required to make useful amounts of UA. A large fraction of adults are thought to be poor converters, meaning that eating the parent foods does not reliably raise their UA levels. That variability is precisely why direct supplementation has been investigated in controlled trials. For the food angle, see foods high in urolithin A, and for the full picture, our urolithin A guide.

Human evidence, ordered from most established to newest

Proven in humans: safety and mitochondrial engagement

The first-in-human study, Andreux and colleagues (2019, Nature Metabolism), found UA to be safe and well tolerated in healthy older adults at doses up to 1,000 mg per day, and documented a shift in the expression of mitochondrial genes in muscle. For an endurance athlete, this is the groundwork: the compound reaches muscle, engages the pathways it is meant to, and did so with a reassuring tolerability profile at the doses tested.

Muscle endurance and strength: the functional trials

Two randomized human trials pushed toward function, and both are directly relevant here. Liu, D'Amico and colleagues (2022, JAMA Network Open) supplemented older adults for roughly four months and reported improvements in measures of muscle endurance, the fatigue resistance that endurance athletes prize. Singh and colleagues (2022, Cell Reports Medicine) studied middle-aged adults for four months using 500 mg and 1,000 mg arms and reported gains in muscle strength and aspects of exercise performance. The important caveat: participants were not competitive endurance athletes, and endpoints were laboratory measures rather than race performance. Still, muscle endurance is the exact quality long-distance sport depends on, which makes these the most pertinent results to date.

Newer human research

The literature has continued to grow. A 2024 randomized trial in the Journal of the International Society of Sports Nutrition examined eight weeks of UA in resistance-trained men. A 2025 randomized trial in Nature Aging reported that about 28 days of UA supported immune-cell mitochondrial health in midlife adults, relevant to the low-grade inflammation, sometimes called inflammaging, that accompanies heavy training loads. And a 2025 trial in distance runners has begun testing UA directly in an endurance population. These are encouraging additions, but each is a single trial, and they should be read as building evidence rather than final answers. For a fuller catalog, see our urolithin A clinical studies summary.

Preclinical research, clearly labeled as such

The foundational discoveries were preclinical. Ryu and colleagues (2016, Nature Medicine) showed that UA triggered mitophagy and extended lifespan in the worm C. elegans, and improved muscle function in rodents, the work that first put UA on the map for muscle and aging. Preclinical osteoarthritis models (D'Amico and colleagues, 2022, Aging Cell) have explored joint and cartilage effects, an interesting angle for high-mileage athletes, but it remains animal-model research and is not evidence that UA treats or protects joints in people. Early or preclinical exploration also touches skin, gut, brain, and heart. Treat all of this as hypothesis-generating, not as proof of benefit in human endurance athletes.

Honest limitations

A 2024 systematic review in Ageing Research Reviews concluded that the human evidence for UA is still emerging. That is the fair summary. No trial has demonstrated that UA lowers your marathon time, raises your lactate threshold, or improves your VO2 max, and claims to the contrary outrun the data. What the human evidence supports is more modest: good tolerability at studied doses, engagement of mitochondrial pathways, and improvements in laboratory measures of muscle strength and endurance in non-athlete groups. UA is at best a supporting input alongside the things that truly move endurance, structured training, adequate fueling, iron and nutrition status, and recovery.

A note on health: this page describes support for normal cellular energy processes; it is not medical advice and UA is not a treatment for any condition. Persistent fatigue, performance decline, breathlessness, or pain can have medical causes. If you are experiencing any of these, please see your doctor rather than reaching for a supplement.

Practical guidance for endurance athletes

Studied doses run 500 mg to 1,000 mg per day, with 1,000 mg as the top. In the trials that showed functional change, benefits emerged over months, so consistency through a training cycle makes more sense than dosing around a single event. UA is not a stimulant, so it carries none of caffeine's timing or dependency considerations; the logic is steady daily use during heavy aerobic volume. For related reading, see urolithin A for energy and, when you are ready to compare products, best urolithin A gummies.

Shop SOMA HEALTH Urolithin A Gummies

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This guide is educational and is not a substitute for advice from a qualified healthcare provider.