Urolithin A for Endurance and VO2 Max: What the Research Shows
Key takeaways
- Endurance depends on how well your heart delivers oxygen and how well your muscle mitochondria use it, which is why researchers connect urolithin A to aerobic capacity.
- Urolithin A supports mitophagy, the process that clears worn-out mitochondria so healthier ones can take over.
- Human trials most consistently show improvements in muscle fatigue resistance and mitochondrial biomarkers, not faster race times.
- In a 2025 trial of trained distance runners, urolithin A did not improve time-trial performance or produce a significant VO2 max advantage over placebo.
- Benefits build gradually; the clearest results came after about four months of daily use.
The mitochondrial side of endurance
Every stride, pedal stroke and flight of stairs is powered by mitochondria, the structures inside your cells that convert oxygen and fuel into ATP. VO2 max reflects the most oxygen your body can take in and use during hard effort. It has two halves: delivery (your heart's output, blood volume and hemoglobin) and use (how many mitochondria your working muscles have and how well they function). In most healthy people, the delivery side sets the upper limit on VO2 max, while the muscle side has a big influence on how long you can sustain a hard pace before fatigue sets in.
That distinction matters for setting expectations. A compound that acts mainly on mitochondrial quality inside muscle would be expected to show up first in fatigue resistance and submaximal performance, and less in a peak VO2 number. Mitochondria also accumulate damage with age and heavy training, and the recycling process called mitophagy clears them. Animal and cell research shows this machinery tends to slow with age, one proposed reason endurance and recovery decline over time. For more on why VO2 max is such a strong marker of healthy aging, see our guide to VO2 max and aging.
Where urolithin A fits in
Urolithin A is a compound your gut microbiome can produce from ellagitannins found in foods like pomegranates, walnuts and certain berries. Many people carry gut bacteria that convert these precursors poorly or not at all, which is why standardized urolithin A is studied as a direct supplement.
Its headline mechanism is supporting mitophagy. In PRECLINICAL work in worms and rodents, urolithin A induced mitophagy and improved muscle function and exercise capacity (Ryu et al., Nature Medicine 2016). In HUMANS, the first-in-human study found the compound was safe and shifted muscle gene expression toward mitochondrial and cellular health in older adults (Andreux et al., Nature Metabolism 2019). In plain terms, it appears to help cells keep a cleaner, more efficient mitochondrial pool.
What the human endurance trials actually found
The mechanism is compelling, but human endurance outcomes have been a mix of promising signals and null results, and honest reporting has to include the null part.
In a four-month randomized trial in older adults, urolithin A at 1,000 mg a day did not significantly improve six-minute walk distance versus placebo, yet it did improve muscle fatigue resistance in hand and leg muscles and several plasma biomarkers of mitochondrial health (Liu et al., JAMA Network Open 2022). The classic aerobic-distance endpoint came back flat while a fatigue measure improved.
A four-month trial in middle-aged adults reported gains in leg muscle strength and some exercise-performance measures alongside improved mitochondrial biomarkers (Singh et al., Cell Reports Medicine 2022), with peak VO2 trending favorably but not as a clear standalone result. In 20 resistance-trained men, an eight-week trial of 1 g a day found more repetitions to failure and higher maximal isometric strength than placebo, while one-rep-max changes were not significant (JISSN 2024).
The most direct test of endurance performance is a 2025 randomized trial in 42 highly trained male distance runners at an altitude training camp. Four weeks of 1,000 mg a day did not improve 3,000 m time-trial performance. VO2 max rose in both groups, a little more with urolithin A, but the difference between groups was not statistically significant. Perceived exertion and a post-race muscle-damage marker (creatine kinase) were lower with urolithin A, and muscle samples showed more activity in mitochondrial pathways, but mitochondrial respiration itself did not change (Whitfield et al., Sports Medicine 2025). A 2024 systematic review of five human studies reached a similar overall picture: improvements in muscle strength and endurance, but no effect on cardiovascular outcomes or physical-function tests (Kuerec et al., Ageing Research Reviews 2024).
Endurance-related outcomes across human trials
| Population | Dose and duration | Endurance / aerobic outcome | Signal |
|---|---|---|---|
| Older adults | 1,000 mg, 4 months | Six-minute walk distance | No significant change |
| Older adults | 1,000 mg, 4 months | Muscle fatigue resistance + mitochondrial biomarkers | Improved |
| Middle-aged adults | 500 or 1,000 mg, 4 months | Strength, exercise performance, mitochondrial markers | Modest improvement |
| Resistance-trained men | 1,000 mg, 8 weeks | Repetitions to failure, isometric strength | Improved (1RM unchanged) |
| Trained distance runners | 1,000 mg, 4 weeks | 3,000 m time trial and VO2 max | No significant improvement (lower exertion and muscle-damage marker) |
The pattern: the more consistent results show up in muscle fatigue resistance, recovery markers and mitochondrial biomarkers, while peak aerobic performance has not clearly moved, especially in people who are already highly trained.
Endurance athletes vs. everyday stamina
These two audiences should read the evidence differently. If you are a highly trained endurance athlete chasing marginal gains, temper expectations: the human data point toward recovery and how hard efforts feel, not a measurable VO2 or race-time boost. Our page on urolithin A for runners covers the training-season angle, and our article on urolithin A and exercise recovery looks at the recovery data in more detail.
If you are an active ager or recreational exerciser whose stamina has quietly slipped, the picture is more encouraging. Fatigue resistance, the ability to keep a muscle working without giving out, is where the human trials have been most favorable, and it maps closely to how having more in the tank feels on a long walk, hike or bike ride.
What actually raises VO2 max
Training is the lever with by far the strongest evidence. A practical structure for most healthy adults:
- Mostly easy aerobic work. Two to four sessions a week at a conversational pace (often called zone 2) build mitochondrial density and capillaries in working muscle.
- One harder session a week. Intervals such as four rounds of four minutes hard with three minutes easy push the heart's delivery capacity, the main limit on VO2 max.
- Strength training twice a week. Stronger muscles make every submaximal effort feel easier and protect against injury.
- Recovery basics. Sleep, enough carbohydrate and protein, and iron status all affect how well you adapt. If fatigue is unusual for you, ask your doctor about checking iron and other causes.
If you have a heart condition, high blood pressure or symptoms such as chest pain or unusual breathlessness on exertion, talk to your doctor before starting high-intensity training.
Realistic expectations and timeframe
Urolithin A is not a stimulant and produces nothing you will feel on day one. It works upstream, on the quality of your mitochondrial pool, so any structure/function benefit accrues gradually. The clearest human results came after about four months of daily use, which is a reasonable window to evaluate your own response. Our VO2 max and endurance page summarizes dosing for active people.
Think of it as a foundation, not a pre-workout. It pairs with the things that independently drive endurance: consistent aerobic training, adequate protein and sleep. SOMA Urolithin A gummies deliver 1,000 mg a day, the dose used in most of the trials above, which makes it straightforward to run a consistent multi-month trial of your own.
Set the bar where the evidence sets it: better fatigue resistance and support for your cellular energy systems are realistic goals; a jump in VO2 max is not something the human trials have shown.
Frequently asked questions
Does urolithin A increase VO2 max?
The human evidence does not show a clear effect. In the most direct test, trained runners taking 1,000 mg a day for four weeks saw no significant VO2 max advantage over placebo and no time-trial improvement. Urolithin A more reliably supports muscle fatigue resistance and mitochondrial biomarkers than peak VO2 itself.
How is urolithin A connected to endurance at all?
Sustained effort depends heavily on mitochondrial function in your muscles. Urolithin A supports mitophagy, the process that recycles worn-out mitochondria, which supports the cellular energy production that endurance relies on.
Can't I just get it from pomegranates or walnuts?
Your gut bacteria have to convert precursors in those foods into urolithin A, and many people convert poorly or not at all. Standardized urolithin A delivers a consistent amount directly.
How long before I might notice anything?
The clearest muscle results came after about four months of daily use. Because urolithin A works on mitochondrial quality rather than acting as a stimulant, changes build gradually.
Should elite athletes bother with it?
Expectations should be modest. In highly trained runners the signals were lower perceived exertion and a lower muscle-damage marker, not a performance edge. It may fit a recovery-support routine, but it is not a proven way to lower race times.
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