Low Stamina in Your Sport? Support Endurance and Energy

Reviewed by SOMA HEALTH's Medical Research Team

It usually hits in the third set, the second half, or the last few points of a long rally: your legs stop responding, your first step loses its snap, and the shots or sprints that came easily early on start slipping away. For recreational and weekend athletes, running out of stamina before the game is over is one of the most common complaints, and it is rarely about not trying hard enough. It is about how much usable energy your muscles can keep producing over time.

This guide breaks down what stamina really is at the cellular level, why the mitochondria inside your muscles set the ceiling on it, and where a gut-derived compound called urolithin A fits in. We will be careful to separate what has actually been shown in people from what is still early or preclinical, because the honest picture is more useful than the hyped one.

What stamina actually is

Stamina, in physiological terms, is your capacity to sustain effort without your performance falling apart. Whether you play tennis, basketball, soccer, or pickup anything, holding your level through a long session depends on a steady supply of ATP, the molecule that fuels every muscle contraction. The bulk of that energy for sustained activity is produced aerobically inside mitochondria, the cellular structures often called the body's power plants. When your muscles have plenty of well-functioning mitochondria, they can keep generating energy at a given effort for longer before fatigue forces you to slow down.

Research in exercise physiology consistently ties endurance capacity to the density and function of mitochondria in skeletal muscle. Training increases both the number and quality of these power plants, along with the small capillaries that feed them oxygen, which is a big part of why a conditioned athlete can keep going while a less-trained one fades. Higher mitochondrial capacity is associated with better aerobic performance and the ability to sustain a harder pace before lactate builds up and forces you to back off. In short: more and healthier mitochondria generally translate to more stamina.

The reverse is also true. When some of your mitochondria become damaged or inefficient and are not cleared and replaced quickly enough, the muscle's energy production gets less reliable. That can contribute to the familiar mid-game fade. So stamina is not only about how many mitochondria you have, but about keeping the ones you have in good working order.

Mitophagy: your cellular maintenance crew

Cells have a built-in system for keeping their mitochondria healthy, called mitophagy. When a mitochondrion wears out or malfunctions, mitophagy identifies it, breaks it down, and recycles the parts, making room for fresher, better-performing replacements. It is essentially quality control for your energy machinery: instead of letting broken power plants clog the system, the cell clears them so the fleet stays efficient. We explain the process in plain terms in what is mitophagy, and put it in context in our overview of mitochondrial health.

Mitophagy runs continuously, but its efficiency can slip with age and can be taxed by demanding activity. That is exactly why urolithin A has drawn scientific interest, because it has been studied for its role in supporting this recycling step.

What urolithin A is (and why food alone may not deliver it)

Urolithin A is not a nutrient you consume directly. It is a postbiotic, produced by your gut bacteria. When you eat ellagitannins, the polyphenols in pomegranates, walnuts, and some berries, certain gut microbes convert them into urolithin A. The complication is that not everyone's microbiome does this well; studies indicate only a portion of people generate meaningful amounts from diet alone. That is one of the main reasons direct supplementation has been researched, since it provides a consistent, standardized dose no matter what your gut bacteria can or cannot do. For the dietary side, see foods high in urolithin A, and for the complete picture start with our urolithin A guide.

The scientific interest in urolithin A centers squarely on mitophagy. The idea under investigation is that by supporting the clearance of worn mitochondria, it may help muscle sustain a healthier mitochondrial pool over time. It is a reasonable and actively studied hypothesis, but how much weight it carries depends entirely on whether the evidence comes from animals or from humans, so let us look at that carefully.

The human evidence, strongest first

Safe and biologically active in people

The first-in-human trial, published by Andreux and colleagues in Nature Metabolism in 2019, showed two key things: urolithin A was safe and well tolerated at doses up to 1,000 mg per day, and it produced a measurable mitochondrial gene-expression signature in participants. That second point matters, because it means the compound was actually engaging the muscle's energy machinery rather than passing through with no effect. This study anchors everything that follows.

Trials in muscle and exercise performance

Several randomized human trials have examined muscle and performance outcomes. A 2022 study by Liu, D'Amico and colleagues (JAMA Network Open) found that older adults taking urolithin A for about four months improved on measures of muscle endurance. A 2022 trial by Singh and colleagues (Cell Reports Medicine) in middle-aged adults, using 500 mg and 1,000 mg daily arms over four months, reported gains in muscle strength and aspects of exercise performance. Moving into fitter populations, a 2024 randomized controlled trial in the Journal of the International Society of Sports Nutrition tested an eight-week protocol in resistance-trained men, and a 2025 trial looked at distance runners. Together these extend the research beyond older or sedentary groups toward the kind of active people who actually play sports.

For a recreational athlete, the fair reading is this: the human evidence most directly supports muscle endurance and strength, and the trained-population studies are encouraging but still limited in number. A 2024 systematic review in Ageing Research Reviews put it plainly, describing the human evidence for targeting aging processes with urolithin A as promising but still emerging. You can explore the individual trials in our urolithin A clinical studies summary, and see how it connects to training in urolithin A for energy.

A newer human signal: immune-cell mitochondria

A 2025 randomized controlled trial in Nature Aging (about a 28-day protocol) reported that urolithin A supported the mitochondrial health of immune cells in midlife adults, connected to the idea of inflammaging, the low-grade inflammation that tends to build with age. This broadens the story beyond muscle, but it is a single short study and should be read as an early, encouraging signal rather than a firm conclusion.

What remains preclinical

A lot of the enthusiasm around urolithin A comes from animal and cell studies, and it is essential to keep that separate from the human data. The influential 2016 study by Ryu and colleagues in Nature Medicine showed that urolithin A triggered mitophagy, extended lifespan in the roundworm C. elegans, and improved muscle function in rodents. Those results are mechanistically exciting but preclinical: findings in worms and rodents do not automatically carry over to a person's stamina on the court. Likewise, research on joints and cartilage (D'Amico and colleagues, Aging Cell, 2022) was done in osteoarthritis models, and topics such as skin, gut, brain, and heart are still at early or preclinical stages. Treat those as avenues researchers are exploring, not as proven benefits.

Practical guidance for weekend athletes

If you are thinking about adding urolithin A to your routine, keep a few grounded points in mind. The doses studied in humans run from 500 to 1,000 mg per day, with 1,000 mg at the top of the range; our urolithin A dosage page covers the details. Consistency beats timing: the human trials ran over weeks and months, so this is a daily background support, not a pre-game shot of energy. And nothing replaces the basics that build real stamina, which are regular conditioning, good fueling and hydration, sleep, and recovery between sessions. Urolithin A is best understood as support for the mitochondrial maintenance your training already demands, not a substitute for the training.

Set realistic expectations, too. Because urolithin A works gradually and depends on your existing fitness, do not expect an overnight change; our how long does urolithin A take to work page addresses the timeline. Finally, persistent or unexplained loss of stamina can have medical causes, from anemia to thyroid or heart conditions, so this content is educational and structure-function only. It is not a treatment for any condition. If your stamina drop is new, sudden, or out of step with your activity level, see your doctor rather than reaching for a supplement.

Explore SOMA HEALTH Urolithin A Gummies

For the full science and help choosing a product, see our urolithin A guide and our roundup of the best 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.