Ultramarathons and Longevity: How Far Is Too Far?

Ultra-Trail du Mont-Blanc (UTMB) in Europe is 106 miles. Marathon des Sables (MDS) in the Moroccan Sahara desert is 155 miles. The Leadville race in the U.S. is 100 miles. These are just a few ultramarathons that running enthusiasts participate in.

Most people don’t even think about running one, but if the passion arises, it never disappears. The same thing happened to one of the best Ultra Runners, Tom Evans, who got involved in running after a bet with friends. Now, he is a champion of UTMB and finished MDS in the top three.

However, such a challenge carries its own consequences, as research suggests it may accelerate red blood cell aging. In this article, we’ll look at what studies say about how ultramarathons affect longevity and whether marathons or shorter races might be better options.

New findings on ultramarathons

In 2019, a study showed that ultramarathon runners experience a breakdown of normal red blood cells, which may lead to anemia or other health issues. However, the cause was not fully clear.

Some scientists revisited this topic in a new study, examining athletes who participated in the 25-mile Martigny-Combes à Chamonix race and the 106-mile UTMB. They collected blood samples before and after the runs and compared them.

The test results showed two types of damage: physical and molecular. Physical damage occurred when red blood cells became less flexible after a long race. This is crucial because red blood cells carry oxygen, and their flexibility is important for moving through narrow blood vessels.

Molecular damage was linked to inflammation and oxidative stress. This condition occurs when the body has low levels of antioxidants, leaving cells vulnerable to damage that can affect DNA and other vital components.

These patterns were observed even after a 25-mile run, but were more pronounced after a 106-mile race, suggesting longer distances may place more stress on red blood cells. Researchers note that more research is needed to understand how long it takes for the body to repair the damage and whether it has a long-term impact.

Ultramarathon impact on health

Dr. Shady Hassan, an Interventional Pain Management and Sports Medicine Physician and Founder of NefraHealth, asserts that ultramarathons are a performance pursuit rather than a requirement for good health.

He notes, “I see both sides of endurance sports. The incredible cardiovascular benefits and the long-term wear and tear on the musculoskeletal system.” He further adds that ultramarathons can boost mental resilience and aerobic capacity, however, “they increase the risk of overuse injuries, joint degeneration, and, in some cases, heart rhythm issues and heart muscle changes.”

A 2018 review of studies indicates that ultramarathon running may increase physiological stress across multiple systems, including metabolic, musculoskeletal, cardiovascular, renal, inflammatory, and immune functions.

For instance, approximately 50% of runners experience kidney injury with impaired renal function during a race. Additionally, extreme distance running frequently results in tendon and joint stress as well as overuse injuries.

The review notes that some of these changes may resolve with adequate rest in healthy athletes. However, it also warns that the amount of stress depends on the distance, intensity, environment, and the person. Repeated extreme stress may have longer-term effects.

How about marathons?

Dr. Jason Schroder, Medical Director at Craft Body Scan, says marathons and ultramarathons stress the body in different ways. “A marathon sits near the upper edge of what the cardiovascular system handles well with proper training,” he explains. Still, he notes that most runners bounce back within two to three weeks.

A 2025 review of 329 studies proves that. It found that marathon training may benefit multiple organ systems and reduce the risk of all-cause mortality. For example, it may decrease heart risks and improve lung, bone, and muscle function.

The review also noted that after a marathon, negative changes may occur in the renal, gastrointestinal, immune, musculoskeletal, and central nervous systems. However, they noticed that these changes usually normalized within a week.

It concluded that even though marathon running temporarily stresses the body, the long-term health benefits outweigh those stressors. Proper training, nutrition, and recovery are key to maximizing benefits and minimizing risks.

Ultimate running distance for longevity

Dr. Hassan thinks the issue is not the marathon but the imbalance: “In fact, endurance training benefits metabolic health and mitochondrial function, which improves markers associated with aging. What accelerates aging is chronic inflammation, sleep disruption, and overtraining without recovery.”

Some researchers have sought to understand which distance running is associated with better health, potentially leading to a longer life. One study compared 245 recreational runners across three race distances: 6.2 miles (10 km), half-marathon, and marathon/ultramarathon.

The results suggested that half-marathon runners scored highest in overall health, while 6.2-mile runners ranked second, with a score almost as high.

Another study used data from 4,458 adults in the U.S. National Health and Nutrition Examination Survey to see whether time spent running per week is associated with telomere length. They are related to cellular aging: the longer it is, the longer life it may predict.

Participants were grouped by self-reported weekly running or jogging time: less than 10 minutes, 10 to 74 minutes, or over 75 minutes. The study found that adults who ran or jogged at least 75 minutes a week tended to have longer telomeres, suggesting slower biological aging than the other groups.

Dr. Hassan concluded that sustainable fitness over the long term is far more powerful than short-term gains. “You want sustainability for 60–70 years, not just peak performance for 10 years.” Lastly, he recommends “steady zone 2 cardio, lifting twice weekly, and occasional higher-intensity intervals to preserve VO2 max.”

How to prepare for an ultramarathon?

While all running distances require preparation, ultramarathons demand an even higher level of commitment. According to Dr. Hassan, runners need more than just endurance — they need strength training, solid nutrition, recovery, and regular medical screenings.

Dr. Schroder agrees with that and adds his insights: “One of the most important things they can do early on is a baseline cardiac and pulmonary scan before they begin increasing training volume. From there, training should be a periodized structure with mandatory recovery blocks and not simply a continuous increase in mileage.”

Tom Evans is a good example of this approach. He says that for him, running doesn’t start on the track because everything he does has a purpose. He alternates between weeks focused on running (12–13 hours) and weeks dedicated to strength and conditioning. His training is also overseen by a professional medical team that offers guidance and regular testing to help him perform his best.

While running can be a hobby, ultramarathons and marathons are specialized sports that need dedication and expert support. However, if you want to increase your running distance or get ready for your first marathon, WellnessPulse has a detailed article on marathon preparation.

Final thoughts

Although undertaking new challenges such as ultramarathons may be appealing, it is important to consider the potential health consequences.

Professional athletes typically train under specialist supervision, whereas amateurs may lack such support. Gradually increasing running distance, beginning with shorter races and progressing to half-marathons and marathons, would be advised.

And for those seeking to enhance longevity, 75 minutes of running per week may be sufficient.