Pushing the Limits: How Extreme Running May Be Accelerating Your Body’s Ageing Process
For many runners, the mantra is simple: more miles equals better fitness. However, new research suggests that pushing the body to its absolute limits with extreme distances might not be the fountain of youth some believe. In fact, extensive research indicates that ultra-marathon running could be prematurely ageing your body, particularly your red blood cells.
Scientists at the University of Colorado Anschutz undertook a detailed analysis of blood samples from 23 dedicated athletes. These samples were collected immediately before and after they tackled either a demanding 40-kilometre (24-mile) marathon or an astonishingly gruelling 174-kilometre (108-mile) ultra-marathon.
The Impact on Red Blood Cells
Prior to the races, the athletes’ red blood cells, which are critical for transporting oxygen throughout the body, were in prime condition. They were noted for their flexibility, allowing them to navigate the body’s most minuscule blood vessels with ease.
However, the scene dramatically changed once they crossed the finish line. The post-race blood samples revealed a stark contrast: these vital cells had become more rigid. This increased stiffness impairs circulation, and the cells themselves displayed clear signs of inflammation and significant physical stress.
The findings were particularly pronounced for those who had undertaken the ultra-marathon. These athletes exhibited considerably more damage to their red blood cells compared to their marathon-running counterparts. Researchers observed that the deterioration of these cells closely mirrored the changes typically seen in an ageing body, where red blood cells naturally become less flexible and less efficient at carrying oxygen.
Dr Angelo D’Alessandro, a biologist and senior author of the study, explained the phenomenon. “Red blood cells are remarkably resilient, but they are also exquisitely sensitive to mechanical and oxidative stress,” he stated. “This study shows that extreme endurance exercise pushes red blood cells toward accelerated aging through mechanisms that mirror what we observe during blood storage.”
Dr D’Alessandro further elaborated on the implications: “Understanding these shared pathways gives us a unique opportunity to learn how to better protect blood cell function both in athletes and in transfusion medicine.”
The researchers theorise that the damage observed in red blood cells during these extreme running events is likely a consequence of inflammation and the fluctuating fluid pressures experienced as the cells circulate through the body during prolonged exertion.
It is important to note that the study’s authors are not advocating for people to abandon running. Instead, their findings highlight a specific consequence of participating in marathons and, more significantly, ultra-marathons: damage to red blood cells. A crucial limitation of the study is that blood samples were only taken immediately after the races. This means it remains unclear whether the observed damage is temporary or has long-term, permanent effects.
The research, published in the journal Blood Red Cells and Iron, involved testing thousands of biomarkers in the athletes’ blood to gain a comprehensive understanding of the physiological changes occurring.
The Races Under Scrutiny
To provide context for the extreme distances, the study involved participants from two notable endurance events:
- Martigny-Combe a Chamonix: Eleven participants completed this 40-kilometre (25-mile) route, which stretches from Switzerland into France. It’s an annual event held in August, attracting around 1,000 athletes.
- Ultra-Trail du Mont-Blanc (UTMB): Twelve participants tackled this epic 174-kilometre (108-mile) route, traversing France, Italy, and Switzerland. It is widely regarded as one of the world’s most “mythical and prestigious” running races, drawing approximately 10,000 runners each August.
For comparison, the well-known New York City and London marathons are approximately 42 kilometres (26.2 miles) long.
The study participants were, on average, 36 years old, comprising fourteen men and nine women. The exact volume of blood extracted from each participant was not specified.
Unanswered Questions and Future Directions
Dr Travis Nemkov, a biochemist who spearheaded the research, shared insights with Runners World. “At some point between marathon and ultramarathon distances, the damage really starts to take hold,” he observed. “We’ve observed this damage happening, but we don’t know how long it takes for the body to repair that damage, if that damage has a long-term impact and whether that impact is good or bad.”
Based on their current findings, the researchers caution that as the duration of a run increases, athletes can anticipate a greater loss of red blood cells and accumulate more damage to those that remain in circulation.
Understanding Red Blood Cell Ageing
In the natural ageing process, red blood cells gradually accumulate damage. This leads to increased rigidity, a decline in their ability to carry oxygen and essential nutrients to tissues, reduced oxygenation, and heightened inflammation. This also places increased cardiovascular stress on the body, as the heart must work harder to deliver the same amount of nutrients.
Furthermore, older red blood cells can begin to clump together, making the blood thicker and more viscous, which can impede blood flow and elevate the risk of serious events like strokes or heart attacks. Scientific consensus suggests these age-related changes in red blood cells typically begin to manifest in a person’s 50s and become more pronounced in their 60s.
The Broader Health Context
While doctors universally encourage physical activity, promoting running as an excellent method for enhancing cardiovascular health and overall fitness, there are growing concerns surrounding the extreme end of the running spectrum. Some medical professionals have voiced apprehension about ultra-marathon events, warning that participation might increase the risk of adverse health complications, including heart attacks.
Emerging research has also previously suggested a potential link between ultra-marathon running and a higher risk of colon cancer.
Globally, an estimated 50 million individuals engage in jogging or running annually in the United States alone, while a significant 130,000 people complete ultra-marathons each year. This vast number of participants underscores the importance of understanding the physiological toll these extreme events can take.
