Running 10 hours a week for more than 120 km (75 miles) is extreme exercise, to be sure. Yet far from pushing the body beyond its limits, a new study suggests some professional athletes are adding years to their lives with such brutal routines.

The analysis includes public health data from the first 200 people to run a mile in under 4 minutes back in the 1950s, 60s, and 70s. According to a team of researchers from Canada and Australia, these professional runners lived, on average, almost 5 years longer than the general population.

The findings contradict the view that too much exercise has negative health effects in the long run. Pushing the human body to its max could actually be beneficial, at least for some.

While numerous epidemiological studies suggest that physically active individuals live longer than inactive individuals, it is as yet unclear whether exercising more than recommended is good or bad for health.

The lifestyles of high-intensity athletes who partake in marathons, endurance cycling, or triathlons could be putting undue stress on their hearts, some scientists suggest, putting them at greater risk of early death. But while strenuous exercise can certainly put sedentary individuals at risk of health issues, perhaps the outcomes are different for seasoned athletes.

In 2022, a Harvard study found that people who exercise more than recommended could lower their risk of death by 30 percent – 10 percent more than those who met activity guidelines.

Indeed, write University of Alberta cardiologist Stephen Foulkes and his colleagues, epidemiological studies of Tour de France cyclists, Olympic athletes, and rowers have shown increased lifespans compared to the general population.

Now, researchers have shown this pattern holds true for the fastest runners of a mile as well.

Athletes who can cross a mile marker in under 4 minutes are a unique population, known for pushing their respiratory, cardiovascular, metabolic, and musculoskeletal system to the max.

To achieve this level of speed, runners regularly partake in high-intensity bouts of physical activity throughout the week.

In 2018, cardiologists found that the first 20 runners to run a mile in under 4 minutes lived, on average, 12 years beyond general life expectancy.

The new study considers a larger cohort across three decades.

Interestingly, runners who completed a mile in under 4 minutes in the 1960s had greater life expectancy than runners who achieved the feat in successive decades.

"This may reflect improvements in life expectancy from the general population," the authors suggest, as well as the "management of several major communicable and non-communicable diseases."

In other words, not all the benefits in life expectancy seen in professional athletes may be due to their lifestyle alone. It's possible, for instance, that athletes possess favorable genes at higher rates compared to the general population. In the group of 200 mile-long runners, researchers counted 20 sets of siblings and several father and son duos.

"While we could not determine the cause of death for the majority of runners, studies reporting on Tour de France cyclists and cohorts of Olympians (that include middle to long distance runners) suggest the longevity effects are primarily mediated by decreased rates of cardiovascular and cancer-related mortality," write Foulkes and colleagues.

The outcome of their analysis, the team adds, "reiterates the benefits of exercise on the lifespan, even at the levels of training required for elite performance."

The study was published in the British Journal of Sports Medicine.