Does exercise really extend lifespan? It's complicated

Physical activity is seen as a way to extend the human lifespan, but the benefits of physical activity for longevity may not be as straightforward as previously thought.

That’s according to researchers from Finland’s University of Jyväskylä, who recently investigated the links between long-term leisure-time physical activity and mortality, as well as whether physical activity can mitigate the increased risk of mortality due to genetic predisposition to diseases. Moreover, they examined the relationship between physical activity and later biological aging.

The team’s study included 22,750 Finnish twins born before 1958 whose leisure-time physical activity was assessed in 1975, 1981 and 1990, with mortality follow-up until the end of 2020. Their results were published in the European Journal of Epidemiology, as well as Medicine & Science in Sports & Exercise.

Four distinct subgroups were identified from the data, which was based on leisure-time physical activity over the 15-year follow-up: sedentary, moderately active, active and highly active groups. When the differences in mortality between the groups were examined at the 30-year follow-up, it was found that the greatest benefit — a 7% lower risk of mortality — was achieved between the sedentary and moderately active groups. A higher level of physical activity brought no additional benefit.

When mortality was examined separately in the short and long term, a clear association was found in the short term: the higher the level of physical activity, the lower the mortality risk. In the long term, however, those who were highly active did not differ from those who were sedentary in terms of mortality.

According to Associate Professor Elina Sillanpää, “An underlying pre-disease state can limit physical activity and ultimately lead to death, not the lack of exercise itself. This can bias the association between physical activity and mortality in the short term.”

The researchers also investigated whether following the World Health Organization’s physical activity guidelines affects mortality and genetic disease risk. The guidelines suggest 150–300 minutes of moderate or 75–150 minutes of vigorous activity weekly. The study found that meeting these guidelines did not lower mortality risk or alter genetic disease risk. Even for twins who met the recommended levels of activity over a 15-year period, no statistically significant difference in mortality rates was found compared to their less active twin pair.

“The widely observed favourable association between physical activity and mortality are based on observational studies that are prone to bias from different sources,” noted postdoctoral researcher Laura Joensuu. “In our studies, we aimed to account for various sources of biases, and combined with the long follow-up period, we could not confirm that adhering to physical activity guidelines mitigates genetic cardiovascular disease risk or causally reduces mortality.”

For the subsample of twins, biological aging was determined from blood samples using epigenetic clocks. Epigenetic clocks allow a person’s biological aging rate to be estimated based on methyl groups that regulate gene expression and are linked to aging process.

“We found that the association between leisure-time physical activity and biological aging was U-shaped: biological aging was accelerated in those who exercised the least and the most,” Sillanpää said. Other lifestyles, such as smoking and alcohol consumption, largely explained the favourable associations of physical activity with biological aging.

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