Physical activity is thought to extend the human lifespan, but Finnish twin studies have found that the longevity benefits of physical activity may not be as clear-cut as previously thought. Researchers at the University of Jyväskylä in Finland investigated the links between long-term leisure-time physical activity and mortality, and whether physical activity can reduce the increased risk of death due to a genetic predisposition to disease. They also investigated the relationship between physical activity and later biological ageing. The study included 22,750 Finnish twins born before 1958 whose leisure-time physical activity was examined in 1975, 1981 and 1990. The mortality follow-up lasted until the end of 2020.
Moderate Activity Nrings Maximum Benefits for Longevity
Four distinct subgroups were identified from the data based on leisure-time physical activity during the 15-year follow-up period: sedentary, moderately active, active and highly active groups. When examining the differences in mortality between the groups after 30 years, it was found that the greatest benefit – a 7 percent lower risk of death – was achieved between the sedentary and moderately active groups.
A higher level of physical activity did not provide any additional benefit. In the separate study of mortality in the short and long term, a clear correlation was found in the short term: The higher the level of physical activity, the lower the risk of death. In the long term, however, those who were very active did not differ from those who were inactive in terms of mortality.
“An underlying pre-existing medical condition can limit physical activity and ultimately lead to death, not the lack of physical activity itself,” explains Associate Professor Elina Sillanpää from the Faculty of Sport and Health Sciences. This can distort the relationship between physical activity and mortality in the short term.
Adherence to Physical Activity Guidelines Does Not Guarantee a Lower Risk of Death
The researchers also investigated whether adherence to the World Health Organization’s physical activity guidelines affects mortality and the risk of genetic diseases. The guidelines recommend 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous activity per week. The study found that following these guidelines did not reduce the risk of death or alter the risk of genetic diseases. Even in twins who achieved the recommended levels of physical activity over a 15-year period, no statistically significant difference in mortality rates was found compared to their less active twin pair.
“The widespread observation of a positive association between physical activity and mortality is based on observational studies that are prone to bias from multiple sources,” says postdoctoral researcher Laura Joensuu from the Faculty of Sport and Health Sciences. In their studies, the researchers tried to account for different sources of bias, and in combination with the long follow-up period, they could not confirm that adherence to physical activity guidelines reduced the risk of genetic cardiovascular disease or causally reduced mortality.
Relationship Between Exercise and Biological Ageing is U-Shaped
For the subsample of twins, biological ageing was determined on the basis of blood samples using epigenetic clocks. Epigenetic clocks allow the estimation of a person’s biological ageing rate based on methyl groups that regulate gene expression and are associated with the ageing process. The researchers found that the relationship between leisure-time physical activity and biological ageing is U-shaped: biological ageing was accelerated in those who exercised the least and the most. Other lifestyles, such as smoking and alcohol consumption, largely explain the positive associations between physical activity and biological ageing.
Genetic data were available for 4,897 twins. The genetic susceptibility of twins to coronary heart disease and to systolic and diastolic blood pressure was assessed using new polygenic risk scores that sum up genome-wide susceptibility to morbidity. In addition, all-cause mortality and cardiovascular mortality were followed in 180 monozygotic twin pairs. The biological aging rate of 1,153 twins was assessed using a blood sample. The studies were conducted in collaboration with the Faculty of Sport and Health Sciences and the Methodology Center for Human Sciences at the University of Jyväskylä and the Finnish Institute of Molecular Medicine at the University of Helsinki.