How Little Exercise is Needed to Obtain Significant Benefits to Life Expectancy?

People who undertake no moderate exercise suffer about as much as the heavily overweight, or smokers, when it comes to diminished life expectancy - though there is always the question of direction of causation in these correlations. Past studies have suggested that even a little regular exercise improves matters considerably. But how little? The human dose-response curve for exercise is being mapped out, slowly, through large epidemiological studies. The open access paper reports on data that suggests even very low levels of exercise correlate with a surprisingly large difference in life expectancy in comparison to sedentary individuals. This isn't an excuse to slack off if you happen to be somewhere closer to the recommended level of physical activity, however: there is plenty of evidence to suggest that optimal exercise benefits require twice that amount or more.

Strong evidence shows that physical activity has beneficial effects on well-being, health, and longevity in older ages. The survival effect of physical exercise has received support by a large study of more than 40,000 athletes, which shows that the Standardized Mortality Ratio (SMR) for athletes compared to the standard population was 33% lower. There are also other studies showing that physical exercise decreases mortality. In one study it was found that jogging or brisk walking more than 7.5 hr every week was associated with a higher life expectancy. In another study, for a person engaged in more frequent physical activity, the mortality risk was about 25% lower than for those less frequently active.

The longevity effect of physical activity seems, however, in a number of studies, in which both light and intense physical activity levels have been used, to be U-shaped according to frequency and intensity. Some researchers have tried to establish a dose-response relationship between the amount of exercise and decrease of mortality. Assuming the existence of a U-shaped relationship, moderate activity levels seem most preferable. This assumption has also been empirically supported with regard to the relationship between the amount of exercise and cardiac morbidity, quality of life and cognitive functioning. In addition, people with more frequent moderate physical activity (MPA) were engaged in more cognitive activities. It has also been found that only one to two hours of jogging weekly decreased the risk by 71%.

Assuming the existence of a U-shaped relationship, it has been suggested that while the largest decrease in the risk of death takes place when going from zero to any moderate physical activity, more frequent and intense physical activity is beneficial only for a very small part of the population, such as trained athletes. In this study, a sample of 8,456 individuals aged 60 to 96 years, representative of the Swedish population, was included. Participants were followed from 2004 to 2015. The results show that 82.1% of the total sample performed MPA 2 to 3 times every month or more, and those were, in an 11-year perspective, more often still alive.

In comparison with other studies, the low frequency of MPA needed for an effect on longevity was remarkable, although low levels have been suggested previously. The results do not contradict the general recommendations of daily moderate physical activity, but the present results also indicate that health advantages, at least in terms of longevity, can be achieved by an even lower activity frequency. The previously made suggestion that the strongest difference in health outcomes can be observed between those not active at all and those performing any moderate activity is confirmed by the result of this study.



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