In 2010-12, the 3137 survivors were invited for a check-up, involving a physical examination, and questions about their lifestyle, sleeping patterns, and whether they had ever been diagnosed with heart disease. The participants were also fitted out with an accelerometer each. Accelerometers are portable gadgets that continuously track the volume and intensity of physical activity. Participants were required to wear said gadgets during waking hours for 7 days. Their health was then tracked until death or June 2016, whichever came first.
1566 (50% of participants) men agreed to wear the device, but after excluding those with pre-existing heart disease and those who hadn’t worn their accelerometer enough during the 7 days, the final analysis was based on 1181 men, whose average age was 78. During the monitoring period, which averaged around 5 years, 194 of the men died.
The accelerometer findings indicated that total volume of physical activity was associated with a lower risk of death from any cause. Every additional 30 minutes a day of light intensity activity, (such as pruning the roses, or taking the dog for a walk) was associated with a 17 percent reduction in the risk of death. This association persisted even after researchers took into account potentially influential lifestyle factors, such as sedentary time.
Although the equivalent reduction in the risk of death was around 33 percent for each additional 30 minutes of moderate to vigorous intensity physical activity a day, the benefits of light intensity activity were large enough to mean that this too might prolong life.
Moreover, there was no evidence to suggest that clocking up moderate to vigorous activity in bouts of 10 minutes or more was better than accumulating it in shorter bouts. In short, sporadic bouts of activity were associated with a 41 percent lower risk of death; bouts lasting 10 or more minutes were associated with a 42 percent lower risk.
These sporadic bouts seemed easier to achieve; two thirds (66%) of the men achieved their weekly total of moderate to vigorous physical activity in this way while only 16% managed to do so in bouts of 10 or more minutes. Finally, there was no evidence to suggest that breaking up sitting time was associated with a lower risk of death.
Given that this is an observational study, no firm conclusions can be drawn about cause and effect. Moreover, those who wore the accelerometer tended to be younger and have healthier lifestyles than those who didn’t, so this might have skewed the results. Additionally, it is unclear whether these findings would be equally applicable to younger age groups or older women.
However, the results could be used to refine current physical activity guidelines and make them more achievable for older adults. All physical activity, even that of low intensity, is worthwhile for extending the lifespan. According to the researchers, this is particularly important to recognise, given how physical activity levels tail off rapidly as people age:
“[The] results suggest that all activities, however modest, are beneficial. The finding that [low intensity physical activity] is associated with lower risk of mortality is especially important among older men, as most of their daily physical activity is of light intensity,” write the researchers.
“Furthermore, the pattern of accumulation of physical activity did not appear to alter the associations with mortality, suggesting that it would be beneficial to encourage older men to be active irrespective of bouts,” they add.