Short spells of movement help, but research finds overall time spent seated must be cut
Are you sitting comfortably? Then get up and move about – even if it is just a walk about the office. That is the advice from experts who say periods of sitting must be replaced with exercise in order to ward off an early death.
Previous research from the same team found people should move at least every 30 minutes to reduce the chance of premature death, but now the researchers say simply breaking up sedentary periods is not enough – overall time spent seated must be cut to lower the risk.
While heart-pumping exercise offers the greatest gains, the study suggests even short, simple periods of movement bring benefits.
“When you take a movement break it doesn’t matter what you do, you can take a nice stroll down the hall,” said Dr Keith Diaz, an expert in behavioural medicine at Columbia University and co-author of the study.
Diaz noted such periods could be as short as a minute in duration. “It is about just accruing enough activity across the day,” he said, adding that walking to a co-worker’s desk rather than speaking on the phone, or having walking meetings, were both ways in which sitting time could be reduced and activity boosted.
Writing in the American Journal of Epidemiology, Diaz and colleagues report how they analysed data from almost 8,000 adults in the US aged 45 or older who were part of a broader study looking at the risk of stroke. Each participant wore an activity tracker for between four and seven days between 2009 and 2013, and almost 650 participants had died by April 2017.
Overall, participants were sedentary for an average of 694 minutes, or 11.5 hours, during their waking hours.
After taking into account factors including age, sex, race, smoking and a host of potential health problems, the team found that replacing sitting with moving reduced the risk of death.
More specifically, switching out 30 minutes of sedentary time over the course of the day for 30 mins of low-intensity activity reduced the risk of an early death by about 17%. If sitting was replaced with 30 minutes of heart-pumping activity such as running or cycling, the risk of an early death was reduced by 35%. However, the benefits were only seen among those who were not highly active to start with.
Moreover, the team found there were no benefits to be had if the total amount of sitting in a day remained the same but was broken up into short bouts.
“Sitting is harmful and is going to increase your risk [of death], no matter how you sit, whether it is in short bouts or long bouts,” said Diaz.
But, he added, that did not necessarily contradict the previous research, as that study had not considered how much low-intensity activity people did during the day. “The reason that people who took a break every 30 minutes had a lower risk of death is because they simply had more opportunity to move,” said Diaz.
Drawbacks of the latest study include that it did not look at whether the results held for younger people, movement data was only collected for a brief period of time, health data was only collected at one point, and participants were only followed up over a short period, so cause and effect is not clear.
Stuart Biddle, professor of physical activity and health at the University of Southern Queensland, who was not involved in the study, said it had long been known that too much sitting was linked to poor health. “But when you stop sitting, you must replace it with something else. This can only be light, moderate or vigorous-intensity physical activity, or sleep,” he said.