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'Sit less, move more' may be key advice for living longer

Thursday 22 August 2019

"Older adults can boost longevity 'with just a little exercise'," reports The Guardian.

It's long been known that being more physically active is linked to being healthy and living longer.

Now researchers who re-examined data from 8 studies, which included 36,383 people aged over 40, say the benefits are greater than previously thought, and that any intensity of activity helps.

Researchers found benefits were greatest for those who did:

  • 375 minutes (about 6 hours 15 minutes) a day of light-intensity physical activity, such as walking, cooking or gardening
  • 24 minutes a day of moderate to vigorous physical activity

People who managed those levels of activity cut the risk of premature death during the study by 50% to 60%, compared with people who were least active.

But even doing a little more activity helped. People who did about 60 minutes a day more of light activity, compared with those who were least active, had a 40% lower risk of death.

The researchers also found the risk of dying during the study was higher for people who spent the most time sitting down, with the risk starting to rise sharply after 9.5 hours a day spent sedentary.

The findings add weight both to current UK guidelines for physical activity for adults and to the advice we should sit less and move more.

Read more about the benefits of exercise and physical activity guidelines for older adults.

Where did the story come from?

The researchers who carried out the study came from institutions including the Norwegian School of Sport Sciences in Norway, University College London, St George's University of London and the University of Leicester in the UK, Columbia University Medical Center, San Diego State University, Boston University School of Public Health, Boston University School of Medicine, the National Institute of Ageing, Brigham and Women's Hospital and Harvard Medical School in the US, and the Karolinska Institutet in Sweden.

There was no specific funding for the study. It was published in the peer-reviewed British Medical Journal on an open access basis, so it's free to read the study online.

The study was enthusiastically covered in the UK media. Most took a positive tone, such as The Sun's advice to "Get Hoovering! Any exercise – even housework – lowers your risk of dying young".

The Daily Telegraph was more gloomy, warning: "Middle-aged adults who sit for more than nine hours a day double their risk of early death".

The reports were broadly accurate and balanced.

But the emphasis on the message that any activity was good, even a little of it, might obscure the message that more activity was better. Few people are likely to vacuum their house for 6 hours a day.

What kind of research was this?

This was a systematic review and meta-analysis of cohort studies.

Systematic reviews are the best way to get an overview of the state of evidence about a topic.

Meta-analysis allows researchers to pool data to get a more accurate picture of results from bigger numbers of trial participants.

Cohort studies are good ways to measure the links between lifestyle factors, such as activity, and outcomes, such as when people die.

But they cannot prove that 1 thing (activity levels) directly causes an outcome. Other factors may be involved.

What did the research involve?

Researchers looked for cohort studies where adults had been fitted with activity monitors, which track the amount of activity a person does, and their time spent sedentary.

They also looked at studies that had information about mortality (whether people died of any cause during the study or follow-up period).

Because studies did not all interpret activity monitor data in exactly the same way, the researchers asked the original study authors to re-analyse their data according to a standardised protocol.

This allowed them to combine the study findings in a harmonised meta-analysis.

Researchers looked at:

  • total physical activity
  • light physical activity
  • low duration of light activity
  • high duration of light activity
  • moderate to vigorous activity
  • vigorous activity
  • sedentary time

They divided people into 4 groups, from highest to lowest time spent in each type of activity.

They then compared the chances of death for people in the different groups, with the lowest activity group being the comparator group.

The analysis took account of people's age, sex, socioeconomic status and body mass index.

What were the basic results?

The 36,383 people, average age 62.6, included in the study were followed for an average 5.8 years. During that time, 2,149 (5.9%) of them died.

Compared with people who did the least physical activity overall, those who did the most were 73% less likely to have died (hazard ratio [HR] 0.27, 95% confidence interval [CI] 0.23 to 0.32).

But even those in the second-least active group cut their chances of death by 52%, compared with those doing the least (HR 0.48, 95% CI 0.43 to 0.54).

Light intensity

Higher levels of light intensity activity, as well as higher intensity activity, were also linked to a lower risk of death.

Compared with people who did the least activity, those who did the most light-intensity activity were 62% less likely to have died (HR 0.38, 95% CI 0.28 to 0.51).

Researchers said the link between light physical activity and longer life was strongest for people who did 375 minutes of light intensity activity a day.

But even doing a little more activity helped. People in the second least active group, who did about 60 minutes a day more light activity than those who were least active, had a 40% lower risk of death (HR 0.60, 95% CI 0.54 to 0.68).

Moderate to vigorous intensity

Higher levels of moderate to vigorous intensity activity also helped, although fewer people in the studies did this type of exercise, meaning the results may be less reliable.

The people who did the most moderate to vigorous physical activity were 48% less likely to die than those who did the least (HR 0.52, 95% CI 0.43 to 0.61).

The biggest reduction in risk of death was linked to doing 24 minutes a day of moderate to vigorous intensity, with no reduced risk seen after that.

Sedentary time

People who spent the most time sitting had the highest chance of death, compared with those who spent least time sitting.

They were 263% more likely to die – more than twice as likely.

The researchers said the risk of death associated with sitting started to go up between about 7 and 9 hours, with a sharper increase from 9.5 hours.

People who spent 12 hours a day sitting had almost a 3-fold increased risk of death (HR 2.92, 95% CI 2.24 to 3.83).

How did the researchers interpret the results?

The researchers said: "Our findings provide clear scientific evidence that higher levels of total physical activity – regardless of intensity level – and lesser amounts of sedentary time are associated with lower risk of premature mortality [early death]."

They added: "The public health message might simply be 'sit less and move more and more often'."

Conclusion

It's not news that being more physically active is likely to help you live a longer, healthier life. But this new study helps to show how great the benefit may be.

Focusing on studies that used more accurate measurement of activity levels (rather than relying on self-reported activity) may explain why this systematic review found bigger benefits from physical activity than previous systematic reviews.

The study is also useful because it looks in detail at the effects of low-intensity activity.

Especially as people age, they may be much less likely to want, or start, to do vigorous activities like playing sport or running.

The study shows that any type of activity is beneficial, and increasing the time you're up and moving about makes a difference, even if you do not think of it as exercise.

The study also adds to evidence that spending long periods of time inactive and sitting down is likely to be bad for health.

But the study does have limits. We do not know if the results apply to younger people, who may need to do more vigorous activity to keep fit.

Because it's an observational study, we cannot tell if higher physical activity definitely prevented premature death.

It could be, for example, that people who are already ill are less likely to be physically active. Or it could be that being active is linked to a healthier lifestyle overall, which could lead to longer life.

What we do know is that physical activity has been found to be good for our health in many studies.

This study adds to that mountain of evidence to suggest that we should all take the researchers' advice to "sit less and move more".

Find out about the recommended activity levels for adults

Analysis by Bazian
Edited by NHS Website