“Pottering around the garden or walking the dog is enough to help older men live longer,” reports The Daily Telegraph.

UK researchers used monitors to track the activity levels of 1,181 men aged 71 to 92. They found those who were the most active were likely to live longer.

People in the UK are advised to take at least 150 minutes of moderate to vigorous physical activity a week in bouts of 10 minutes or more.

But the study found even light activity was beneficial. It didn’t matter how long each bout of activity lasted, as long as the target of 150 minutes a week was met.

The problem with this type of study is that it’s hard to know whether people live longer because they do more physical activity, or whether they do more activity because they’re generally in better health and so live longer.

Even though the researchers tried to account for other factors that might have affected how long the men lived, this study can’t prove that being more active increases your lifespan.

That said, the study’s take-home message is simple and positive: short bouts of light activity of any duration all add up and may increase your chances of living longer.

If you can only manage a short walk or some gentle gardening, that’s a lot better than doing nothing.

Where did the story come from?

The study was carried out by researchers from University College London, Bristol Medical School and St George’s Medical School London in the UK, and Harvard Medical School in the US.

It was funded by the British Heart Foundation and the National Institute of Health Service Research.

The study was published in the peer-reviewed British Journal of Sports Medicine and is free to read online.

The study was widely reported, with most UK media reports being reasonably accurate.

The emphasis on “a few minutes of light exercise” being enough to help people live longer, however, could make people think there’s no point in doing more than that.

In fact, the study showed that the more active people were, the better.

What kind of research was this?

This was part of a long-term cohort study involving survivors of a study that began in 1978.

Researchers wanted to investigate the effects of objectively measured physical activity on length of life in older men.

Cohort studies are a good way to spot patterns and links between factors – in this case, physical activity and length of life – but they can’t prove that one directly causes the other.

What did the research involve?

Researchers approached 3,137 men who were part of a long-running study of men’s health.

They asked them to come for a health check and to wear an activity monitor for 7 days. They followed them up until the end of the study (an average of 5 years).

They then looked at how many men survived to the end of the study, and whether their activity measures at the start of the study were linked to their chances of still being alive.

The researchers adjusted their figures to take account of potential confounding factors.

The activity monitors recorded:

• minutes spent in sedentary activity (such as sitting or lying down)
• minutes spent in light activity, such as gentle walking
• minutes spent in moderate to vigorous activity, such as brisk walking or cycling

As well as total time, the monitors tracked bouts of activity – for example, hours spent sitting down without moving or minutes spent walking without a break.

Potential confounding factors included:

• cigarette smoking and alcohol consumption
• usual length of sleep at night
• whether the men lived alone
• cardiovascular disease at the start of the study
• walking disability
• social class and geographical region

What were the basic results?

Half the men approached agreed to take part. Researchers excluded those who’d had a heart attack, heart failure or stroke.

They had sufficient activity monitor data to include 1,274 men in the study.

The average time men spent wearing the activity monitor was 855 minutes (14 hours) a day.

Average activity levels were:

• 616 minutes spent sedentary
• 199 minutes spent in light activity
• 33 minutes spent in moderate or vigorous activity

Men who were more active were likely to be younger (average age was 78), non-smokers and drink less alcohol, and less likely to have a walking disability.

During the 5 years they were followed up, 194 men died.

Time spent sedentary or active was linked to how likely people were to have lived to the end of the study:

• each additional 30 minutes a day spent sedentary was linked to a 15% increase in chances of death (hazard ratio [HR] 1.15, 95% confidence interval [CI] 1.07 to 1.23)
• each additional 30 minutes a day spent doing light activity was linked to a 15% reduction in chances of death (HR 0.85, 95% CI 0.78 to 0.92)
• each additional 30 minutes a day spent doing moderate to vigorous activity was linked to an 8% reduction in chances of death (HR 0.92, 95% CI 0.86 to 0.98)

Men who managed the government target of 150 minutes of moderate to vigorous activity each week were about 40% less likely to have died by the end of the study, regardless of whether they did this in bouts of 1 to 9 minutes, or bouts of 10 minutes and more.

How did the researchers interpret the results?

The researchers said their results “could refine physical activity guidelines and make them more achievable for older adults with low activity levels” by “stressing the benefits of all activities, however modest”.

They added that guidelines should encourage “accumulating activity of all intensities without the need to sustain bouts of 10 minutes or more”.

Conclusion

The importance of staying active in older age is becoming increasingly clear, but many older people find it difficult to meet targets set for the wider population.

This study provides useful information about physical activity levels in a group of older men in the UK and how activity may be linked to length of life.

It’s particularly useful that the group wore activity monitors, as much research about physical activity is based on people estimating what they did, which can be inaccurate.

But this study has some limitations. It only involved older men in the UK, who were mostly white, so the results may not translate to women, other ethnic groups, or younger men.

Although the researchers tried to account for confounding factors, these may still have some unmeasured effects.

That means we can’t be completely sure that physical activity was the reason that the more physically active men lived longer.

And activity monitors can’t always tell the difference between someone sitting still and standing still, so may overestimate sedentary time.

The general message of the study is positive for older people: it’s worth keeping active, even if you can’t do very vigorous activity.

Short bursts of gentle activity of any duration all add up and may increase your chances of living longer.