Just a few minutes of light intensity exercise linked to lower death risk in older men

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Clocking up just a few minutes at a time of any level of physical activity, to tally 150 minutes a week, is linked to a lower risk of death in older men, suggests research from University College London, University of Bristol, Brigham and Women’s Hospital, Boston, and St George’s University of London. Providing the recommended 150 minute weekly tally of moderate to physical activity is reached, total volume, rather than activity in 10 minute bouts, as current guidelines suggest, might be key, the findings indicate. This lower level of intensity is also likely to be a better fit for older men, most of whose daily physical activity is of light intensity, say the researchers.

Current exercise guidelines recommend accumulating at least 150 minutes a week of moderate to vigorous physical activity in bouts lasting 10 or more minutes. But such a pattern is not always easy for older adults to achieve, say the researchers.

To find out if other patterns of activity might still contribute to lowering the risk of death, the researchers drew on data from the British Regional Heart Study. This involved 7,735 participants from 24 British towns, who were aged between 40 and 59 when the study stated in 1978-80.

In 2010-12, the 3,137 survivors were invited for a check-up, which included a physical examination, and questions about their lifestyle, sleeping patterns, and whether they had ever been diagnosed with heart disease.

They were also asked to wear an accelerometer–a portable gadget that continuously tracks the volume and intensity of physical activity–during waking hours for 7 days. Their health was then tracked until death or June 2016, whichever came first.

In all, 1,566 (50%) 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, from light intensity upwards, was associated with a lower risk of death from any cause.

Each additional 30 minutes a day of light intensity activity, such as gentle gardening or taking the dog for a walk, for example, was associated with a 17% reduction in the risk of death. This association persisted even after taking account of potentially influential lifestyle factors, such as sedentary time.

Whilst the equivalent reduction in the risk of death was around 33% 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.

And 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. Sporadic bouts of activity were associated with a 41% lower risk of death; bouts lasting 10 or more minutes were associated with a 42% lower risk.

Sporadic bouts seemed easier to achieve as 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.

This is an observational study so no firm conclusions can be drawn about cause and effect. And 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, say the researchers. Nor is it clear if the findings would be equally applicable to younger age groups or older women.

Nevertheless, the results could be used to refine current physical activity guidelines and make them more achievable for older adults, suggest the researchers.

Future guidance might emphasise that all physical activity, however modest, is worthwhile for extending the lifespan–something that is particularly important to recognise, given how physical activity levels tail off rapidly as people age, they point out.

“(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.

Objectives To understand how device-measured sedentary behaviour and physical activity are related to all-cause mortality in older men, an age group with high levels of inactivity and sedentary behaviour.
Methods Prospective population-based cohort study of men recruited from 24 UK General Practices in 1978–1980. In 2010–2012, 3137 surviving men were invited to a follow-up, 1655 (aged 71–92 years) agreed. Nurses measured height and weight, men completed health and demographic questionnaires and wore an ActiGraph GT3x accelerometer. All-cause mortality was collected through National Health Service central registers up to 1 June 2016.
Results After median 5.0 years’ follow-up, 194 deaths occurred in 1181 men without pre-existing cardiovascular disease. For each additional 30 min in sedentary behaviour, or light physical activity (LIPA), or 10 min in moderate to vigorous physical activity (MVPA), HRs for mortality were 1.17 (95% CI 1.10 to 1.25), 0.83 (95% CI 0.77 to 0.90) and 0.90 (95% CI 0.84 to 0.96), respectively. Adjustments for confounders did not meaningfully change estimates. Only LIPA remained significant on mutual adjustment for all intensities. The HR for accumulating 150 min MVPA/week in sporadic minutes (achieved by 66% of men) was 0.59 (95% CI 0.43 to 0.81) and 0.58 (95% CI 0.33 to 1.00) for accumulating 150 min MVPA/week in bouts lasting ≥10 min (achieved by 16% of men). Sedentary breaks were not associated with mortality.
Conclusions In older men, all activities (of light intensity upwards) were beneficial and accumulation of activity in bouts ≥10 min did not appear important beyond total volume of activity. Findings can inform physical activity guidelines for older adults.
This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited.

Barbara J Jefferis, Tessa J Parsons, Claudio Sartini, Sarah Ash, Lucy T Lennon, Olia Papacosta, Richard W Morris, S Goya Wannamethee, I-Min Lee, Peter H Whincup

BMJ material
British Journal of Sports Medicine abstract

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