Just a little moderate to vigorous physical activity-below the recommended amount-every week still seems to curb the risk of death among the over 60s, suggests an analysis of the available evidence published online in the British Journal of Sports Medicine.
The health benefits of 150 minutes a week of moderate to vigorous physical activity are well known, but older adults often find it difficult to reach this target, say the researchers, who wanted to know if any regular amount of activity below this level was associated with greater longevity in this age group.
They therefore trawled relevant research databases for studies published up to February 2015, which assessed risk of death according to weekly physical activity for those aged 60 and above.
Physical activity was measured in Metabolic Equivalent of Task (MET) minutes, which express the amount of energy (calories) expended per minute of physical activity.
One MET minute is equal to the energy equivalent of just sitting, and how many MET minutes an individual clocks up every week depends on the intensity of physical activity s/he does.
For example, moderate intensity activity ranges between 3 and 5.9 MET minutes while vigorous intensity activity is classified as 6 or more. The current US recommendation is for a tally of between 500 and 1000 MET minutes every week.*
The researchers looked at the associated risk of death for four categories of weekly physical activity: inactive; low (1-499); medium (500-999); and high (1000+).
Out of a total of 835 relevant studies, nine were suitable for analysis. These involved a total of 122, 417 participants, who were monitored for an average of around 10 years. During this period, 18,122 died.
Pooled analysis of the data showed that clocking up less than 500 weekly MET minutes of physical activity was still associated with a 22% lowered risk of death compared with those who were inactive.
The more physical activity an individual engaged in, the greater the health benefit, reaching a 28% lower risk of death for those fulfilling the recommended weekly tally of MET minutes, while more than 1000 MET minutes was associated with a 35% lower risk.
The greatest benefit seemed to be among those who went from doing nothing or only a minimal amount of physical activity to doing more.
Much of the health benefit seemed to be for a reduced risk of dying from heart disease/stroke, while the reduction in deaths from all causes was considerably greater in older women than it was in older men.
The data showed that a weekly tally of 250 MET minutes, which corresponds to 75 minutes of moderate to vigorous physical activity-or 15 minutes a day-was associated with health benefits, added to which the first 15 minutes of physical activity seemed to have the greatest impact, prompting the researchers to suggest that this could be "a reasonable target dose."
They conclude: "Based on these results, we believe that the target for physical activity in the current recommendations might be too high for older adults and may discourage some of them...The fact that any effort will be worthwhile may help convince those 60% of participants over 60 years of age, who do not practice any regular physical activity, to become active."