Sedentary stretches are okay if…

Now policy makers must start taking the numbers more seriously

By Joan Cohen

Exercise!! The evidence mounts that the payoff can be huge: good health and a lifespan more like the one nature probably intended for us. And with some new research findings, there’s especially good news for people who daily sit at a desk or workbench or are otherwise sedentary for long hours.

The sedentary life will not kill you or bring on health problems if you are moderately active in your daily life, according to a meticulously organized study just published in the British medical journal, The Lancet. An hour a day of exercise or moderate activity will nullify the damaging effect eight or more hours of sitting can have on the human body.

Four years ago, this same journal released studies finding that physical inactivity imposes human health risks as important as those from smoking and inactivity, and underlining the importance of dealing with that much-neglected risk. In a new study, The Lancet looks at the effects of moderate activity in countering the risks to life posed by varying amounts of sedentary behaviour. In a separate report, it pleads with policy makers to “take physical activity more seriously”.

In doing its systematic review, the journal’s research team first went on a search for existing databases showing individual behaviour and the outcomes of that behaviour. These data bases set out daily sitting times or, alternatively,TV-viewing times and then that same individual’s physical activity, and combined this material with the person’s corresponding mortality data.

In this follow-up study, some one million people were tracked for two to 18 years, ending in 2015. It is the largest harmonized follow-up analysis (consolidating earlier analytic studies) yet produced on the joint health effects of sedentary behaviour and physical activity. During the course of the study, 84,000 people died. (Mortality rates were substantially higher in lower activity groupings).

For both sedentary behaviour and physical activity, participants data were fitted into one of four quartiles, related to length of time for the sedentary part and then to energy expended in levels measuring physical activity. Participants were then further divided into two separate groups, as sedentary individuals or as TV-viewers. In the end, most high-level TV viewers were found to draw minimal or no benefit from their physical activity.

The ultimate finding: “High levels of moderate intensity physical activity – some 60 to 75 minutes per day –appeared to eliminate the increased risk of death associated with high sitting time,” said the report.

“These results provide further evidence on the benefits of physical activity, particularly in societies where increasing numbers of people have to sit for long hours for work,” the report summarily pointed out.

Note: The phrase “Moderate activity” or “moderate intensity exercise” covers a range of activities. Here are a few: brisk walking, bicycling at five to nine miles per hour on level terrain or stationary bicycling using moderate effort, playing doubles tennis, yoga, golf – wheeling or carrying clubs, ballroom dancing, pushing a lawn mower or general gardening, shovelling light snow or playing with the kids.

Note, too, that where vigorous activity is in play, a lower level of activity would be needed in these calculations to offset extensive sitting. High activity would include jogging or running, bicycling at more than 10 mph, using a rowing machine, energetic square dancing.

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