Sit Less, Live Longer?

If people need motivation to get up from their office chairs or couches and become less sedentary, two useful new studies could provide the impetus.

One found that sitting less can slow the aging process within cells, and the other underscores that standing up can be good for you as well.

For most of us nowadays, sitting is our most common waking activity, sitting for eight hours or more every day … Past studies have found that the more hours that people spend sitting, the more likely they are to develop diabetes, heart disease and other conditions, and potentially to die prematurely.

So the British Journal of Sports Medicine, scientists in Sweden decided to mount an experiment. They would alter the time that people spent exercising and sitting, and track certain physiological results.  In particular whether changes in sedentary time would affect people’s telomeres.

If you are unfamiliar with the componentry of your genes, telomeres are the tiny caps on the ends of DNA strands. They shorten and fray as a cell ages, although the process is not strictly chronological.

Obesity, illness and other conditions can accelerate the shortening, causing cells to age prematurely, while healthy lifestyles may preserve telomere length, delaying cell aging.



For the new experiment, the Swedish scientists recruited a group of sedentary, overweight men and women, all aged 68, and drew blood to measure the length of telomeres in the volunteers’ white blood cells. Then half began an individualized, moderate exercise program, and were advised to sit less.

The others were told to continue with their normal lives, and to try to lose weight and be healthy, without offering any specific methods.

After six months, they had a second blood draw and to complete questionnaires about their daily activities. … When the scientists compared telomeres, they found that the telomeres in the volunteers who were sitting the least had lengthened. Their cells seemed to be growing physiologically younger.

Meanwhile, in the control group telomeres generally were shorter than six months before.

But perhaps most interesting, there was little correlation between exercise and telomere length. In fact, the volunteers in the exercise group who had worked out the most during the past six months tended now to have slightly less lengthening and even some shortening, compared to those who had exercised less but stood up more.

Reducing sedentary time had lengthened telomeres, the scientists concluded, while exercising had played little role …Peter Katzmarzyk, a professor of public health at the Pennington Biomedical Research Center in Baton Rouge, La., and an expert on sedentary behavior, turned to a large database of self-reported information about physical activity among Canadian adults. The results, published in May in Medicine & Science in Sports & Exercise found that “mortality rates declined at higher levels of standing,” suggesting that standing is not sedentary or hazardous, a conclusion with which our telomeres would likely concur.


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