Stand more, live longer study finds

If you want to live longer, be on your feet longer – that seems to be a key finding in a study of the effect of sitting on human life span.

The new research published in the British Journal of Sports Medicine, revealed that changes in time spent being sedentary could cause changes in the DNA that could slow down the ageing process.

In the study, scientists from Sweden selected a group of sedentary, obese volunteers, all aged 68.

They drew blood from the participants to extract the DNA from their cells and the length of telomeres, end caps that protect the DNA from shortening, was measured.

Half of the volunteers were asked to follow an individualised exercise regimen to improve their overall health and were advised to follow a less sedentary lifestyle and sit less. Rest of the volunteers followed their routine unchanged.

Following a six month-period, blood was drawn from all the participants to analyse the telomere ends of the DNA in their cells, and it was found that volunteers who were active and sitting the least had lengthened telomere ends in their cells.

Their cells seemed to be growing physiologically younger, while participants who had continued with their routine sedentary habits had comparatively shorter telomeres.

Perhaps, the most interesting finding was that there was little correlation between exercise and telomere length. Rather, volunteers in the exercise group who had worked out the most during the past six months tended to have slightly less lengthening and even some shortening, as against those who had exercised less but stood up more.

According to Per Sjögren, a professor of public health at Uppsala University in Sweden, exactly what the volunteers did in lieu of sitting was impossible to say with precision, but it was most likely, he said, that ''sitting time was predominantly replaced with low-intensity activities,'' and particularly with time spent standing up.

Standing was not, physically demanding for most people, and some scientists had questioned whether merely standing up - without also moving about and walking - was sufficiently healthy.

If that were the case, standing could be expected to increase health problems and premature death, as sitting had been shown to do.

To find out, Peter Katzmarzyk, a professor of public health at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, and an expert on sedentary behaviour, studied a large database of self-reported information about physical activity among Canadian adults.

Katzmarzyk noted the amount of time that the men and women had reported standing on most days over the course of a decade or more and compared the data with death records, to see whether people who stood more died younger.

He did not find any link between standing and premature death. Rather, he found, ''mortality rates declined at higher levels of standing,'' suggesting that standing was not sedentary.