Less time spent seated linked to lengthening of telomeres

Curbing the amount of time spent sitting down might help to protect ageing DNA and therefore possibly extend the lifespan, suggests a small Swedish study published in the British Journal of Sports Medicine. According to the findings, the reduction of sedentary activity appears to lengthen telomeres, which sit on the end of chromosomes, the DNA storage units in each cell.

“To put it simple, it’s more important to get up from the couch and start moving in everyday life, than to put in hard training for the marathon”, says study co-author Mai-Lis Hellénius, Professor at Karolinska Institutet.

The study was conducted by a team of researchers from Karolinska Institutet, and the universities in Uppsala and Umeå, Sweden. The researchers analysed the length of chromosomal telomeres in the blood cells of 49 predominantly sedentary and overweight people in their late 60s, on two separate occasions, six months apart. All participants had been part of a previously reported clinical trial in which half of them had been randomly assigned to a tailored exercise programme over a period of six months, and half had been left to their own devices.

Telomeres are important because they stop chromosomes from ‘fraying’ or clumping together and ‘scrambling’ the genetic codes they contain, performing a role similar to the plastic tips on the end of shoelaces, to which they have been likened. Longevity and a healthy lifestyle have been linked to telomere length, but whether physical activity can make any difference is not clear. Researchers therefore were interested in investigate if the exercise programme had any effect on the length of telomeres.

Reductions in sitting time

Various risk factors for heart disease and stroke also improved in both groups, particularly those on the exercise programme, who also lost a great deal more weight than their counterparts left to their own devices. But increases in physical activity seemed to have less of an impact than reductions in sitting time, the findings showed.

“Our study shows, that a reduction in the amount of time spent sitting down in the group on the exercise programme was significantly associated with telomere lengthening in blood cells”, says Mai-Lis Hellénius. “Interestingly enough, increases in physical activity seemed to have less of an impact than reductions in sitting time. The number of daily steps taken was for example not associated with changes in telomere length, which shows just how complex this phenomenon of physical activity is.”

First study author was Dr. Per Sjögren at Uppsala University. The work was supported by grants from the Swedish Cancer Society, Swedish Research Council, County Council of Västerbotten, the Swedish Heart-Lung Foundation, EU’s Seventh Framework Programme amongst other organisations (full list in the article). The discovery of the functions of the telomeres was awarded the Nobel Prize in Physiology or Medicine in 2009.

• Read a column about the findings in The New York Times
• Find a press release from BMJ Publishing about this study

Publication

Stand up for health—avoiding sedentary behavior might lengthen your telomeres: secondary outcomes from a physical activity RCT in older people
Per Sjögren, Rachel Fisher, Lena Kallings, Ulrika Svenson, Göran Roos, Mai-Lis Hellénius
British Journal of Sports Medicine, online 3 september 2014, doi: 10.1136/bjsports-2013-093342