Secret to youth: Low levels of physical activity can make your cells age faster, says a new study.
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SYDNEY: Yet another reason to get off the couch: physically active people don't just look better – they may be biologically younger too.
British researchers examined 2,401 twins and found that those who reported having an active lifestyle had biological markers which appeared to be as much as ten years younger than those of their less active twins.
"A sedentary lifestyle increases the propensity to aging-related disease and premature death," said Lynn Cherkas, geneticist at King's College in London, U.K., and lead author of the study published in the American Medical Association journal, the Archives of Internal Medicine.
Age-related diseases
Inactivity may diminish life expectancy not only by predisposing people to ageing-related diseases – such as diabetes, high blood pressure and heart disease – but also because it may influence the ageing process itself.
Cherkas and her team asked the twins to fill out a questionnaire on physical activity level, smoking habits and socio-economic status and also took a blood sample. They then extracted DNA from their white blood cells and determined the length of repetitive genetic sequences at the end of chromosomes known as telomeres.
Telomeres play an important role in cellular division and control the lifespan of a cell. Like slow-burning fuses, their length decreases with age, with an average loss of 21 structural units per year. They are also believed to play an important role in the aging process itself.
The researchers found that the telomeres of both male and female twins who were less active were significantly shorter than the telomeres of their siblings who were physically active in their leisure time.
"The most active subjects… had telomeres on average 200 base pairs longer than the [most] inactive subjects," said Cherkas. "Which means that on average most active subjects had telomeres the same length as individuals up to 10 years younger."
The trend between telomere length and physical activity level remained significant even after adjustment for associated factors such as weight, smoking, socio-economic status and physical activity at work, wrote the authors.
Inflammation and damage caused to cells by free radicals are likely mechanisms by which sedentary lifestyles shorten telomeres, they suggest. Regular physical activity can also reduce psychological stress, which has also been linked to telomere length, they said.
Powerful message?
"U.S. guidelines recommend that 30 minutes of moderate-intensity physical activity at least five days a week can have significant health benefits," write the authors. "Our results underscore the vital importance of these guidelines… [and provide] a powerful message to clinicians to promote the potentially anti-aging effect of regular exercise."
Molecular geneticist Phillip Morris of the Queensland University of Technology in Brisbane, argued that the study takes its conclusions too far, however.
"To suggest that people live longer because they have longer telomeres seems to me that they have stretched their data beyond its reasonable limits," he said. "Nobody has really established that telomere length is correlated with the lifespan of the organism, but it does seem to be related to how old cells age when they grow in culture."
"It's quite circumstantial evidence, with no solid ties between an observation about telomeres and a direct correlation with age and life expectancy," added Morris.
with Agence France-Presse
