People who are physically active in their free time may be biologically younger 1 than couch potatoes, a new British study suggests.

"A sedentary lifestyle increases the propensity to aging-related diseases and premature death. Inactivity may diminish life expectancy not only by predisposing to aging-related diseases, but also because it may influence the aging process itself," said study author Lynn F. Cherkas, of King's College, London.

The study was published in the Archives of Internal Medicine.

The Study

The researchers looked at the physical activity levels, smoking habits and socioeconomic status of 2,401 white twins.

The researchers also collected DNA samples from participants, and examined the length of telomeres-repeated sequences at the end of chromosomes in white blood cells (leukocytes). Leukocyte telomeres shorten over time and may serve as a marker of a person's biological age.

Overall, the study participants had an average telomere loss of 21 nucleotides (structural units) per year. However, researchers noted, those who were more active in their leisure time had longer leukocyte telomeres than those who were less active.

"Such a relationship between leukocyte telomere length and physical activity remained significant after adjustment for body-mass index, smoking, socioeconomic status and physical activity at work," said the study authors.

"The mean difference in leukocyte telomere length between the most active (those who performed an average of 199 minutes-- just over 2% hours-of physical activity per week) and least active (16 minutes of physical activity per week) subjects was 200 nucleotides," the researchers


Translation: This means that the most active subjects had telomeres the same length as sedentary individuals up to 10 years younger, on average.

Possible Explanations

Oxidative stress damage caused to cells by exposure to oxygen and inflammation may be a factor contributing to shorter telomere length in sedentary people.

Stress has also been linked to telomere length. Exercise may reduce stress and its effect on telomeres and the aging process, the study authors suggested.


According to researchers, "The US guidelines recommend that an exercise regimen of 30 minutes of moderate-intensity physical activity at least five days a week can have significant health benefits."

"Our results underscore the vital importance of these guidelines. They show that adults who partake in regular physical activity are biologically younger than sedentary individuals," said the authors.

But more research is needed to confirm a direct link between physical activity and aging, the study noted.

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