Yet another reason to get off the couch: physically active people don't just look better, they appear to be biologically younger as well, a study published Monday has found.

British researchers examined 2,401 Caucasian 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 more sedentary twins.

"A sedentary lifestyle increases the propensity to aging-related disease and premature death," wrote lead author Lynn Cherkas of King's College London.

"Inactivity may diminish life expectancy not only by predisposing to aging-related diseases (like diabetes, high blood pressure and heart disease) but also because it may influence the aging process itself."

Cherkas and her colleagues asked the twins to fill out a questionnaire on physical activity level, smoking habits and socioeconomic status and took a blood sample.

They then extracted DNA from the white blood cells and examined the chromosomes to determine the length of a genetic sequence called telomeres.

Telomeres play an important role in the cellular division and are found at the ends of chromosomes.

Their length decreased with age, with an average loss of 21 structural units per year, and they are believed to also play an important role in the aging process.

And these telomeres were significantly shorter in the men and women who were less physically active in their leisure time.

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

The mean difference between the most active subjects, who averaged 199 minutes of physical activity per week, and least active, who averaged 16 minutes of activity per week, was 200 nucleotides.

"Which means that the most active subjects had telomeres the same length as sedentary individuals up to 10 years younger" the authors wrote.

They found similar results when comparing twins with different levels of physical activity.

Inflamation and damage caused to cells by exposure to oxygen are likely mechanisms by which sedentary lifestyles shorten telomeres, the authors suggested.

Physical activity can also reduce psychological stress, which has also been linked to telomere length.

"The US guidelines recommend that 30 minutes of moderate-intensity physical activity at least five days a week can have significant health benefits," the authors wrote.

"Our results underscore the vital importance of these guidelines."

The study was published in the Journal of the American Medical Association's Archives of Internal Medicine.

WASHINGTON, Jan 28, 2008 (AFP)


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