Physically active people are biologically younger than the couch potatoes, a study published Monday in the Archives of Internal Medicine has found.(File Photo)

Physically active people are biologically younger than the couch potatoes, a study published Monday in the Archives of Internal Medicine has found.

A long-term health study based on 2,401 twins found that those who had an active lifestyle appeared to be as much as ten years younger biologically than those of the more sedentary ones.

The researchers extracted DNA from the participants' white blood cells and examined the chromosomes to determine the length of a genetic sequence called telomeres, which were found at the ends of chromosomes.

Telomeres get shorter when a cell divides. When telomeres get too short, cells stop dividing. Aging occurs as more and more cells reach the end of their telomeres and die.

The study suggested the moderately active subjects who averaged 100 minutes of physical activity a week had telomeres that on average looked five or six years younger than the least active subjects who averaged 16 minutes a week. Those who did the most -- doing 199 minutes on average a week had telomeres that appeared to be about nine to ten years younger than those who did the least.

"These data suggest that the act of exercising may actually protect the body against the aging process," said Tim D. Spector, a professor of genetic epidemiology at King's College in London who led the study.

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

Researchers said they hoped doctors could use the findings to encourage people to exercise.

"Hopefully, when clinicians are advising patients, this could be another reason to offer," Spector said. "It may slow down the aging process, and people may actually look and feel younger, which we know would be a good thing for most of the population."

(Agencies via Xinhua News Agency January 29, 2008)