Dec. 1, 2009 -- People who exercise regularly tend to stay healthier as they age, and now new research may explain why at a cellular level.
Compared to people who did not exercise, elite runners in the study had cells that looked much younger under a microscope.
Specifically, investigators measured the length of telomeres -- the DNA on either end of thread-like chromosomes.
Just as the plastic tips on the ends of shoelaces keep the laces from fraying, telomeres protect the chromosomes that carry genes during cell division.
Each time a cell divides, telomeres get shorter. When telomeres get too short, cells can no longer divide and they die.
Researchers now believe telomere shortening is critical to aging, making people more vulnerable to diseases such as heart disease, diabetes, and cancer.
“Telomeres can be thought of as a biological clock,” lead researcher Ulrich Laufs, MD, of Homburg, Germany’s Saarland University tells WebMD. “If they are shorter than a critical length, the process of programmed cell death starts.”
Exercise and Telomeres
The new research involved animal and human studies designed to determine how exercise impacts telomere length.
In the animal studies, mice that ran on a running wheel for as little as three weeks showed evidence of increased production of telomere-stabilizing proteins, which protected against cell death.
In the human studies, middle-aged professional athletes who ran about 50 miles a week and had done so for many years had longer telomeres than healthy, age-matched non-athletes who did not exercise regularly.
The study appears in the Dec. 15 issue of the American Heart Association journal Circulation.
“This is the first time it has been shown at the molecular level that exercising has an antiaging effect on the cardiovascular system,” Laufs says.
American Heart Association spokesman Barry Franklin, PhD, calls the new research "phenomenal."
“In many respects, I think this is a blockbuster study that complements research in twins published last year,” he tells WebMD.
Exercise May Trump Genes
That study suggested exercise might trump genes when it comes to keeping people young.
Researchers found that telomere length was related to activity level. People who engaged in the most exercise had telomeres of similar length to inactive people up to 10 years younger.
When one twin was largely sedentary and the other was active, the active twin tended to have longer telomeres.
The most active people in the twin study engaged in just a few hours of moderate to vigorous activity a week, suggesting that it is not necessary to run 50 miles a week to achieve the antiaging benefits of exercise.
“In my own lab, I have seen a 3-month conditioning program raise oxygen capacity significantly,” Franklin says.
He is director of cardiac rehabilitation and the exercise laboratories at the William Beaumont Hospital in Royal Oaks, Mich.
“In both studies, active people had cells that were measurably younger than inactive people,” he says. “This striking finding may explain how exercise helps prevent heart attacks, diabetes and other degenerative diseases.”