Exercise is known to have a bounty of health benefits that can ward off age-related diseases, but a new study shows that regular physical activity has an anti-aging effect at the cellular level.
The research found that intensive exercise prevents the shortening of telomeres — the DNA that bookends chromosomes and protects the ends from damage — much like the cap on the end of a shoelace.
The shortening of telomeres limits cells to a fixed number of divisions and can be regarded as a "biological clock." Gradual shortening of telomeres through cell divisions leads to aging on the cellular level and may limit lifetimes. When the telomeres become critically short, the cell dies.
The researchers measured the length of telomeres in blood samples from two groups of professional athletes and two groups who were healthy nonsmokers, but not regular exercisers.
"The most significant finding of this study is that physical exercise of the professional athletes leads to activation of the important enzyme telomerase and stabilizes the telomere," said Ulrich Laufs, the study's lead author and professor of clinical and experimental medicine at Saarland University in Homburg, Germany.
"This is direct evidence of an anti-aging effect of physical exercise," Laufs said. "Physical exercise could prevent the aging of the cardiovascular system, reflecting this molecular principle."
In addition, the animal studies of Laufs and colleagues show that exercise exerts important cellular functions beyond the regulation of telomere length, such as protecting the cell from deterioration and programmed cell death.
In the clinical study, the researchers analyzed 32 young professional runners, average age 20, from the German National Team of Track and Field. They compared the young professional athletes with middle-aged athletes who had a history of continuous endurance exercise since their youth.
The two groups were evaluated against untrained athletes who were healthy nonsmokers, but who did not exercise regularly. They were matched for age with the professional athletes.
Long-term exercise training activates telomerase and reduces telomere shortening in human white blood cells, the researchers found. The age-dependent telomere loss was lower in the older athletes who had performed endurance exercising for several decades.
"Our data improves the molecular understanding of the protective effects of exercise on the vessel wall and underlines the potency of physical training in reducing the impact of age-related disease," Laufs said.
The study will be published in December in Circulation, a journal of the American Heart Association.