Mechanism of Exercise-Related Longevity Uncovered

October 16, 2007
Wayne Kuznar

Internal Medicine World Report, October 2007, Volume 0, Issue 0

Unparalleled CV Benefits Not Limited to Athletes

Unparalleled CV Benefits Not Limited to Athletes

By Wayne Kuznar

VIENNA, Austria—Improved coronary and peripheral blood flow, enhanced nitric oxide production, and the recruitment of bone marrow cells to the endothelium are among recently discovered mechanisms by which exercise training improves survival in both healthy individuals and those with cardiovascular (CV) disease, said experts at the European Society of Cardiology annual meeting.

N Engl J Med.

Regular exercise training is unparalleled in its ability to reduce CV risk, said Viviane Conraads, MD, PhD. Citing an old observational study ( 1986;314:605-613) that involved almost 17,000 men, she noted that those who expended >2000 kcal/wk on exercise had a 25% to 33% reduction in mortality during 12 to 16 months of follow-up compared with less-active men.

"I challenge you to go through the literature and find any intervention that gives this result," said Dr Conraads, professor in the Department of Cardiology, University Hospital Antwerp, Belgium.

N Engl J Med.

More recently, a 2002 study demonstrated that among 6200 men referred for exercise testing, exercise capacity was independently predictive of mortality ( 2002;346:793-810). When men were placed into quintiles based on their exercise capacity, the largest reduction in mortality was observed between the least fit men and the men in the next quintile of fitness, "Suggesting that even a limited improvement in fitness has significant results," she said. "You don't have to be an athlete to profit from exercise."

Viviane Conraads, MD, PhD

How does exercise work to increase longevity? One mechanism is an increase in nitric oxide production by exercise training. Endothelial nitric oxide synthase increases in concentration with activity, leading to an increased production of nitric oxide. In addition, exercise reduces the amount of reactive oxygen species that is known to inactivate nitric oxide.

Circulation.

Exercise may also repair the endothelial layer through mobilization and integration of endothelial progenitor cells, which are derived from bone marrow stem cells. "These cells go to the injured endothelium and replace damaged endothelial cells," said Dr Conraads. In patients with peripheral arterial disease or coronary artery disease, 4 weeks of exercise training significantly increased the number of circulating endothelial progenitor cells and the ability of these cells to integrate into the vascular networks ( 2005;111:3391-3399). "The effect is very rapid but disappears rapidly," she said, in emphasizing the importance of continued training.

Finally, exercise can improve blood flow, not only to working muscles but also to the heart.

Most of the benefit is from classic aerobic (endurance) exercise, she said. Recent evidence shows that interval training produces a rapid gain in exercise capacity.

For those participating in competitive sports, preparticipation screening to identify those at increased cardiac risk is wise, said Domenico Corrado, MD, PhD, professor of cardiovascular medicine, Division of Cardiology, University of Padova Medical School, Italy. He cited the increased risk of sudden cardiac death in athletes versus nonathletes. In athletes with underlying CV disease, mainly cardiomyopathy, vigorous activity may act as a trigger for the occurrence of ventricular arrhythmias.

N Engl J Med.

In a study of sudden deaths in Italian athletes and nonathletes aged ≤35 years ( 1998;339:364-369), the most common causes of the 49 sudden deaths in athletes were arrhythmogenic right ventricular cardiomyopathy (22.4%) and coronary atherosclerosis (18.4%).