Men who get plenty of aerobic exercise may delay the onset of age-related high cholesterol, potentially lowering their risk for heart disease, a new study suggests.

Researchers followed thousands of men over several decades, periodically drawing blood to test their cholesterol and then making them run on treadmills to measure their cardiorespiratory fitness. Men who could run longer and faster – signs that their bodies more easily deliver oxygen to muscles – also had lower cholesterol.

"The benefits of physical fitness in improving cholesterol levels are greatest in young to middle-age adults and tend to decrease gradually with older age," said Dr. Usman Baber, a cardiovascular researcher at the Icahn School of Medicine at Mount Sinai in New York City.

"These findings should reinforce the importance of young to middle-age men incorporating regular aerobic exercise as part of a healthy lifestyle," Baber, co-author of an editorial accompanying the study in the Journal of the American College of Cardiology, said in an email to Reuters Health.

To understand the link between fitness and cholesterol levels, researchers studied data collected for 11,418 men between 1970 and 2006 at a clinic in Dallas. Most participants were white, college-educated and relatively well off financially.

Men were excluded from the analysis if they had a history of heart attack, stroke or cancer at any point during the study period, or if they reported having elevated cholesterol or triglycerides during clinic visits.

On average, each man had at least three exams testing cholesterol and fitness levels.

The better men did on fitness tests, the more likely they were to have lower total cholesterol, as well as lower levels of what's known as low-density lipoprotein (LDL), the bad kind of cholesterol that builds up in blood vessels and can lead to atherosclerosis, blood clots and heart attacks.

Fitter men also had higher levels of so-called high-density lipoprotein (HDL), the good cholesterol that helps purge the bloodstream of LDL.

Men with higher cardiorespiratory fitness levels had better cholesterol profiles than less fit men from their early 20s until at least their early 60s, though the difference diminished with older age.

At the same time, men with lower fitness levels reached abnormal cholesterol levels before age 40.

One limitation of the study is that it lacked data on cholesterol-lowering medications and didn't track changes in eating habits that might impact cholesterol, the researchers acknowledge. There was also limited data for the oldest men in the study.

Even so, the current study adds to a growing body of evidence supporting the benefits of lifelong physical activity in preventing diseases that tend to develop with age, said Dr. Paola Boffetta, a researcher at the Icahn School of Medicine at Mount Sinai and co-author of the editorial.

"There is very strong evidence that being active is beneficial throughout life not only for cardiovascular disease but for a very large number of chronic diseases and for osteoporosis and fractures," Boffetta told Reuters Health.

To achieve the fitness levels necessary to ward off age-related high cholesterol, men should get 150 minutes a week of moderate activity or 75 minutes of vigorous activity, said study co-author Dr. Xuemei Sui, a researcher in exercise science at the Arnold School of Public Health at the University of South Carolina. These activities might include walking, running, swimming or cycling.

"It does not matter how old men are when they exercise; they can benefit at any stage," Sui said in an email. "Of course, the younger they start exercise, the later the onset of high cholesterol, especially before 60 years old when cholesterol tends to increase with aging."