A new study shows that running regularly can help people live significantly longer and have a better quality of life.

Alan Lubell, 69, says he has felt the benefits of running three or four days a week for 40 years.

"When I get my checkups every year, usually my blood pressure is low, and my health is very good," Lubell said.

Stanford University researchers got similar results in a study that tracked runners for more than 20 years. They found that elderly runners had fewer disabilities, led a more active lifestyle and were half as likely to die early.

Aerobic exercise, such as running, can strengthen the heart, muscles and bones and protect the brain, said Dr. Mark Klion, an orthopedic surgeon and a triathlete.

"I think that, all wrapped up into one, will definitely increase your life expectancy," said Klion, with the Mt. Sinai Medical Center in New York City.

Many experts believe that a lot of exercise will do more harm than good for elderly people. In particular, they believe exercise could cause more orthopedic injuries.

Study researchers, however, said that their work disputes those claims and indicates that runners do not need more knee replacements.

"Maintaining that active lifestyle helps protect those joints," Klion said.

The study found that running reduced cardiovascular deaths and is associated with fewer early deaths from cancer, neurological disease and infections.

For those who are unable to run, walking is still good for the heart. Experts recommended walking for 30 minutes five days a week and aiming to achieve a 15-minute mile.

"I see no reason why I should stop. I can still run. I feel good," Lubell said.