Running and other forms of vigorous exercise may prevent some of the aches and pains that come with age, a new study suggests.

Researchers found that among nearly 900 adults age 50 and up, those who regularly exercised were less likely to develop painful joints and muscles over the next 14 years. Throughout the study period, active adults' pain-rating scores were consistently 25 percent lower than their peers'.

This was despite the fact that active men and women were more likely to have a history of bone fracture.

On the other hand, their sedentary peers had a higher rate of arthritis, which may help explain the findings, according to lead study author Dr. Bonnie Bruce of Stanford University in Palo Alto, California.

It's also possible, she stated, that active adults' lower risk of pain reflected their greater "musculoskeletal reserve" or the effects of endorphins, natural pain-killing chemicals released by the brain during prolonged exercise.

But the exact mechanism by which regular exercise may ward off chronic pain is not yet clear, Bruce and her colleagues report in the journal Arthritis Research & Therapy.

Their study included 866 healthy adults who were at least 50 years old, more than half of whom were members of a runners' club. At the start of the study and annually thereafter, all participants reported the amount of time per week they devoted to vigorous exercise, such as running, swimming, brisk walking, biking and aerobics. They also used a pain-rating scale to describe any pain or stiffness they'd suffered during the past week. [

On average, participants' exercise levels at the end of the 14-year study remained similar to what they were at the outset.

Not surprisingly, runners' club members spent more time sweating -- logging an average of 5 hours of exercise per week, versus 2 hours among the other study participants. They also tended to be younger and leaner, but even when the researchers factored in weight and other differences, greater activity was related to less pain over time.

Not everyone, of course, is going to join a runners' club to lessen their risk of pain. However, Bruce pointed out, the study measured a variety of activities besides running, and many previous studies have illustrated the overall health benefits of more-moderate exercise.

SOURCE: Arthritis Research & Therapy, September 19, 2005.