A new study comes to the somewhat counterintuitive conclusion that marathon runners have less arthritis than non-runners.

The study

Most people would assume that serious runners face a high risk for arthritis of the hip and knees. Yet prior research has generally failed to uncover such a connection. The most recent study, published in the Journal of Bone and Joint Surgery, actually found that veteran American marathoners had only half as much arthritis as non-runners. According to alarming new data from the Centers for Disease Control and Prevention, arthritis now represents a $300 billion annual burden.

Method and results

Researchers from the orthopedic department at Philadelphia’s Thomas Jefferson University compared arthritis rates between 430 U.S. marathoners and a matched sample of non-runners in the National Center for Health Statistics database.

The marathoners (average age 46, and 51 percent women) had been running for an average of 19 years, logging 35 miles a week, and finishing 48 marathons. Despite this, they had an arthritis prevalence of 8.8 percent vs. 17.9 percent for non-runners. Aging past 65 did increase the marathoners’ arthritis rate — to 24.5 percent. But this was still roughly half the 49.6 percent of non-runners older than 65.

The team from Thomas Jefferson believes marathoners and other runners may gain arthritis protection from muscle development, body weight control, decreased levels of inflammatory agents and the well-known bone strengthening that follows moderate-impact sports.

Recommended action

If you’re running healthy, stay the course, advises Thomas Jefferson orthopedist Danielle Ponzio. If you’re thinking about beginning a running program but are concerned about arthritis, don’t worry. Just begin slowly and progress moderately. “Running is not harmful to healthy hips and knees,” Ponzio says. “In fact, it promotes joint and general health.” Those runners who do develop arthritis often get it after earlier injury or surgery, or from family genetics.

Amby Burfoot is a freelance writer and editor and a member of the Running Hall of Fame. His most recent book is “Run Forever: Your Complete Guide to Healthy Lifetime Running.”

More from Lifestyle: