Key Points:
- There?s a common belief that running leads eventually to arthritis in the hips or knees but evidence shows that runners have no increased risk for arthritis and in fact may have lower risk than the general population
- The biggest risk factors for developing arthritis are prior injury or surgery to the joint, family history, and high body mass index
I see a lot of folks in my clinical practice with hip and knee arthritis and many of them have extensive running histories. Most of?these folks believe that it?s the long term running that eventually led to the arthritis, but the belief that running causes knee arthritis is probably a myth.
The idea that running can lead to arthritis makes sense. You run on a hard surface for long distances and over many years the impact leads to wear and tear. Seems pretty logical, right? Well the available evidence points us in a different direction.
There have been several good quality medical studies done over the years to study the relationship between running and arthritis. I want to highlight three that have some interesting and relevant points.
This study published earlier this year?specifically studied marathon runners. These were experienced high mileage runners, average age 48 years, typically training about 36 miles per week. They?d completed an average of 76 marathons! About 47% reported hip or knee pain but only about 9% had arthritis. The strongest predictors of hip or knee arthritis were older age, family history of arthritis, and any prior surgery on the joint. But marathon running itself was not predictive of arthritis.
This study of about 75,000 runnersis pretty impressive for the number of people who participated. It?s incredibly difficult to get information on that many individuals. The author used the National Runners? Health Study and the National Walkers? Health Study. During a multi year follow up, about 2.6% of the runners reported arthritis, and about 4.7% of the walkers reported arthritis. These are pretty low numbers since the generally accepted prevalence of arthritis amongst all U.S. adults over 55 years of age is about 18%. The author believed that the most meaningful reason is that the body mass index (BMI) of the runners was less than the walkers, and presumably both are lower than the average BMI for the general population.
And here?s another interesting study titled??Why Don?t Most Runners Get Knee Osteoarthritis??These authors used motion capture imaging and force plates in the ground to estimate forces across the knee joint with running and walking. They found as expected that there?s quite a bit more load across the knee joint with running (8x body weight) vs. walking (3x body weight). But the runners have longer stride lengths than the walkers, which meant that they took fewer steps over a given distance than walkers and had fewer impacts. The runners also experienced any pounding for a shorter period of time than when they walked, because their foot was in contact with the ground only briefly with each stride.
The net effect was that the amount of force moving through a participant?s knees over any given distance was equivalent, whether they ran or walked. It?s an interesting mechanical explanation.
So these and other available scientific evidence indicate that running itself is not a risk factor for developing hip or knee arthritis. The strongest risk factors appear to be prior surgery or injury to the joint, a family history of arthritis, and a high BMI. If you start out running with a healthy joint there?s good reason to believe you can run healthy for many years. This myth is probably busted.
Click here for full podcast playlist.
