There’s been some buzz about a new study that explains why runner’s don’t get osteoarthritis (OA).
But the article, especially the headline, in the NY Times is misleading.
Runner’s certainly are not immune to OA. But if you’re healthy (so that means ideal body fat levels for age and gender among other things) AND have been running a long time consistently, you have NO GREATER risk of developing OA than the general population.
But that’s not saying a lot.
Over 50% of people by age 65 have OA and over 80% will have radiographic evidence of the disease.
This study examined “load per unit of distance traveled” (PUD) in “14 healthy adult recreational runners, half of them women, with no history of knee problems”. The PUD is the total force over a unit of time. What the study found was that when you compare running and walking total forces over the same time period, the forces are about the same. The reason is that with running, although the force is several times your bodyweight, your foot is on the ground for a fraction of the time that it is on the ground while walking.
It’s just math. But the authors gave the impression that the PUD was the reason that runners seem to not develop OA at any greater frequency than the general population but that may or may not be the explanation. To reach a conclusion that suggests the PUD loads are the same therefore that’s why runners don’t develop OA is a stretch. Maybe the reason is that healthy runners are, well, healthier than the general public and the issue about joint loads is more about the health of your knee joint and the loads it can withstand as opposed to just the loads themselves.
The other problem is that prior studies have demonstrated that runners who are at no greater risk for knee OA are healthy and have been running for a long time. And this study was not a comparison study; it’s a biomechanics study.
This study DOES NOT suggest that if you decide to take up running having never run before, with a prior history of knee trouble, and in generally less than optimal physical condition, that your risk of OA is no greater than anyone else.
The take away is this. If you want to reduce your chances of getting OA, improve your overall health and fitness but do so with respect for your joints. Don’t just start running thinking that running will inoculate you against knee OA.