Why Runners Don’t Get Knee Arthritis

Education ResourcesA recent study published in Med Sci Sports Exercise (September 12, 2013 (Epub ahead of print) compared the forces that were generated (knee joint loads) while running to walking over the same distance in a small group of healthy adults. Although the peak load was three times higher in running, the relatively short duration of ground contact and relatively long length of strides in running were no higher than in walking in total per distance traveled.

The authors point out that runners do not have an especially high risk of knee OA compared to non-runners. Is this the reason why?

Walking is considered a low-impact activity and many physicians recommend walking for their older patients for both cardiovascular health and as a safer alternative to running. Previous studies had pointed out that running does not substantially increase the risk of developing hip arthritis and does not predict the future need for a total hip replacement. When compared to people who were less active, they had less overall risk of developing arthritis that people who were less active. However, until now, no one has compared the forces generated in an attempt to explain this paradox.

The primary author of the knee study says that their results are not an endorsement of running for knee health. Runners frequently succumb to knee injuries unrelated to arthritis, he said, and his study does not address or explain that situation. One such ailment is patellofemoral pain syndrome (runners’ knee).

These two studies leave many unanswered questions:

  • Did the weight (BMI) of the runners make a difference in their ultimate outcome in the real world (OA vs. no OA)?
  • Do runners with poor form/poor alignment stop running so there is a self selection process going on?
  • Is using the forces generated per distance measurement a legitimate way to look at forces generated over a lifetime of running and walking?
  • Does this study substantiate what you, the clinician, see in your practice? Or do you tend to see the “running failures” who due to faulty biomechanics or faulty genetics end up giving up on the attempt to be life-long runners? 
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One Response to Why Runners Don’t Get Knee Arthritis

  1. Kristen Suvick says:

    About me-I am a school based PT and a distance runner. I started running 4 years ago when I ran my first 5K. Prior to that I was active but not athletic. I never really participated in any team sport or regular exercise regimen. Since that first 5K I’ve run 6 marathons as well as many shorter distances from the mile to 13.1mi since but not without a large number of injuries. I started out with “runner’s knee” which was solved with PT and exercises to strengthen my quads and correct my tracking issue. Since then I have had 7 bone stress injuries(fracture or reactions) involving metatarsals, tibias and most recently a severe stress fracture of the neck of my femur that had me on a walker for 3 months. I’ve also frayed the labrum of my hip and had tendon strains and muscle tears. I am 5’5″ and weigh 115lbs. I am also quite competitive (aka fast) and have placed 9th in my age group (45-49) in the Boston marathon. I take multiple supplements including combining and appropriately timing my intake of Calcium and vitamin D, Iron and vitamin C, amongst others. I also work with a nutritionist to appropriately monitor and time intake of protein, carbs etc in relation to my workouts. I have had my gait analyzed by several PTs, coaches and trainers. I do have some minor flaws to my form. The impact of these flaws may be exaggerated by the number of miles and pace that I run, 25-70 miles per week depending on where I am in my training cycle. So maybe I’m not the average runner, however, I would have to say that running has put a great deal of stress, wear and tear on my body even though I get the best of advice and care during my training. My best guess is that I am not allowing my body enough recovery time between runs and I feel that this is pretty common especially in women my age and older runners in general. In my experience communicating daily online and in person with runners on a daily basis, they do have common injuries related to running, however, it seems that true joint issues are typically present from previous injury in their your that is exacerbated by running rather that running causing joint damage or injury. Many of “us” don’t seek help until we cannot run leading to more serious injuries and longer recovery. Are walkers the same or do they have less injuries? I would bet that overall for pure health benefit without injury that walking is a better alternative. There are many durable runners out there with healthy bones and soft tissues uninjured by running but there are many more who struggle with ongoing issues. However the ones I know who are injured don’t become couch potatoes. They are still by large a healthier fitter group than the average population. Therefore at least, I would say the risks outweigh the benefits of running.

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