Common sense tells us that running places a lot of stress on our joints, particularly the knees. We've all heard I'm sure that every time we take a stride whilst running we're placing '3 times our body weight' through our knee joints. Repeat this hundreds of times for each run, multiplied by many years and your knees are surely going to suffer?
But are they?
As skeptics, we shouldn't draw any conclusions until we've looked at the evidence. So what does the evidence actually say about running's effect on the knees?
Well as you can imagine because of the popularity of running, research on the subject is not lacking. That which has looked at the impact (no pun intended) of running from a muscular skeletal perspective has suggested, perhaps surprisingly, that running has little or no negative effect on the prevalence and/or development of knee issues.
A study published in the Archives of Internal Medicine in 2008 looked at disability and mortality of runners over a 21 year period. 284 runners and 156 controls who were 50 and over were followed during this period. At the end of the study it was found that the runners had a considerably lower mortality and disability rate as compared to the controls.
Ok, so it would seem runners live longer and suffer less from disability (that's a good start) but what about the knees specifically?
A 2008 study published in the American Journal of Preventative Medicine which looked at runners over an 18 year period concluded that runners did not have a higher incidence of knee osteoarthritis nor did they require more knee replacements than non runners.
Another study from 1995 compared the incidence of knee osteoarthritis in footballers (that's soccer players for non Europeans) weight lifters, runners and shooters (a sort of control group I guess). Weight lifters and footballers didn't fair too well I'm afraid, by which I mean they had a higher incidence of knee issues, where as runners and shooters (who are essentially sedentary) had the fewest.
An earlier study in 1990 published in the American Journal of Sports Medicine showed that formerly competitive runners did not have higher rates of arthritis in their hips, knees or ankles when compared to non runners.
To broaden things out a little an even earlier study in 1987 titled 'Aging, long-distance running, and the development of musculoskeletal disability' showed that runners had less physical disability, maintained more functional capacity, visited their doctor less (although 1/3 of their visits were about running related injuries!) and developed musculoskeletal disability slower than their control (non running) counter parts.
So as you can see the evidence would suggest strongly that running is not bad for your knees. I perhaps wouldn't go as far as saying that running is good for your knees but it certainly seems based on the evidence, that there are some positive benefits from a musculoskeletal and health perspective.
One caveat though; If you already have a knee problem, running is most definitely not good for your knees. The risk of knee osteoarthritis after suffering from knee joint injury is high. According to an article published in the journal Arthritis Research & Therapy, approximately 50% of people who've had an anterior cruciate ligament or meniscus tear develop knee osteoarthritis!
So to finish I'd say that if you're healthy and have no joint problems, carry on running to your hearts content. Without a doubt it's good for you. If on the other hand you've already got knee problems and you don't want to gamble their future health on the toss of a coin, you should probably hang up the running shoes and take up something a little less impactful; shooting maybe ;-) or perhaps cycling would be better!
Is running associated with degenerative joint disease? JAMA. 1986 Mar 7;255(9):1152-4.
Long Distance Running and Knee Osteoarthritis. AMERICAN JOURNAL OF PREVENTITIVE MEDICINE. August 2008 Volume 35, Issue 2, Pages 133–138
Reduced disability and mortality among aging runners: a 21-year longitudinal study. ARCHIVES OF INTERNAL MEDICINE. 2008 Aug 11;168(15):1638-46.
Knee osteoarthritis in former runners, soccer players, weight lifters, and shooters. ARTHRITIS AND RHEUMATISM 1995 Apr;38(4):539-46
Aging, long-distance running, and the development of musculoskeletal disability. A controlled study. AMERICAN JOURNAL OF MEDICINE. 1987 Apr;82(4):772-80
Long Distance Running and Knee Osteoarthritis A Prospective Study. THE AMERICAN JOURNAL OF PREVENTATIVE MEDICINE. 2008 Aug 35(2) 133-138.
Prevention of injury-related knee osteoarthritis: opportunities for the primary and secondary prevention of knee osteoarthritis. ARTHRITIS RESEARCH & THERAPY 2010 12:215
Long distance running and osteoarthrosis THE AMERICAN JOURNAL OF SPORTS MEDICINE. July 1 1990.
Does Running Cause Knee Osteoarthritis? CLINICAL CORRELATIONS The NYU Langone online Journal of Medicine. September 14, 2013