Does Running Really Ruin Your Knees?

Many life-long runners come to my clinic with knee pain and arthritis, and they ruefully blame their beloved running.  But is running, and in particular marathon running, really responsible for untoward wear and tear on the knees? 

In several radiology studies from nearly twenty years ago, investigators tried to identify signs of joint stress in runners pre- and post-marathon.  In one study (Krampla et al, Skeletal Radiol, 2001), 8 recreational runners had knee MRIs prior to the Vienna City Marathon and then again 6-8 weeks after the race.  Six of the 8 runners had no acute or chronic negative effects detected on MRI.  One runner had acute changes that did not persist, and the single runner in the study who did exhibit signs of progressive arthritis had a pre-existing meniscal tear.  

In a similar study several years later (Hohmann et al, Am J Sports Med, 2004), six recreational and two semi-professional runners underwent both hip and knee MRI before and immediately after a marathon.  None of the runners exhibited bone swelling, inflammation of the bone lining, or fluid in the knee post-race except for one runner who had had ACL reconstruction 18 months prior to the race. Both groups of investigators concluded that marathon running had not caused undue harm to the joints of their study subjects.

A number of recent articles have employed either meta-analysis, which combines the results of multiple scientific studies, or systematic review, which critically analyzes multiple research studies, in order to address the question of whether the supposed link between knee osteoarthritis and running is truth or myth.  Tran et al (BJSM 2016) did not find a statistically significant relationship between osteoarthritis and long distance or middle distance running on both the elite and non-elite level.  Alentom-Geli et al (JOSPT 2017) analyzed 17 studies, which included a total of 114,829 runners, and found the overall prevalence of hip and knee osteoarthritis was 13.3% in competitive runners, 3.5% in recreational runners, and 10.2% in controls (ie, non –runners).  At least in this study, being a recreational runner provided a distinct advantage in terms of joint osteoarthritis, as did a history of running for 15 years or less. 

Published results from the Osteoarthritis Initiative, a retrospective, cross-sectional study, demonstrated no increased risk of radiographic evidence of osteoarthritis (ie x-ray findings), pain or other symptoms of disease in runners versus non-runners (Lo et al, Arthritis Care Res, 2017).  The authors concluded that in runners without osteoarthritis at baseline, running is not harmful to the knees.  Ponzio et al. (J Bone Joint Surg Am, 2018), in a longitudinal study of Masters marathoners, found a significantly lower prevalence of osteoarthritis in the study group when compared to matched non-marathoner adult controls.  Furthermore, the investigators found no significant increased risk associated with running duration, intensity, mileage or number of marathons completed. 

How might running be protective against knee osteoarthritis?  One author (Miller, Exerc Sport Sci Rev, 2017) has proposed that running actually conditions cartilage to withstand the mechanical stresses it imposes.  Another group (Hyldahl et al, Eur J Appl Physiol 2016) studied six recreational runners completing a running trial and found lower levels of pro-inflammatory mediators in joint fluid sampled from the runners after their running trial.  Furthermore, running seemed to promote the turnover of cartilage-specific proteins from joint fluid to the serum in the runners tested; a finding which indicated a beneficial effect of running on the knee joint.  Runners may also have body characteristics that protect against osteoarthritis, such as lower weight and body mass index (Williams et al, MSSE, 2013).

Not all studies cast running in such a positive light in regard to risk for knee osteoarthritis.  Another systematic review and meta-analysis (Timmins et al, Am J Sports Med, 2017) examined 15 studies and had mixed results.  The only consistent finding was that runners did seem to have a lower likelihood of having surgery due to osteoarthritis.  The authors concluded that future studies, designed specifically to ask this question in a prospective way, rather than pooling data or looking back over time, are needed to better characterize the relationship between running and osteoarthritis. 

In my view, most of the evidence argues against the accusation that long-distance running will ruin your knees.  I also feel the physical and mental benefits of our sport balance out the risks posed by the long-term wear and tear we experience when we run, day in and day out.  So, I hope I’ve given you fodder for some good comebacks when faced with negative comments about the effect of running on your knees.  Happy running this holiday season, and best wishes to you all for the New Year!