Osteoarthritis and Running
Osteoarthritis (OA) occurs when the cartilage lining the bone surface wears away. At its worst, OA leads to bone on bone contact, with debilitating pain that may eventually result in a joint replacement. While symptoms do not always correlate with disease progression, over 27 million individuals in the US are affected, with more than 7 million having received a joint replacement. OA is multifactorial, and sports participation, frequent squatting, previous injury, obesity, muscle weakness, genetics and old age are associated with an increased risk of knee OA in particular.
Running and Osteoarthritis
Mechanical forces exerted on weight bearing joints are a known risk factor for OA, leading many to wonder: does running cause OA? While the evidence is conflicting, most studies indicate that running is not associated with an increased prevalence of OA. In fact, in a retrospective analysis by Williams, recreational runners were found to have a decreased risk of hip OA and hip replacement, which the researchers associate with the runners’ lower BMIs. Indeed, running may be protective against OA.
Many studies have examined the effect of moderate running on OA progression, so what about high level athletics participation? In a systematic review, Driban et al. examined the risk of developing knee OA as a result of sport participation. They found an increase in knee OA prevalence in soccer, elite-level long-distance running, competitive weight lifting, and wrestling athletes.
The Bottom Line
In other words, there appears to be a dose-dependent relationship between OA and activity level. This parallels conclusions made from research in animal models, namely that some amount of loading is crucial for bone and cartilage health, but too much can be detrimental.
Why is running ok?
Contact forces in running are certainly higher than in walking, but Miller et al. argue that runners do not have an especially high risk for OA due to the relatively short duration of contact with the ground and relatively long length of strides. The peak load is higher in runners, but the short amount of time spent in a loaded position seems to blunt this effect.
Running has additional benefits of increased bone density and weight control, but also a long and tumultuous history of overuse injuries. Up to 70% of runners get injured in a given year, and a history of injury—acute or overuse—can accelerate OA.
