I love it when new data challenges the conventional wisdom. And a truism that is often perpetuated without interrogation is that long distance running, particularly on the road, causes osteoarthritis of the knees, hips and possibly degeneration of the lumbar discs.
But is there any data to support these assertions?
A review by Cymet and Sinkov in the Journal of the American Osteopathic Association (1) highlights the lack of evidence to suggest that running is bad for your joints. Indeed, they suggest that, “the preponderance of data seems to indicate that moderate levels of running do not increase the risk of osteoarthritis of the knees and hips for healthy people and that this activity might even have a protective effect.” While this might sound somewhat contrary, it should be no surprise that connective tissues undergo a reactive hypertrophy when they are exposed to long-term repetitive loading, including articular cartilage. Chakravarty (2), after studying a group of runners over two decades, stated that, “Data suggest that long-distance running may not be associated with increased progression of knee OA in the absence of knee injury, obesity, proprioceptive deficit, or poor muscle tone.”
But what about other supposed running-related injuries such as calcaneal spurs, Achilles tendinopathy or plantar fasciitis?
There is a growing body of evidence to suggest that the rise of lower limb overuse injuries has paralleled so-called ‘advances’ in the design of running shoes. Prior to the 1970’s, and for most of our history, runners have either proceeded barefoot or used minimal footwear. But after the advent of the padded running shoe there has been a proportional rise in lower extremity injuries. According to Richards et al (3), “The use of cushioning in running shoes is based on the following assumptions: (1) that impact forces while running are a significant cause of injury, (2) that running on hard surfaces is a cause of high impact forces, (3) that a cushioned shoe can reduce impact forces to a less injurious level, and (4) that the potential of the cushioning itself to cause injury is minimal.” However, the evidence for this is very limited and certainly the prescription of modern running shoes is not ‘evidence-based’.
Unfortunately, thinking about running shoes over the past 40 years seems to have promoted an arms race, with the development of ever greater shoe complexity, but new thinking suggests that we have designed ourselves into a biomechanical corner.
In essence, the evidence suggests that our biologically normal running style has transformed from a predominantly fore-foot strike (or mid-foot strike) to a heel strike. And landing heavily upon your heel is not what nature intended, no matter how well padded it might be. Not only does landing upon your heel create greater impact forces upon the lower limb, the force actually increases with the amount of shoe padding provided.
As paradoxical as it sounds, there is now a growing consensus between biomechanists that the modern running shoe may well be the cause of many of our problems, as they increase ground reaction forces, limit proprioception, weaken the intrinsic muscles of the foot and reduce arch strength. This seems especially so for the PCECH (pronation control, elevated cushion heel) models.
Harvard professor Daniel Lieberman (4) has embraced his research findings by putting his money where his mouth is and taken up barefoot running. Take a look at the video below from the journal Nature.