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The Impact of Running: It’s Not So Much on Your Knees

icing knee pain

Running can sure be a pain.
Photo credit: Heather Neal

No one seems surprised when I tell them I have a knee injury from running when they see me hobbling along during a flare-up. “Running will kill your knees you know!” they say with an eye roll and all the wisdom in the world. “Run now and you won’t be able to walk later.” None of those comments come as a surprise to me anymore. Since badly injuring my knee in the middle of a marathon relay several years ago, I’ve been told relentlessly to give up running. “Just walk,” my sports doctors have told me. “It’s much less impact on your knees. You’ll thank me when you get old.” Everyone seems to know that running will inevitably lead to bad knees, especially in the form of knee arthritis. But while everyone tends to believe that (and tell you that), it also looks like they’re wrong. (Thank goodness, because hurting my knee once has made me forever fearful of causing more permanent damage.)

Rearchers and doctors know the truth: that most runners don’t end up with arthritic knees. In fact, marathon runners often have a smaller risk of developing arthritis, according to a study in Medicine & Science in Sports & Exercise. They didn’t really understand the “why” part until recently though. A new study at Queens University in Ontario looked at the impact of running on the body. They compared it to the impact of walking, which is usually the low impact alternative given for running. Interestingly enough, they found that the overall impact on your knees from running and walking was about the same. While running no doubt exerts more force on your body and joints with each step than walking does, you also take fewer steps and remain on your feet for less time when running. The longer stride and quicker foot turnover of running makes up for the extra impact with each step, making it essentially equivalent to the impact you experience when walking the same distance.

Researchers were able to measure these amounts of impact by having volunteers walk on a special track while wearing reflectors to capture movement and force. I got to see one of these track set ups when I visited the adidas headquarters earlier this year and I have to admit it was pretty freaking cool to see all the data they can collect about what’s happening to your body during exercise and all the different things that affect it.

Because the force your body encounters while running and walking are nearly the same, it doesn’t make sense that running would cause knee arthritis and walking wouldn’t —which it doesn’t. One of the researchers from the study even speculates that running could actually help arthritis based on the type of resistance put on the joints and surrounding cartilege. (This part hasn’t been researched yet though.) Arthritis may sound like just a nagging pain (pun intended), but at this point, arthritis is incurable. Knowing running and exercise could help prevent or at least minimize arthritis is reassuring for those that aren’t ready to be couch-bound.

Previous studies have verified the same thing: that the impact of running itself doesn’t damage your knees. A study a decade ago took MRIs of marathoners’ knees 10 years apart. The only cartilage damage found was in an individual that quit running between the two exams. Intriguing.

Other ways to help prevent or ease the pain and damage of arthritis include staying slim so there’s less weight on your joints, exercising in the water (the added bouncy is beneficial), and maintaining an active lifestyle.

Now this doesn’t mean running won’t give you bad knees all together; it means it probably won’t cause arthritis. Plenty of runners, like myself, still suffer from debilitating knee injuries like patellofemoral pain syndrome and ilitotibial band friction syndrome. For injuries like these, walking does seem to cause less pain, but perhaps it’s because of the mechanics and not just the amount of impact. So while this means I’m still stuck with my current knee injury, at least I can be comfortable knowing that I won’t end up with arthritis just because I like to run. Unfortunately I’m not completely off the hook though because it’s thought that when runners do get knee arthritis, it tends to come after a disruption in activity —like when you’re recovery from an injury. Your joints may get used to the motion of running, thereby not causing damage, but when you stop and start again that “path” gets disrupted and opens the door for damage. It seems like us injured runners just can’t win.

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