Is Running Bad for Your Knees?
Is running actually creating knee pain....?
We have all heard people claim that running is bad for your knees and that all that impact can lead to development of osteoarthritis and pain. Is there any basis for this traditional claim? Well, truth be told, there isn’t much. In fact, the prevalence of hip and knee osteoarthritis in recreational runners is 300% lower than in sedentary individuals.
Let’s look at the anatomy behind it all:
Osteoarthritis (OA) refers to aging of a joint. It occurs when the protective cartilage in the joint wears down over time. Cartilage is soft tissue that helps to reduce friction between two bones, allowing you to move more easily. OA a common side effect of aging and symptoms include joint pain, stiffness (especially in the morning), and swelling. There are different grades of OA:
Stage 1 refers to minor wear and tear, Stage 2 we maintain normal joint space with initial growth of bone deposits, Stage 3 the joint space is lessened moderately, and Stage 4 is the most severe on imaging, often resulting in joint replacement surgery.
Research has now shown that 40-50% of people 40 years of age and older have OA changes (not just in our knees) on X-ray but have NO pain. The sound research comparing characteristics of these asymptomatic individuals to those with pain gives us reason to think that running isn’t too bad after all.
How does running improve knee health?
In one research study, subjects started a 10-week running program and had an MRI before and after the program. Researchers noticed that for those who started running, there were actual changes in their cartilage after 10 weeks. They found higher concentrations of glycosaminoglycans (GAGs) in the cartilage, which are important molecules for physiological functions. By attracting water in the cartilage, GAGs can make the cartilage more tolerant to loading. So over the course of 10 weeks, these runners improved the loading capacity of their cartilage, just by stimulating it with impact.
A 2013 study by Hinterwimmer et. al. found that in beginner level marathon runners who performed a 6-month training program and a marathon run, there was no significant cartilage loss among the joints of the knee despite minimal decreases in cartilage volume and thickness on the lateral femur.
What does all this mean?
Well primarily, running does not wear out the cartilage in your knees. But there’s a slight caveat to that statement. In a study looking at changes on x-ray for hip and knee OA, researchers found that competitive (international or world class) runners had a 13.3% prevalence of OA, which was more than non-runners and sedentary people (10.2% prevalence). Recreational runners had only a 3.5% prevalence. So it appears that too much of a good thing can be, well… not as good. That’s not too surprising. But for recreational runners (even running up to 40-50 miles a week), you can reverse aging effects of the knee joint.
How to safely run with OA
We know that running is safe for those who have grade 1 or 2 knee OA. Based on current literature, running does not progress knee OA in people who run. If running isn’t painful, you can continue to run, even if you have OA findings on imaging. For those with mild OA, it is normal to feel some mild discomfort in the joint when you run, as long as symptoms return to baseline within the hour after you stop. In addition, there should not be any increase in stiffness or swelling the day after.
If you are symptomatic, it’s important to consider load when planning your runs. Instead of long duration and less frequency, consider shorter but more frequent runs to reduce peak load and magnitude. It is better to distribute the load across more sessions so there is less load at a given time for the joint.
For example, instead of 3 x 60-minute runs a week, try running 5-6x a week for 20-30 minutes each run. Running twice in the same day can also be helpful. You still get the adaptations but you’re staying under the body’s load threshold.
The new trends footwear nowadays is either full cushion or zero drop! Shoe companies claim that these maximally cushioned shoes take lots of force and load off the body or that your body alignment will be best with a certain shoe. A common myth within the running world is that by putting more cushioning under the foot, you decrease the impact forces and load through your joints. HOWEVER, it’s actually the opposite. Impact and loading (particularly at the knees) INCREASES in highly cushioned shoes.
Consider how your body reacts when running barefoot on concrete vs running on sand or a trampoline. We must stiffen up our bodies in response to more unstable surfaces, as opposed to landing softer on harder surfaces . Shoes change the way people run; therefore, the more cushioning, the higher the stack height, and the farther your foot is off the ground. If you cannot feel the ground under your foot because you have so much cushioning, you will inevitably land with a stiffer, harder leg. You won’t necessarily feel it with each step, but over time the load applied through the knee joint will be much greater than it would be with a neutral shoe.
You can’t afford to NOT run for the health of your joints across your lifespan. Healthy loading stimulates positive adaptations, not only for your musculoskeletal system, but for every system in your body. If you’re running with OA, consider spreading out your runs so each one is shorter, but you’re running more frequently. In terms of what type of footwear is best, it’s also important to consider the shoe’s level of cushioning and your foot type. A highly cushioned shoe may not be the best choice to reduce excessive impact forces through a knee that has limited loading capabilities. And a shoe a friend suggests isn’t always the answer. Find that glass slipper that is individual to you.
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