Is Running Bad For Your Knees

You’ve probably heard people claim that running is bad for your knees, that all that impact can lead to early development of osteoarthritis. 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.

A quick anatomy lesson:

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 (like graying hair or wrinkles). 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, while Stage 4 is the most severe on imaging, often resulting in a joint replacement surgery.

Research has shown that 40-50% of people 40 years of age and older have OA changes on X-ray but have NO pain. There’s also a lot of research out there comparing characteristics of these asymptomatic individuals to those with pain. Why do some individuals with OA have pain, and some do not?

How does running improve knee health?

In one research study, subjects started a 10-week running program. They 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 2019 study by Horga et.al found that training for and running a marathon can also improve different features in the knee. Results showed that there was reversibility in the damaged subchondral bone of the tibia and femur in novice runners after training for and running a marathon.

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 something mild 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.

Footwear considerations

The new trend in footwear these days is cushion cushion cushion! Shoes companies claim that these maximally cushioned shoes take lots of force and load off the body. Most of you may also believe 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 (go ahead, try it and compare). We must stiffen up our bodies in response to more unstable surfaces, as opposed to landing softer on harder surfaces (try to land with a stiff leg on concrete… ouch!). Shoes change the way people run. 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.

In Conclusion

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 shoe’s level of cushioning. A highly cushioned shoe may not be the best choice to reduce excessive impact forces through a knee that has limited loading capabilities.

References:
Alentorn-Geli E, Samuelsson K, Musahl V, et al. The association of recreational and competitive running with hip and knee osteoarthritis: a systematic review and meta-analysis. Journal of Orthopaedic & Sports Physical Therapy.2017;47(6):c373-390.

Davis IS, Rice HM, Wearing SC. Why forefoot striking in minimal shoes might positively change the course of running injuries. J Sport Health Sci. 2017;6(2):154-161.

Davis, IS. Shifting paradigms in the approach to footstrikes, footwear and treatment of the foot. J Foot Ankle Res. 2011;4. 1-1. 10.1186/1757-1146-4-S1-A3.

Horga LM, Henckel J, Fotiadou A, et al. Can marathon running improve knee damage of middle-aged adults? A prospective cohort study. BMJ Open Sport Exerc Med. 2019;5(1):e000586.

Laskowski ER, Newcomer-Aney K, Smith J. Refining rehabilitation with proprioception training: expediting return to play. The Physician and Sports Medicine. 1997;25(10).

Riva D, Bianchi R, Rocca F, Mamo C. Proprioceptive Training and Injury Prevention in a Professional Men's Basketball Team: A Six-Year Prospective Study. J Strength Cond Res. 2016;30(2):461-475.