Osteoarthritis is usually not a mechanical wear and tear process. If you have osteoarthritis, exercise will not wear out your knee joints faster — quite the opposite. Therapeutic exercise has been proven to relieve the pain of mild knee arthritis and does not harm the cartilage.  This post will dive deep into the science to support why we should start to exercise to improve knee pain associated with osteoarthritis.  

For those of you who prefer a podcast format, here you go.  

How many of you have been told to rest and stop running or exercising because you have knee arthritis? Far too many people believe that arthritis is caused by mechanical wear and tear. It’s only natural that you might assume that your arthritic knee pain will worsen with exercise.    Too many health care professionals counsel their patients to stop running, speed walking, elliptical, treadmill, etc. to “save” their joints. Most of the time, you need to do just the opposite. The research over the years has been unequivocal.

Running may improve cartilage nutrition

Exercise has been proven to be the most effective treatment for early and moderate osteoarthritis of our joints. Exercise improves all-cause mortality and decreases your risks associated with muscle loss, frailty, sarcopenia, and so on. We are going to walk through the current research and evidence-based recommendations for the management of arthritic knee pain. 

Exercise improve arthritis pain

What are the causes of osteoarthritis of the knee?

There are many potential causes of osteoarthritis of the knee. In people without prior injuries osteoarthritis is usually a biologically mediated inflammatory process…. what does that mean?!?  
In our joints, we have 100s of proteins, cytokines, chemicals, and other compounds which are made by the synovium, or the lining of the knee joint. When our joints are healthy, the chemicals in our joint support cartilage health and nutrition.

Whether it is due to injury, or our metabolism, weight, and diet — a switch flips. Changes occur in our knee joint that is similar to the changes associated with other chronic disease states. That switch turns on genes in our DNA that increase the production chemicals that are hostile to the health of our cartilage. So over time, an increase in those unfriendly chemicals eventually cause cartilage cell injury. That weakens the cartilage and its ability to withstand stress.

If the cartilage is not functioning well, or if it becomes thinner, it can lead to pain, inflammation, warmth, and swelling. Osteoarthritis appears to be caused by low-grade chronic inflammation.  This is the same chronic inflammation held as a cause of other chronic diseases such as Type 2 diabetes, heart disease, and fatty liver. Much of the chronic disease burden that affects us appears to have a metabolic etiology or cause.  A few months ago, we discussed the issue of metabolic health and its impact on our health in this post.   We also discussed how chronic inflammation could lead to diseases, including dementia and heart disease

inflammation and knee arthritis
Attribution:https://www.sciencedirect.com/science/article/pii/S1063458414012801

 

Researchers are determining how all these proteins and substances in our knee joint affect cartilage health and the incidence of osteoarthritis.  Exercise has been proven to decrease the concentration of proteins and compounds in our knees that are hostile to cartilage health.  In this study, IL-10, a cartilage protective chemical in the knee, was produced in response to exercise.  Also, the concentration of a compound called COMP decreased within the knee with exercise.  COMP is a protein that is felt to be a biomarker of cartilage degeneration. This study shows that COMP levels in the blood increase during exercise but quickly return to baseline.  The increase in COMP in the blood does not seem to reflect a negative effect on an arthritic knee. 

Exercising with knee osteoarthritis is OK

 

Other research studies show that the concentration of COMP within the knee decreases with exercise.  Therefore, exercise might cause the COMP within the knee to be pushed into the bloodstream, or lymphatic system with activity.  Decreased COMP within in the knee, combined with an increase in the concentration of Interleukin-10 appears to show that exercise is not harmful to cartilage, and may be beneficial.  This research shows that running was associated with a decrease in the cytokines or the chemicals in the knee related to cartilage wear and degradation.  

Yes, there are mechanical causes of osteoarthritis. People with severely bowed knees or knock knees are more prone to developing arthritis. That’s because you are overloading one side of the knee joint if your knee is mal-aligned.  If you had a meniscus removed because of a tear, you are also at an increased risk of developing osteoarthritis.  Certain fractures or broken bones that involve the knee joint can lead to post-traumatic osteoarthritis.  Post-traumatic arthritis is rare, and it is due to the injury subsequent mal-alignment after the fracture heals. 

knee arthritis treatment
Copyright Medical Media Group.

What are the symptoms of knee arthritis? 

The symptoms of arthritis of the knee can vary significantly.  With mild arthritis, many people will have an ache associated with walking, stairs, or running.  The location of the ache or pain can be on the inner side of your knee, the outer side, or even in the back of the knee.  Osteoarthritis in some people will produce swelling, or what is commonly referred to as “water on the knee.”  Therefore some of you may have swelling of the knee while others will not.  Depending on the location of arthritis within your knee, it can feel like it wants to give way. A feeling of griding or “crepitus” is a common complaint.  When the inflammation due to the arthritis increases, you may have pain in the knee at night.  That’s why you may reach for a pillow to put between your knees when you sleep. Morning stiffness of the knee,  or stiffness if you have been sitting for a while is a common complaint if you have inflammation associated with knee joint cartilage degeneration.  

Xrays and Knee Arthritis  

The cause of osteoarthritis of the knee is not entirely clear.  Very different clinical pictures emerge when we see people in our offices and clinics.  Some of you have mild arthritis that does not bother you much. Arthritis might progress or worsen slowly over decades, or it might progress more rapidly.  In some, the pain you have might be minimal, and in others, the pain might be severe, regardless of how your X-rays look.  That means that we have some patients with mild arthritis on an Xray, but they have severe pain and swelling.  Others might have only a little pain despite X-rays that show severe arthritic changes.  

Metabolic Health and Knee Arthritis

The burden of osteoarthritis has been increasing across the globe.  This is similar to the increase in chronic diseases such as dementia, high blood pressure, Type 2 Diabetes, and heart disease. All of the tissues in our body, including our cartilage, are sensitive to our dietary intake.  Metabolic issues are felt to have a causative role in the development of osteoarthritis and other chronic disease states.  The earlier in our life that we realize this, the better off we will be. 

This post goes into more detail about the effect of our diet on our joint health and overall health.  What might cause those genes in our DNA to become active? Good question… It may be coded in your DNA. So if your parents have osteoarthritis your risk for getting it is higher. Like other chronic diseases you have heard me talk about, OA is similar in that it may be caused by poor metabolic health. It may also have been caused by an injury which occurred 20 years ago. One bleeding episode in the knee can initiate the process. Surgery can start an arthritic process too. Having a meniscus tear, and certainly having that tear removed compounds the problem. That adds a mechanical issue to the inflammatory biological issues- the perfect storm for OA and a good reason to avoid meniscus surgery if you can.

Individual experiments have proven that the concentration of those nasty chemicals in our knee will go down after running, or resistive exercise. Studies have also shown that the health of our cartilage is positively affected by running. Our cartilage seems to like the cyclical loading associated with certain activities. Most studies have shown that the chemical composition of cartilage is not adversely affected by exercise while many studies show that knee pain from arthritis improves with exercise, the exact reason why is yet unclear.

“There is no association or causality between running low and moderate distances and knee OA. There is no causality between running and meniscal injury.” 

 

Can I exercise with arthritis of the knee? 

arthritis in runnersFor more than two decades, the research has clearly shown that exercise is of benefit in people with osteoarthritis of the knee. Exercise improves pain, strength, and decreases muscle atrophy.  Exercise can improve your quality of life and help delay the need for surgery.  So.. if someone tells you to rest because you have osteoarthritis… kindly say no.

Osteoarthritis is not caused by walking too much or low impact activities. If your arthritis pain is due to severe osteoarthritis, then you may need to consider other treatments above and beyond exercise. Exercise has significant anti-inflammatory effects. This is somewhat counter-intuitive, and I often have difficulty convincing people of this.  That’s because far too many people still think the knee arthritis has a wear and tear etiology.  The benefits of exercise are enormous.  There are more than a dozen chronic disease states that will improve if your exercise. Most of you will feel better if you exercise.  The reasons for this are complex, but the results are straightforward. You will be healthier, lighter, feel better, and often have less pain if you exercise regularly—even with mild to moderate osteoarthritis of the knee. 

A proper exercise program to combat the age-related changes that we all experience will include aerobic exercise (walking, running, biking, swimming, etc.), resistance exercise, and balance exercises.  These different forms of exercise help minimize the risk of developing age-related muscle loss (sarcopenia), heart disease, dementia, type 2 diabetes, hypertension, and so on.  This post on our site goes into more detail about the specific exercise programs we should be interested in to optimize our lives for a longer healthspan.  

These two posts on my site go into detail about:

1. How muscle mass and muscle strength affects longevity and

2. 6 reasons why you should perform mostly leg exercises.  

How does exercise improve knee pain due to arthritis? 

The answer to this is much more complicated than you may think.  We feel pain in our joints for many reasons.  Osteoarthritis of the knee is an inflammatory process. We have proteins and chemicals in our knee joint that our body produces.  There are many of these such chemicals.  In sedentary individuals who have the fluid in their knee tested and compared to those of us who are active, we start to see significant differences in the make-up of the chemical milieu that is in our knee joint.  For example… IL-10 is an anti-inflammatory that our own body manufactures inside our knee joint.  After exercise, either resistance exercise or aerobic exercise, the concentration of IL-10 increases. 

The concentration of IL-6, a pro-inflammatory mediator, increases with sedentary behavior.  For those of you who have arthritis, you knew this already. You know how the first few steps you take in the mornings are tough, you’re stiff, and your knee joint hurts.  Well, you have been sedentary, so pro-inflammatory mediators have built up. Now you start walking, and your joints begin to loosen up and feel better.  That’s because your anti-inflammatory mediators are beginning to be manufactured.  

Running and arthritis of the knee

Far too many people still believe that running causes arthritis and knee joint deterioration. Recreational running, even those of us who have been running 20 miles a week for 40 years has not been associated with an increased risk of developing osteoarthritis.  Study after study reveals there is no conclusive evidence that running causes osteoarthritis of the knee; in fact, running may actually slow the functional aspects of musculoskeletal aging.  Various initiatives have evaluated the risk of developing arthritis or the risk of worsening osteoarthritis of the knee in runners. There is no conclusive evidence to suggest that running is going to cause arthritis to worsen.    We published a few posts on this website on the topic of running with osteoarthritis and meniscus tears. Feel free to dive deeper by reading those posts.  

Why you should exercise with knee arthritis

For most people, aerobic activity is associated with improved arthritic symptoms. less pain and less disability.  More importantly, running has not been shown to cause more advanced osteoarthritis. Even as far back as 1986 early studies on runners showed that their bone density increased (that’s good) and there were no signs of increasing osteoarthritis in male or female runners.  Like other aerobic forms of exercise. There are numerous health advantages to running.  For now, it appears very clear that the risk of not performing aerobic exercise is much higher than the risk of causing worsening arthritic pain.  

Osteoarthritis of the knee is associated with an increased risk of all-cause mortality. That means that exercise and maintaining physical activity is critically important for your health and well-being.  Formal programs are starting to emerge across the globe to help people improve their quality of life with arthritis that is not yet severe enough to require joint replacement surgery.  GLA (D) is a program developed in Denmark that has demonstrated significant success in mitigating a lot of the disabling aspects of living with osteoarthritis of the knee. Exercise and walking are essential to decrease the risk of dementia, to lower the risk of heart disease, to maintain or decrease our weight, to clear the cobwebs from our heads, to reduce blood pressure and improve your overall health. Exercise is the best medicine for a joint that has started to degenerate or become arthritic. You are NOT wearing out your cartilage by walking or running. 
Keep on truckin’
 

Disclaimer:  this information is for your education and should not be considered medical advice regarding diagnosis or treatment recommendations. Some links on this page may be affiliate links. Read the full disclaimer.

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About the author:

Howard J. Luks, MD

Howard J. Luks, MD

A Board Certified Orthopedic Surgeon in Hawthorne, NY. Dr. Howard Luks specializes in the treatment of the shoulder, knee, elbow, and ankle. He has a very "social" patient centric approach and believes that the more you understand about your issue, the more informed your decisions will be. Ultimately your treatments and his recommendations will be based on proper communications, proper understanding, and shared decision-making principles – all geared to improve your quality of life.

3 comments on “Exercise and Knee Arthritis Pain: The science of why it works.

  • So, reading between the lines, we should encourage our patients to engage in exercise, despite the pain that accompanies the effort/load of the exercise, correct?

    Am I on track to tell patient’s that if the “same” effort/load is accompanied by increasing intensity of pain, as a trend over time (days), they should reduce the effort/load? And, if “same” effort/load is accompanied by decreasing pain intensity, they should increase the effort/load?

    Thanks for your guidance.

    Joel Dykstra PT, Cert MDT
    Evanston Illinois

    • HI Joel..
      I do think that pain can be a useful guide– with some caveats. During the first 2-3 week acclimatization phase I tell folks that they may experience a short-lived increase in symptoms. Their joints are getting used to the load, etc. Following that, I think the most important message, and one that resonates with the majority of OA patients in the office is that there is no evidence that the discomfort correlates with an increase in OA changes or OA progression. Most are comforted by that last statement and most are happy that they can continue to walk, bike, exercise, etc without fear of harming themselves. It almost seems as if their discomfort is better tolerated when coupled with the knowledge that it does not appear that they are harming themselves. The benefits of exercise – aerobic, resistance, and balance- clearly outweigh any risk there might be in continuing to exercise.

  • Very good info indeed.!It is very very useful atmany points it vanishes the age-old beliefs about knee pain.

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