Does Running Cause Knee Arthritis?
Many assume that the repetitive impact on joints during running will cause or contribute to the development of arthritis in their leg joints. However, there is no evidence that running will increase the risk of arthritis on healthy joints despite extensive and long-term research. Many studies even suggest runners could have a slight advantage in avoiding arthritic leg joints. The best way to prevent arthritis is to be active but in the most ergonomic way possible. Higher physical activity (including things like running) reduce the risk of requiring knee joint replacement surgery because of arthritis.
What Causes Knee Arthritis?
There are several factors that can cause arthritis. Congenital joint deformities or instability, joint injuries, and auto-immune disorders can all lead to developing arthritis in any joint and at any age. For individuals with healthy joints the most significant contributor to arthritis is obesity. Women are also at slightly higher risk for arthritis than men.
Running doesn’t cause arthritis, but it can make it worse if you already have other joint problems. If a joint injury or joint pain results in an irregular running pattern (limping or asymmetrical step length) or in a joint that doesn’t move the way it is supposed to, it is likely to increase cartilage loss, swelling, and pain. But this is true of any activity involving injured joints, even walking or prolonged sitting and standing. This is not to say that people with joint injuries shouldn’t move their joints or be active, that should be discussed with a doctor. For the most part, however, movement and strengthening are beneficial for injured joints and even for reducing pain from arthritis. The key is picking a physical activity and intensity so that one can focus on training or retraining normal movement patterns during and after it heals.
Why Doesn’t Running Cause Arthritis in Leg Joints?
The simple answer is because running reduces the risk of obesity and obesity is the leading preventable cause of arthritis. However, research indicates the answer to this question may be more subtle. It’s a question of force exerted over distance traveled. Runners are placing as much as 8x the force each time their foot hits the ground than when walking, but their foot hits less often and stays there less time. A runner will have a lower or similar total impact force to leg joints as a person walking the same distance.
Additionally, the impact to joints is reduced when they are flexed during impact. Then joints give slightly during impact, acting like a spring to disperse the force. For example, runners who use good form will have a slightly bent knee, ankle, and hip when their foot hits. This allows the force of the impact to be distributed more evenly across a larger surface area of more joints. With brisk walking (or running using poor form), the knee is in full extension or even “locked out” during impact and the heel strikes first. This focuses the force of the impact on a small area of the heel, ankle, knee, and straight up into the hip joint.
A Good video discussing the importance and bio-mechanics of running and the knee joint. This is a common discussion theme among ‘barefoot’ or ‘minimalists’ running trend but isn’t exclusive to that particular method of running. Good knee mechanics during any activity is the key to not getting injured.
Can I Reduce the Risk of Arthritis After an Injury to a Joint?
The first thing to understand about joint injuries and arthritis is that you may not be able to stop some injuries from developing arthritis over time. Some injuries will permanently alter the joint mechanics so much that wear is inevitable. You can always, however, slow the progression and reduce the pain by exercising the joints and strengthening the supporting muscles.
The second thing to understand is that none of the following advice is intended to replace or override a doctors recommendations. Certain injuries have to be immobilized or limited during healing. If you have an injury, start by being evaluated by a doctor. Follow the doctor’s or physical therapist’s recommendations, but you can keep this information in mind during your recovery.
Focus on How the Joint Moves
Neurologically speaking, humans adapt to change quickly, but are also resistant to change. For efficiency, neurons tend to repeat what it has practiced unless forced to change patterns (consciously or unconsciously). When an injury occurs to a joint, the nervous system responds to the pain, swelling, etc. by tightening muscles around the area in an effort to prevent further injury. Unfortunately, this highly beneficial initial response can become the cause of chronic pain long after an original injury has healed. If the correct joint/muscle movement patterns are never retrained it can cause chronic pain, muscle tightness, and eventually the joint will degrade.
Spend time every day moving the joint through the entire range of motion slowly and methodically without any extra weight or resistance. Use the other joint as a reference for how the joint should move (assuming it is a healthy joint). For the knee joint, this means bending the knee as much as possible and then straightening as much as possible (but not into ‘hyper-extension’). If the motion is restricted, spend extra time actively stretching each time you come back to the resistance. Repeat this for several minutes every day until the injury has completely resolved (no pain, swelling, or unusual movement). This will help retrain normal muscle and joint movement and increase your natural awareness of a joints positioning (proprioception) after the injury
Consider How The Injury Affected Other Joints/Muscles
Our joints and muscles almost never work solo. They work in coordination with each other to produce a fluid, functional movement. An injury to the knee, for example, can disrupt normal muscle and joint movement in a multitude of other joints including: toes/feet, ankles, hips, pelvis, the low back, and any joints on the other leg. As discussed above, neurons do what they practice. So include all the areas that have pain, muscle tightness, or swelling in your recovery exercise, as well as the joints directly above or below that.
For example, your right knee was injured, but during your down time and recovery, your low back and left ankle became sore. Your recovery routine should include the left ankle and knee, the low back and mid back region, your right hip/pelvis region, in addition to your right knee.
Balance and coordination exercises are also of particular importance during recovery because it specifically challenges muscle groups to coordinate with each other. Standing on one leg, stepping over things, side stepping, walking heel-to-toe on a line, or standing on a foam pad are all good activities for improving muscle coordination.
Increase the Intensity of Activity Slowly
Depending on the type of injury, you may not be able to return to the same activities after recovering as you did before you were hurt. However, goals are important and being active in some fashion is the best way to prevent arthritis. Start slowly and listen to how your body responds. There is no shortcut for this and being overly aggressive can prolong your recovery. Most athletes know the motto “No Pain, No Gain” and there is some truth to this statement. How muscles are strengthened, stretched, and trained has a lot to do with making your body do more than it usually does. Soreness and swelling are also expected when recovering from an injury (see the next bit of advice), but it shouldn’t be so significant that progress is being consistently lost. If increased activity causes increased pain, try something less intense for a while, but don’t eliminate activity. Joints and muscles are literally designed to facilitate movement. They can’t fully heal without it.
Treat Pain and Soreness
Most pain from an injury or surgery is rooted in inflammation. Mild swelling is even common after weight lifting and rigorous exercise. Despite being normal, it shouldn’t be ignored. Pain causes bad movement patterns, and bad movement patterns cause inflammation and pain. It’s the cycle of inflammation, pain, and injury that can lead to chronic problems.
Use over-the-counter anti-inflammatory medicines and ice consistently to treat inflammation during your entire recovery. Heat can also be useful later in recovery for reducing muscle tightness, but should be followed by 20 minutes of ice to mitigate swelling.
Don’t ignore pain and soreness that is becoming chronic. See your doctor again, get a second opinion, or ask to see a physical therapist if you aren’t getting back to normal after an injury or surgery.