With enough wear and tear, all mechanical devices (e.g., engines, hinges, tires, etc.) degrade.
For many years, conventional wisdom said the same about our knees. They were just biological hinges that would inevitably give out over time, especially with overuse, such as running. Trying to figure out how to keep your knees healthy was a lost cause, especially for athletes.
A study that began in 1984 turned this notion on its head.
How to Keep Your Knees Healthy: The Shocking Truth
Doctors at Stanford tracked two study groups to test the hypothesis that knees are analogous to mechanical hinges that wear out over time.
The study followed 45 recreational, long-distance runners and 53 non-runner controls over 18 years. The participants were predominantly men with a mean age of 58. The runners had at least 10 years of running experience and ran an average of five hours per week.
At the beginning of the study, 6.7% of the runners and 0% of the non-runners showed X-ray evidence of arthritis. The participants had X-rays of their knees taken every few years.
At the end of the 18-year study, the results flabbergasted everyone: 20% of the runners had evidence of some form of arthritis, while 32% of the controls did. Even more startling? Only 2.2% of the runners had severe, disabling arthritis, while 9.4% of the controls did.
The non-running controls had over four times the rate of severe arthritis in their knees as the runners. The results contradicted the original hypothesis and debunked the myth that running damages knees.
Important Caveats
The study’s participants were:
- Uninjured
- Mostly men
- Over age 50
- Recreational, long-distance runners
The study definitively answered whether knees wear out over time for that population. They don’t.
Unpacking the Conventional Wisdom
Where did the notion that athletes have “bad” knees (or are destined to) come from?
Countervailing literature on high-intensity sports, including ballet, soccer, wrestling, and weightlifting, shows that athletes can have three to six times the level of degenerative arthritis as non-athletes.
When you examine the literature for sports that have increased rates of degenerative arthritis and remove injured athletes, there’s no increased risk of degenerative arthritis. The literature tells us that running makes a healthy, uninjured knee healthier.
Conversely, a sport that injures a knee causes the knee to wear out faster. The goal is to safely participate in sports that can strengthen the knee without injuring it. How can you find the right balance?
Let’s examine the knee’s anatomy to understand why this happens and how to keep your knees healthy with appropriate exercise.
The Knee’s Anatomy
The knee contains “hard stuff” and “less hard stuff.”
The “hard stuff” is bones:
- Femur
- Patella
- Tibia
- Fibula
The “less hard stuff” is cartilaginous tissue, tendons, and ligaments:
- Lateral meniscus
- Medial meniscus
- Lateral collateral ligament
- Medial collateral ligament
- Anterior cruciate ligament
The lateral and medial meniscus act like washers to cushion the areas between the bones. The ligaments connect the bones and align your knee.
When the anatomy works well, exercise perfuses the soft tissues and cartilage. Cartilage is avascular, meaning it contains few or no blood vessels. The medial meniscus, for example, gets nutrition from the synovial fluid.
Synovial fluid bathes and lubricates the entire knee joint when you move your knee. The more effectively you move your knee, the more you nourish those soft tissues.
If you injure your knee — for instance, if you tear a meniscus or ligament — you change the knee’s mechanical alignment. At that point, you’ve disturbed the anatomy of the knee and changed how the force is distributed within the joint, which increases your likelihood of generative arthritis and joint wear.
In contrast, maintaining an injury-free knee strengthens it.
How to Keep Your Knees Healthy
With this understanding of anatomy and pathophysiology, here’s how to keep your knees healthy:
- Exercise. It strengthens the bones and enhances the knee’s surrounding musculature, protecting and aligning it. Exercise also moves the synovial fluid around, maintaining cartilage health.
- Practice extreme caution with high-impact, injury-prone sports. Every sport, even running, can injure you. If you participate in high-risk sports, maintain your flexibility and strength, and don’t overdo it.
- Remember that running is a double-edged sword. When done properly, it’s good for your knees, but if you injure your knees while running, your risk of arthritis increases. Practice safe running techniques:
- Pay attention to your gait. Watch videos online or talk to a coach.
- Wear appropriate footwear. Use insoles if you need them for proper alignment.
- Avoid carrying extra body weight if possible, but if you must, maintain strength and flexibility. Extra weight demands more of your knees.
If you feel pain, remember that musculoskeletal pain is a message from your body. Don’t ignore it. Figure out what your body is trying to tell you.
Knee pain can be a valuable lesson if you listen to your body and decipher its message. Did you run too far? Do you have a bad gait? Do you need different shoes? Listening to your body is the best way to keep your knees healthy.
At Banner Peak Health, we’re proud to offer the resources you need to achieve optimal health through our Outperform program, including access to fitness instructors. Contact us today to take advantage.
