Medical Moment: Running & Knees

13 Aug Medical Moment: Running & Knees

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Dr. Kent Gaylord, Board Certified in Family Practice

Dr. Kent Gaylord answers this week’s question: Does Running Wear Out My Knees?

Does exercise wear out a joint?

The simple answer is: no.

Osteoarthritis (OA) or degenerative joint disease occurs when the smooth shiny cartilage that lines the joint deteriorates.

Is running and jogging harmful for the knees?  Is exercise the culprit of this deterioration?

Research seems to indicate no.

A 2006 study compared rates of OA related disabilities between 539 runners and 423 non-runners over a 21 year period. At the conclusion of the study, researchers found that the non-runners had osteoarthritis-related disabilities twice that of runners.

A 2008 Stanford University study followed 500 longtime distance runners over age 50 for nearly 20 years. At the end of the study, only 20 percent of runners experienced arthritic knees as compared to 32 percent in the control group.

Another study tracked 74,752 runners over 7.1 years and 14,625 walkers over 5.7 years looking at the number of hip replacements and cases of osteoarthritis in each group. The results found runners had fewer cases of osteoarthritis and needed fewer hip replacements than the walkers.

How can we explain these results?

Some people think of joints much like a car tire, where the joint only has only so many miles on it and then wears out. This is not the case. Animal models show that exercise promotes cartilage thickening and protects its stretchy properties. Cartilage is living tissue but it does not have arteries that deliver blood. Instead it relies on movement of the joint to create a pumping action that circulates fluid containing oxygen and nutrients. Joints were meant to be used.

If osteoarthritis is not the caused by exercise wearing out the joint, what is the cause?

The answer is complex, and often no single cause can be identified, here are a few of the most likely culprits.

1)  Family History: Up to 50% of osteoarthritis is thought to be related to an inherited tendency to development joint degeneration.

2) Weight: Excess body fat is one of the main risk factors for OA.  Overweight people are significantly more likely to develop OA than those that are of normal weight.

3) Injury: If you have had a prior injury (ligament, fracture of joint, etc) where the knee is already pushed toward osteoarthritis, running on that knee may accelerate the osteoarthritis.  For instance tears to the anterior cruciate ligament (ACL) carry a 70 percent risk of OA within 10 to 15 years.

4)  Rheumatoid Arthritis or other autoimmune diseases that cause chronic joint inflammation.

Bottom line: Joints are meant to be used. I am a strong believer that it’s much better to be physically active than to hold back to protect your joints.

If you are starting with uninjured joints and don’t have pain or swelling with the activity you are doing such as running, its unlikely you are harming them. But remember to avoid sudden increases in how far or how fast you run. Sudden increases in mileage or effort can cause injury. For those training for a special event such as a marathon (or upcoming Imogene Pass run), don’t increase your effort by more that 5 to 10% per week. If you notice pain or discomfort that doesn’t promptly improve with rest, back off – you may be pushing things too fast.

Editor’s note: The Telluride Medical Center is the only 24-hour emergency facility within 65 miles.As a mountain town in a challenging, remote environment, a thriving medical center is vital to our community’s health.

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