A couple of weeks ago in class we debated whether running causes knee problems. Everyone seems to believe if you run for too many years, you will eventually have bad knees, arthritis or both.

Approximately one third of serious runners will incur an injury in a given year, and approximately one third of the injuries will involve the knee. Biomechanical studies on running reveal the tremendous cyclic forces to which the knee is subjected and show that forces of up to 300% body weight can occur even during normal walking, and this may rise to 550% during running.

I read a fascinating study that measured the changes in the cartilage volumes in the tibia, patella and medial and lateral meniscus (the cartilaginous tissues that provide structural integrity to the knee) after the extreme dynamic loading that occurs in long-distance runners. It also examined the rate of recovery from the alterations occurring at the knee joint due to loading during distance running.

In short, although there were significant changes after a 5, 10 and 20 km run, the conclusion on the basis of the study was that the cartilage is able to adapt well to the loads caused by running and that the articular structures were found to recover rapidly so that exercise could be continued after a short rest without reservation.

Our bodies seem to have been designed to withstand the pressure of running. The affected tissue is not only adaptable but regenerative, rebuilding itself within a short period of time. This study revealed that after 1 hour of rest no significant reduction of cartilage volume was measured for the patella, the tibia or the lateral and medial meniscus.

The best evidence that running does not lead to pain and eventual arthritis comes from an ongoing study of the Fifty Plus Runners Association. The study was launched in 1984 when all the runners were at least 50, and updated every five years or so since. Many of the runners are now in their 60s, 70s, or older.

The newest update to this study was published last September in Arthritis Research & Therapy. It compared the runners, who averaged about 26 miles a week, to a matched set of controls, who averaged about two miles a week.

The study’s major conclusion: The runners experienced “about 25 percent less musculoskeletal pain” than the control group. That’s a major check mark in my book for staying active.

The most enjoyable reading I found on the topic came from Paul Ingraham, a science writer and runner who suffered from a severe case of ITBS and subsequently studied knee injuries for several years.

He writes, “Both kinds of runner’s knee are repetitive strain injuries. Humans are indeed born to run in many ways, but we’re certainly not indestructible…”

He identifies two common “runner’s knee” conditions: pain on the side (iliotibial band syndrome, or ITBS), pain on the front (patellofemoral pain syndrome, or PFPS) and provides a checklist of symptoms to help you identify the cause of your pain. It’s fun and informative reading.

Every source seems to agree on several things we can do to help prevent long term damage to our knees due to injury and/or prevent the onset of osteoarthritis regardless of our chosen sport (ITBS in particular also affects cyclists and hikers).

Avoid Carrying Extra Weight: Increased body weight, which adds stress to lower body joints, is a well established factor in the development of osteoarthritis. Your knees, which carry the brunt of your weight, are particularly at risk. For every pound you gain, you add 4 pounds of pressure on your knees and six times the pressure on your hips.

Recent research suggests that excess body fat produces chemicals that travel throughout the body and cause joint damage, which would mean obesity plays a systemic, not just a mechanical, role in osteoarthritis onset.

Avoid Overuse/Injury: While running itself doesn’t increase the risk of osteoarthritis, running injuries can–especially when you delay treatment or rush recovery. If an injury is not properly cared for, the non-healing of it can cause the degenerative process of arthritis to start in the joints.

Train smart: don’t ramp up too quickly, don’t train if you’re Injured.

Be Strong: Studies show that weakness of the muscles surrounding the knee is associated with osteoarthritis, especially in women, and makes the pain and stiffness worse after onset. Strengthening exercises for thigh muscles are important in reducing the risk.