The Effects of Endurance Sports on Your Joints

By W. Stan Ragon, M.D.

I always hated running growing up, but in the Navy I was required to run one and a half miles twice a year as part of the physical fitness test. I started running right before going on active duty, at the age of 32, just so I could pass the test. I came to enjoy it, and I gradually increased the distances I was running. Within three years I had finished several half-marathons, a marathon, and a half ironman triathlon.

For years, I used the excuse that “running is bad for your knees.” But after researching the evidence, I discovered that my excuse simply wasn’t true.

In 1991, a group of researchers studied and followed thousands of runners who voluntarily participated in a study that would seek to understand the effects of running on the body. The study followed 75,000 runners over a seven-year period. Runners had roughly half the risk of hip replacement as walkers. It was also discovered that the rate of arthritis in the runners was less than or the same as the non-runners. (This statistic did not apply to those who had had a previous injury.)

Part of the reason why runners have less arthritis than non-runners is that they typically weigh less than non-runners. If you carry fewer pounds of extra weight around everyday, then it is going to take a lot of stress off of your joints while doing everyday activities.

Another benefit of running for your joints is that impact exercises increase bone density and help nourish the cartilage. This means that your joints may be less likely to wear down, and fractures may be less likely.

The prevailing thought is that running increases the impact on your joints and this could be a direct contributor to developing arthritis. However this has also been proven to be false.  In a separate study, runners and walkers were both outfitted with motion and pressure sensors to measure how long the participant’s foot was in contact with the ground and the forces generated when the foot was on the ground. It was learned that because runners take longer strides than walkers, the amount of time the foot is in contact with the ground and the impact on the joints over a given distance is about the same since walkers take more steps to cover the same distance.

Why did many others and I believe so many inaccurate theories about running? It could be because we simply don’t want to get off of the couch, but it could also be because of the things that we hear in the news.

At times, the media has sensationalized the fact that endurance athletes experience heart attacks. However, the percentage of endurance athletes that die suddenly from a heart attack is much lower than in the general population. It only makes headlines because it’s so rare.  If an obese smoker died while sitting on their couch, it would hardly be newsworthy.

As an orthopedic surgeon, I have seen that the better shape that someone is in before surgery, the easier their recovery will likely be. One problem that I occasionally have is holding athletes back after surgery. They sometimes want to jump back into their exercise routine before it is appropriate. The body still takes time to heal, regardless of how good the injured area feels after surgery.

If you are starting a running program, be sure to wear proper running shoes and don’t do too much, too soon, too fast (the most common cause of overuse injuries in runners). Your heart and lungs adapt faster than your connective tissues, which take time to adapt to the impact of running. They need time to recover and repair between sessions. A general rule of thumb is to increase your running mileage by no more than 10% per week.

Before starting any type of new exercise routine you should talk to your medical doctor so that he or she can evaluate other potential problems such as diabetes, high blood pressure, or heart disease. Of course, it is well established that exercise helps with those medical problems, too! So I encourage everyone to exercise to the extent that they are able. If one can’t run, then try biking, swimming, or weight training. Exercise is truly the best medicine, and it’s not bad for your joints, despite the common beliefs that it is.