I’m sure most of you have many times had the experience of being asked by a sedentary (i.e., non-runner) individual, “Isn’t running bad for your knees?”, or “All that pounding; aren’t you going to get arthritis?” Somehow, a myth has become accepted as fact by the general populace that while running may be good for your heart and lungs (as well as waistline), it wreaks havoc on the knees, hips and especially, the spine. Walking, the theory goes, is much safer and better for you since the joints are not placed under such great stress. Is this true? Are runners more likely to develop premature arthritis or back pain?
To answer this, we must first understand what is meant by the term “arthritis.” Literally it means “inflammation of the joint,” but in reality this term describes only one aspect of the problem. A more accepted term for the type of problem we are dealing with is “degenerative joint disease,” since this more accurately describes the gradual erosion of the protective cartilaginous covering of the joint surface. As the bone underneath the cartilage is exposed to direct pressure, pain and oftentimes inflammation results. What causes this? No one knows for sure. While some experts argue for a possible genetic link and others support a theory involving the autoimmune system, most feel comfortable with the long-held belief that excessive mechanical forces are to blame and they point to the fact that the disease primarily affects the weight-bearing joints as evidence. If we accept this, it would only seem to be common sense that running, with its 3-4 times increase in body weight at heel strike, would hasten this process.
The problem with this assumption is two-fold. First, while it is true that with running the body must contend with a great increase in ground-reaction/gravitational forces when compared with walking, the fact of the matter is we are for the most part well-adapted to do this. The normal, efficient running gait provides several shock-absorbing mechanisms, such as foot pronation and increased knee flexion during early stance, which effectively protect the joints from these increased forces. The brunt of the force is actually being dealt with by the muscles and ligaments, so in reality it is these structures, not the joints, which are at greatest risk for breakdown. Second, there is substantial evidence that the repetitive motion and intermittent joint pressure changes stimulates circulation and enhances nutrition and lubrication of the joint, in effect aiding in regeneration and restoration of normal cartilage. So in truth, running may actually retard or prevent to some degree the degenerative process we normally associate with aging.
Several studies appear to back this up. One, completed just a few years ago, looked at a large group of males who had run consistently for at least 30 years. When compared with a group of same-age, sedentary men, their knee and hip x-rays showed no evidence of increased incidence of degenerative joint disease. In fact, there was some indication the opposite was true!
Another study concerning degenerative joint changes in the lumbar spine compared x-rays of 450 members of the Bihl tribe in India (a very physically active culture), ages 15-55, with similar age groups in Sweden and the United States. The results showed disk-space narrowing in 80% of the Swedish group (heavy laborers), 35% narrowing in the U.S. group (light workers), and only 9% in the Bihl tribe at age 55. The incidence of disk narrowing was 5% in all three groups at age 15, which indicates that age is not coincident with disk degeneration. While this study did not involve running specifically as the activity of the Indians, and though other factors such as diet and heredity may play a role, the clear difference in these figures certainly supports the argument that physical activity is beneficial to the joints, not harmful. Given the relatively small number of runners I have seen over the years with serious back problems, I would wholeheartedly agree.
So don’t worry about those nay-sayers and their out-dated myths. You know they’re only trying to explain why they aren’t joining us.
