The lower back bears a double burden: supporting the weight of the upper body and being highly mobile – rotating, flexing and extending. The lumbar spine and the lower back muscles work hard to perform these varied tasks, but they don’t work alone. Proper lower back muscle engagement and spinal alignment depend largely on other joints and muscles in the body, particularly from the lower body. Often enough, lower back pain has its source beyond the back itself.
Back Pain and Supination
Your feet – your main point of contact with the ground – are a good place to start looking for causes of back pain. The way your foot strikes the ground determines the angle of every joint up to the lower back, including the ankles, knees and hips. The angle of your joints in turn determines the length and tension of the muscles from your feet to your back. If muscles are tight or overstretched, they can’t do their jobs right.
Over-pronation, or the condition in which the ankle rolls inward when your foot strikes the ground, is the more common and more discussed type of gait dysfunction that can cause back pain. But, for some, the problem is the opposite: over-supination. This occurs when your weight is primarily distributed along the outside edge of your foot, meaning your ankle rolls to the outside. If you’re unsure as to whether you over-supinate, look at the bottom of a pair of shoes you’ve worn for some time; if there is more wear on the outside edge, you’re an over-supinator.
Over-supination can cause back pain and other problems in a number of ways. First, since normal muscle recruitment is inhibited, your lower back muscles end up being employed to help swing the leg forward from the hip on each step. Also, the ankle, knee and hip joints are susceptible to injury as they are misaligned when the foot rolls outward. Add to misalignment the fact that the joints are exposed to excess shock; the arch of the foot normally absorbs shock when the foot strikes the ground properly. If you over-supinate, your weight isn’t distributed over the arch and the rest of your body is left to absorb the shock. Ankle sprains, plantar fasciitis, joint wear, chronic back pain and bone fractures are all risks for the over-supinator.
Generally, over-supination is caused by physical abnormalities like bow-leggedness or very high arches. It can be exacerbated by tight calf muscles that encourage the ankle to roll to the outside. You should have your gait analyzed by a physical therapist or sports therapist to determine 1) what muscles need to be stretched or strengthened to encourage a more efficient foot strike and 2) what type of shoe would be best. There are special shoes available to over-supinators whose padding encourages the foot to land more toward the center; these are particularly helpful to athletes. Custom or standard supinator insoles may be more appropriate for your situation.
Taking steps to correct your gait will give you whole-body payoffs. When seeking out back pain causes, don’t forget to look toward other parts of the body.