The Impact of Flat Feet
By Mark Charrette, DC
In previous columns, I've reviewed the effects of abnormal Q angle and leg-length inequality on the pelvis and spine, as well as on the knee joints. I've discussed the various symptoms and clinical problems reported by patients with excessive pronation or sports-related injuries. This time, I want to call to your attention to (or remind you of) an interesting study that demonstrated how the lack of an arch can have a significant physiological impact.
It makes sense to chiropractors that abnormal foot biomechanics would result in more difficult physical functioning. Intellectually, we can hypothesize that not having an arch would make push-off less effective, since the foot does not become the needed "rigid lever" at toe-off. This, therefore, would make walking more inefficient and more energy-consuming. The end result would seem to be more energy usage and greater fatigue than necessary from walking. On a gut level, this concept feels right – but is it scientifically accurate?
A 1988 study1 investigated this subject, and came up with some very interesting conclusions. The results of this study are very important to chiropractors, whether they treat a general practice or work with performance-based athletes. Judge for yourself whether some of your patients who had not been considered for foot orthotics might benefit greatly.
Energy Use and Flat Feet
The three researchers who wanted to investigate the above hypothesis came from backgrounds in physical medicine, physical therapy, and rehabilitation. Their stated goal was to perform a "comparative study ... to assess the effects of arch support on oxygen consumption."1 The experimental subjects were 40 women between the ages of 18 and 38 years. All women were in general good health, with no foot or lower extremity complaints. From weight-bearing X-ray measurements, 20 women were selected who met the diagnostic criteria of flat feet. The other 20 healthy women were used as a matched control group.
All subjects had several physiological parameters tested – at rest, while walking on a treadmill at three levels of speed and incline, and after recovery. The measurements included ECGs, systolic and diastolic blood pressures, pulse rates, and oxygen consumption. Energy cost of walking was calculated by multiplying the milliliters of oxygen consumed each minute by the weight of the subject in kilograms. This initial test provided the baseline for all women in the study.
The 20 women with flat feet were provided with custom-made arch supports, which they wore full time for two weeks. At that point, the same physiological testing procedures were again performed on all subjects, with the experimental group wearing their custom arch supports.
The control group showed no differences in any of the measurements from the first test to the second test. There was no change in the resting measurements of the group wearing medial arch supports. This demonstrates the consistency and validity of the measurements performed by the researchers.
Significant differences were seen in the walking and recovery measurements of the experimental group (those wearing the arch supports). Their heart rates were significantly slower, their systolic blood pressures were lower, their consumption of oxygen was less, and their calculated energy cost was much less. These differences were most obvious at the faster walking speeds and the higher inclines, as could be anticipated.
Suitable Arch Support
A control group was used, since it was possible that re-testing two weeks later might demonstrate improved performance because the subjects were more experienced with the test procedures. In this study, the control group did not show any significant change between the two tests. The significant improvements in physiological performance in the experimental group can be confidently ascribed to the use of the arch supports. The study's authors stated that "oxygen consumption can be decreased in patients with flat feet simply by applying a suitable arch support."
What is a "suitable arch support?" These researchers took weight-bearing imprints of each experimental subject's feet, made several measurements, and built a support of the medial arch from polyethylene. They then inserted this custom-made arch support into the leather of the shoe to prevent displacement. So, in this study, these orthotics were built based on a "weight-bearing, functional position" image of the foot.
The large and significant differences between the two tests in the group wearing arch supports should make us all think twice when considering the benefits of orthotics in our patients. Whether a patient is a "weekend warrior" or an internationally competitive athlete, an increase in performance can generally be predicted when the flat foot is supported by a suitable orthotic.2-5
When a patient complains of difficulty in walking, inability to stick to a jogging exercise program, or even has generalized fatigue, it is our duty to examine their feet for the presence of low or collapsed arches. A well-made custom orthotic may be the simple and cost-effective solution to a physiological problem.
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