November 2010

Out on a limb: Creatures of comfort

Jordana Bieze Foster, Editor

Benno Nigg, PhD, isn’t exactly on the barefoot running bandwagon. Essentially, the internationally lauded foot biomechanist thinks barefoot running is a fashion trend that tends to recur every 25 years or so  — like babydoll dresses or skinny ties.

“The fashion adaptation to the barefoot idea will stay fashion, and it will disappear in a short time. In 2035 it will be back again,” the director of the Human Performance Lab at the University of Calgary told attendees at the International Foot and Ankle Biomechanics (i-FAB) meeting in September.

Nigg’s research does suggest that the increased muscle activity associated with barefoot and minimally-shod gait is beneficial. But he also believes that muscle activity – and, therefore, foot function – is strongly influenced by comfort.

In a 2001 study of a military population, Nigg and colleagues found that shoe inserts significantly reduced injury incidence during a four-month period compared to footwear alone. Six types of inserts were studied; each subject was issued the type of insert that he or she rated as being most comfortable. Interestingly, subjects’ perceptions of insert comfort varied widely, with each different insert receiving a top ranking from at least five subjects.

Because the inserts differed from each other in terms of biomechanical effects, the authors hypothesized that the reduction in injury rate had less to do with kinematics and kinetics than with the common denominator of comfort. A person whose footwear is optimally comfortable, in theory, is most likely to adopt a pattern of walking or running that is ideal for that person, and therefore less likely to suffer an injury.

This idea, though it evolved from studies of athletic footwear, may have applications in other areas of lower extremity healthcare (diabetic neuropathy being an obvious exception). It’s particularly interesting in light of recent research on footwear and rheumatoid arthritis (see “Choosing shoes for RA.”)

Researchers from New Zealand found that many patients with RA chose footwear that was considered “poor” according to criteria based on support and stability. But they also found that patients claimed to be making their footwear selections based on comfort and fit.

This raises the question: If an RA patient with pain-wracked feet actually finds footwear that is comfortable—even if they’re moccasins or flip flops—is that really a poor choice? That study has yet to be done, but based on Nigg’s findings, I would be willing to bet that shoe comfort is as strong a predictor of function in RA patients as shoe structure.

The challenge this line of thinking presents for practitioners is that comfort is incredibly subjective. The aforementioned 2001 study suggests that arch type and plantar sensitivity to vibration may influence comfort, but we’re a long way from developing any predictive algorithms along those lines. So it’s really up to you to assess your patients’ comfort and determine how that may or may not be affecting their clinical outcomes.

Of course, for some people, optimal comfort may come from wearing no footwear at all. Even when it goes out of fashion.

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