February 2011

Analyze this: Kids’ shoes

In the moment: Footwear

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Findings suggest divergent gait effects

By Jordana Bieze Foster

The findings of a recent meta-analysis seem likely to fuel the ongoing discussion about the relative biomechanical advantages of footwear relative to barefoot walking or running, but not necessarily in the ways one might expect.

In the January issue of the Journal of Foot & Ankle Research, an Australian meta-analysis of 11 studies found that walking and running in footwear significantly alters spatio-temporal, kinematic and kinetic gait variables in children compared to barefoot gait.

The meta-analysis, which included more than 1200 study subjects ranging in age from 1.6 to 15 years, echoes some of the conclusions reached by researchers from the Hospital for Special Surgery in their study of footwear’s effect on the gait of very young children (see “Thinking Small: Making strides in children’s footwear.”) But there are also points of contrast between the two sets of findings, complicating the question of whether the clinical effects of conventional children’s footwear are positive or negative.

Researchers from the University of Sydney analyzed 11 studies that compared gait in healthy children under barefoot and shod conditions. Study subjects wore walking shoes in five studies, athletic shoes in four studies, and Oxford style shoes in two studies; four studies included multiple types of footwear. Four studies did not describe the type of shoes that were worn.

Both the HSS study and the meta-analysis offer reason to believe that shoes decrease proprioception. In the meta-analysis, this was supported by increases in double-limb support time and base of support during shod walking compared to barefoot walking; the authors theorized that these gait modifications may occur in an effort to improve stability with the loss of proprioceptive input. In the HSS study, increased levels of peak plantar pressure were seen during barefoot gait and in the most flexible (i.e., most barefoot-like) shoe, which the authors suggest is indicative of increased proprioception.

The two sets of findings also both suggest that footwear affects step length and gait speed, but reached opposite conclusions regarding the specific effects. Both found that shoes resulted in an increased step length, but the HSS study found that children walked faster while barefoot, and the meta-analysis found that children walked faster in shoes.

Overall, the meta-analysis found that shoes restricted foot motion during gait. One of the studies analyzed, a German study published in the January 2008 issue of Gait & Posture, found that increasing shoe flexibility led to increases in foot range of motion that more closely approximated a barefoot condition; similarly, the HSS study found that increasing shoe flexibility led to plantar pressure patterns that were more similar to barefoot walking. However, the Australian researchers noted that the Germans still found considerable differences between barefoot and shod walking even in the more flexible shoes.

Looking at running gait, the meta-analysis found that the majority of children ran with a rearfoot strike pattern, 62% while barefoot and 97% while shod. This is consistent with previous studies of adult runners and is also consistent with Nike Sport Research Laboratory findings that more than 80% of children over the age of three and 93% of those over age six ran with a rearfoot strike pattern while barefoot (see “Kids’ loads shift underfoot.”)

Overall, the meta-analysis found that shoes had no significant effect on ground reaction forces during running, which is consistent with studies of adults. However, shoes did have a positive effect on tibial acceleration; there was a trend for decreased rate of loading at impact in shoes compared to barefoot, which is consistent with Harvard research in adults (see “Impacts spell injury.”)

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