Studies assess school shoes, flip-flops
By Jordana Bieze Foster
Researchers from the University of Sydney in Australia have identified gait changes associated with pediatric footwear that may help explain foot complaints that have been reported in children.
In one study presented at the i-FAB congress, Oxford-style school shoes were associated with changes in variables related to pronation, but those changes varied throughout the gait cycle. In a second study, flip-flops were associated with significant gait alterations in the sagittal plane.
Both presenters cited a 2010 survey-based study, also conducted at the University of Sydney, in which parents of children between the ages of four and 12 reported that 28% of those children had experienced a foot problem in recent weeks and that 26% of those problems resulted in cessation of activity. Nearly half the parents surveyed said they thought their children’s foot problems were related to footwear.
In the school shoes study, investigators analyzed 20 children (11 girls) who walked and ran on a 12-m walkway at self-selected speeds while barefoot and while wearing leather lace-up Oxford style shoes with polyurethane midsoles and outsoles.
During loading, the shoe condition was associated with significantly greater ankle range of motion (ROM) than the barefoot condition in both the sagittal and transverse planes. However, during midstance, the only significant difference was that the shod condition was associated with less ankle ROM in the frontal plane. And, during propulsion, the researchers found significantly greater ankle ROM in the sagittal plane but significantly less ankle ROM in the frontal plane compared to the barefoot condition.
The findings suggest the shoes are facilitating pronation during loading but limiting pronation during midstance and also limiting resupination during propulsion, said Caleb Wegener, BAppSc(Pod) Hons, a doctoral student in exercise and sports science at the university, who presented the results at the i-FAB congress.
“School shoes have a mixed effect on rearfoot pronation, and this may be beneficial or it may be detrimental,” Wegener said. “The changes are small, but as a percentage they are fairly significant.”
In the study on flip-flops (or thongs, as they are known in Australia), researchers analyzed 13 children (eight girls) as they walked and jogged on a 12-m walkway while barefoot and while wearing flip-flops.
The investigators found the footwear was associated with significantly less hallux dorsiflexion than the barefoot condition at three timepoints during walking: prior to heel strike, at toe off, and during swing phase. These findings were consistent with those of a previous study by the same group, which was presented last year at the International Society of Biomechanics meeting in Brussels, Belgium.
The current study also found that wearing flip-flops was associated with significantly more midfoot plantar flexion than the barefoot condition throughout stance, during both walking and jogging. Ankle angle also indicated more plantar flexion at heel strike for the flip-flop condition during both walking and jogging.
The observed gait changes, however, were small, according to Angus Chard, a podiatrist and doctoral student in exercise and sports science, who presented the findings at the i-FAB congress.
“If we had fatigued the children before testing, we might have seen more pathological effects,” Chard said.
Wegener C, O’Meara D, Hunt AE, et al. Three dimensional ankle kinematics in children’s school shoes during running. Presented at 3rd International Foot and Ankle Biomechanics Congress, Sydney, April 2012.
Chard A, Greene A, Hunt A, et al. Effect of thong-style flip-flops on children’s midfoot motion during gait. Presented at 3rd International Foot and Ankle Biomechanics Congress, Sydney, April 2012.
Penkala S, Harris L, Hunt A, Naughton G. Foot complaints of children aged four to twelve years, sex differences and activity—a cross-sectional survey of parents. J Sci Med Sport 2010;12(2):Abstract 218;e107.
Chard A, Smith R, et al. Effect of thong-style flip-flop footwear on children’s hallux sagittal plane motion during gait. Presented at the International Society of Biomechanics meeting, Brussels, July 2011.