Effect of Shoe Flexibility on Plantar Loading in Children Learning to Walk

Abstract

Background: In a previous pilot study of “cruisers” (nonindependent ambulation), “early walkers” (independent ambulation for 0–5 months), and “experienced walkers” (independent ambulation for 6–12 months), developmental age significantly affected the children’s stability when walking and performing functional activities. We sought to examine how shoe structural characteristics affect plantar pressure distribution in early walkers. Methods: Torsional flexibility was evaluated in four shoe designs (UltraFlex, MedFlex, LowFlex, and Stiff based on decreasing relative flexibility) with a structural testing machine. Plantar pressures were recorded in 25 early walkers while barefoot and shod at self-selected walking speeds. Peak pressure was calculated over ten masked regions for the barefoot and shod conditions. Results: Torsional flexibility, the angular rotation divided by the applied moment about the long axis of the shoe, was different across the four shoe designs. As expected, UltraFlex was the most flexible and Stiff was the least flexible. As applied moment increased, torsional flexibility decreased in all footwear. When evaluating early walkers during gait, peak pressure was significantly different across shoe conditions for all of the masked regions. The stiffest shoe had the lowest peak pressures and the most flexible shoe had the highest. Conclusions: It is likely that increased shoe flexibility promoted greater plantar loading. Plantar pressures while wearing the most flexible shoe are similar to those while barefoot. This mechanical feedback may enhance proprioception, which is a desirable attribute for children learning to walk. (J Am Podiatr Med Assoc 103(4): 297–305, 2013)