Effect of a Discomfort-Inducing Textured Insole on Balance and Gait

Introduction: Muscle weakness on one side of the body is a common consequence of a stroke, which frequently results in asymmetry of stance and gait. Thus, the improvement of symmetry of balance and gait is a rehabilitation goal for individuals with hemiparesis due to stroke. The overall objective of this research was to investigate the effect of using a textured insole (T-insole) on symmetry of stance and gait. The T-insole positioned in the shoe of one limb creates discomfort that forces the user to shift the body weight to the other limb. Method: Three experiments were conducted to uncover the role of discomfort-inducing textured insoles (T-insoles) on symmetry of stance and gait. The first experiment (healthy subjects, N=8) was focused on demonstrating that using a T-insole alters the symmetry of static balance and gait. The second experiment (individuals with stroke, N= 8) was conducted to understand if the T-insole improves the asymmetry of balance and gait in individuals with stroke. The focus of the third experiment (healthy subjects, N=8) was on comparing the effects of different prototypes of the T-insole on altering the symmetry of balance and gait. Static balance and gait parameters were measured with the Balance Master® and GAITRite® systems, and subjective discomfort was assessed with a Visual Analog scale. Symmetry indexes were calculated and analyzed. Paired t-tests were used in Experiments 1 and 2 to compare between the conditions and one-way ANOVA was applied in Experiment 3 to compare the effects of prototypes. Results: Using a T-insole resulted in a decrease of gait velocity (p < 0.05) and increased asymmetry of gait parameters (p < 0.05) in healthy individuals (Experiment 1). When individuals with stroke used the T-insole, improvements in asymmetry of gait parameters (p < 0.05) were seen (Experiment 2). The use of different prototypes was associated with variations in the observed changes in gait and stance symmetry: the T-insole prototype with redesigned projections was more effective as compared to other prototypes (p < 0.05). Conclusions: The outcome of the study demonstrates that a discomfort-inducing insole could alter stance and gait symmetry. Specifically, while using the T-insole, individuals with stroke were able to improve the symmetry of their gait. While all studied T-insoles could help in restoration of gait and stance symmetry, it is important to use the insole that produces the best possible effect.