Role of Z-Coilª Shoes on Plantar Pressure Forces during Short Distance Walking

Purpose: The Z-CoiL ® company has marketed a shoe that is advertised to decrease pressure and attenuation of forces on the foot, ankle, and other lower extremity joints. Evidence based studies, however, are lacking in support of this claim. The purpose of this study was to compare the peak pressure distributed onto the bottom of the foot from heel strike to midstance when walking bare foot, using a personal athletic shoe, and using a Z-CoiL ® shoe. Subjects: Thirty subjects without any current history of orthopedic pathologies were examined in this study. Fourteen subjects were excluded from final data analysis, due to a ceiling effect of the pressure mapping insole. lf the calibrated pressure of 30 psi was reached 3 times in the heel region during the peak pressure reading, then the subject was excluded. Instrumentation: Peak-heel pressure measurements were taken while each subject walked in the respective footwear, using the Force Sensitive Application pressure mapping system. Data Analysis/Results: The time frame in the gait cycle with the highest heel pressure reading was used for analysis. The top nine sensor readings in this frame were averaged to determine an overall peak pressure in this region. A pilot study with 12 subjects established that the intra-class correlation coefficients for this method were \u3e0.85-0.97 in all cases for reliability as concluded by the SPSS program, using a covariance matrix method. A repeated single factor ANOVA was used to determine significant difference between the three conditions. Further post-hoc analysis revealed pair-wise significance between barefoot walking and Z-CoiL ® (p =0.001) and barefoot walking and the personal athletic shoes (p =0.002.) There was not significant difference between Z-CoiL ® and personal athletic shoes (p = 0.731). Conclusion/Clinical Implications: A significant difference in pressure was shown when comparing the sandal to the Z-CoiL ® shoe and the sandal to the personal athletic shoe. There was not a significant decrease in peak heel pressure between the Z-CoiL ® and personal athletic shoe. This study suggests that clear evidence supporting attenuation of pressure with Z-CoiL ® shoes is lacking. This study, however, had several limitations that may have contributed to inaccurate results, including the speed of gait and familiarity with the shoe type. Therefore, further studies are warranted prior to recommending Z-CoiL ® shoes for pressure relief