Quantifying foot inter-joint coordination and variability after wearing variable stiffness foot insoles during the stance phase of running

Although foot orthotics with different stiffness is widely used for the treatment of lower extremity abnormalities and injuries, but their effect on foot coordination and variability is unclear. The purpose of present study was to investigate the effect of different stiffness of shoe orthosis on foot inter-joint coordination pattern and variability during the stance phase of running. Fifteen healthy active men volunteered to participate in this study. Coordination pattern and variability were calculated from kinematics raw data using a Continuous Relative Phase method while running with different stiffness insoles inserted in a sandal. A repeated measure of ANOVA test was performed to test the hypothesis (p < 0.05). a part of the results showed that running with hard, soft, and semi-hard increased about %95, %179, and %220 of continue relative phase inversion: eversion of the ankle and tarsometatarsal joint in first 25% of stance phase compared to no insole condition (p < 0.001). Generally, the findings show that insole stiffness may affect lower extremity mechanics by changing foot inter-joint coordination and variability. Thus, insole stiffness should be considered when specialists use the orthotic devices for treatment.