Shoe-mounted accelerometers should be used with caution in gait retraining

Real-time biofeedback gait retraining has been reported to be an effective intervention to lower the impact loading during gait. While many of the previous gait retraining studies have utilized a laboratory-based setup, some studies used accelerometers affixed at the distal tibia to allow training outside the laboratory environment. However, many commercial sensors for gait modification are shoe-mounted. Hence, this study sought to compare impact loading parameters measured by shoe-mounted and tibia sensors in participants before and after a course of walking or running retraining using signal source from the shoe-mounted sensors. We also compared the correlations between peak positive acceleration measured at shoe (PPA_S ) and tibia (PPA_T ) and vertical loading rates, as these loading rates have been related to injury. Twenty-four and 14 participants underwent a 2-week visual biofeedback walking and running retraining, respectively. Participants in the walking retraining group experienced lower PPA_S following the intervention (P < 0.005). However, they demonstrated no change in PPA_T (P = 0.409) nor vertical loading rates (P > 0.098) following the walking retraining. In contrast, participants in the running retraining group experienced a reduction in the PPA_T (P = 0.001) and vertical loading rates (P < 0.013) after running retraining. PPA_S values were four times that of PPA_T for both walking and running suggesting an uncoupling of the shoe with tibia. As such, PPA_S was not correlated with vertical loading rates for either walking or running, while significant correlations between PPA_T and vertical loading rates were noted. The present study suggests potential limitations of the existing commercial shoe-mounted sensors.