Determination of Gait events using an externally mounted shank accelerometer

Abstract

Biomechanical analysis requires the determination of specific foot contact events. This is typically achieved using force platform information, however when force platforms are unavailable, alternative methods are necessary. A method was developed for the determination of gait events using an accelerometer mounted to the distal tibia, measuring axial accelerations. The aim of the investigation was to determine the efficacy of this method. Sixteen participants ran at 4.0m.s-1 ±5 %. Synchronized axial tibial accelerations and vertical ground reaction forces were sampled at 1000 Hz as participants struck a force platform with their dominant foot. Events determined using the accelerometer were compared to the corresponding events determined using the force platform. Mean errors for heel strike events of 1.68 and 5.46 ms for average and absolute errors respectively. For toe-off events average and absolute errors of -3.59 and 5.00 ms were calculated. Mean and absolute errors of 5.18 and 11.47 ms were also found for the duration of the stance phase. Strong correlations r=0.96 were also observed between duration of stance obtained using the two different methods. The error values compare favourably to other alternative methods of predicting gait events. This suggests that shank mounted accelerometers can be used to accurately and reliably detect gait events.