Reproducibility of loading measurements with skin-mounted accelerometers during walking

OBJECTIVE: To examine reproducibility of load measurements with skin-mounted accelerometers (SMAs) during walking. DESIGN: Reliability study. SETTING: A motion analysis laboratory. PARTICIPANTS: Ten healthy young men. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Two triaxial accelerometers were fixed to the subjects' skin above and below the knee joint. The subjects walked barefoot at their preferred speed and at a constant speed (1.3m/s, +/-5%) in a gait laboratory and along a corridor. The same protocol was repeated over 2 days. Initial peak acceleration (IPA), peak-to-peak (PP) acceleration, and maximal and average acceleration transient rates (ATRs) were calculated. The coefficient of variation (CV) and Pearson linear correlation coefficient were calculated to measure reproducibility of SMA load measurements. RESULTS: IPA and PP acceleration had good interday repeatability (CV <15%). The repeatability of average ATR and maximal ATR parameters was generally not acceptable. The loading variables obtained from ground reaction forces and SMA measurements during gait revealed high linear correlations, indicating that with SMA measurements it is possible to predict certain ground reaction force loading parameters. CONCLUSIONS: SMAs are practical for use in clinical environments to collect acceleration data that may be used to estimate joint loads.