The Use of Spectral Analysis to Assess the Performance of Shock Absorbing Footwear

Abstract

Spectral analysis methods have been used to examine the influence of shock absorbing inserts on heel strike transients in normal gait. The data were obtained from a piezoelectric accelerometer mounted on a custom moulded splint fitting around the malleoli which was found to eliminate unwanted resonances. The peak accelerations measured with this system were similar to those obtained in earlier studies. Examination of the gait of one subject in four different types of footwear showed that a reduction of rms acceleration could be achieved by the use of a shock absorbing insert. The efficiency of the insert was measured by its ability to reduce the rms acceleration in the 10–150 Hz band and to reduce the rms signal in the 50–150 Hz band as a proportion of the total. This second measure was defined as the ‘Shock Factor’.