Spectral Analysis of Impact Shock during Running

Abstract

The purpose of this study was to determine the effects of increasing impact shock levels on the spectral characteristics of impact shock and impact shock wave attenuation in the body during treadmill running. Twelve male subjects ran at 2.0, 3.0, 4.0, and 5.0 m s −1 on a treadmill. Axial accelerations of the shank and head were measured using low-mass accelerometers. The typical shank acceleration power spectrum contained two major components which corresponded to the active (5–8 Hz) and impact (12–20 Hz) phases of the time-domain ground reaction force. Both the amplitude and frequency of leg shock transients increased with increasing running speed. Greatest attenuation of the shock transmitted to the head occurred in the 15–50 Hz range. Attenuation increased with increasing running speed. Thus transmission of the impact shock wave to the head was limited, despite large increases in impact shock at the lower extremity.