Low-frequency accelerations over-estimate impact-related shock during walking.
During gait, a failure to acknowledge the low-frequency component of a segmental acceleration signal will result in an overestimation of impact-related shock and may lead to inappropriately drawn conclusions. The present study was undertaken to investigate the significance of this low-frequency component in two distinctly different modalities of gait: barefoot (BF) and shod (SHOD) walking. Twenty-seven participants performed five walking trials at self-selected speed in each condition. Peak positive accelerations (PPA) at the shank and spine were first derived from the time-domain signal. The raw acceleration signals were then resolved in the frequency-domain and the active (low-frequency) and impact-related components of the power spectrum density (PSD) were quantified. PPA was significantly higher at the shank (P<0.0001) and spine (P=0.0007) in the BF condition. In contrast, no significant differences were apparent between conditions for shank (P=0.979) or spine (P=0.178) impact-related PSD when the low-frequency component was considered. This disparity between approaches was due to a significantly higher active PSD in both signals in the BF condition (P<0.0001; P=0.008, respectively), due to kinematic differences between conditions (P<0.05). These results indicate that the amplitude of the low-frequency component of an acceleration signal during gait is dependent on knee and ankle joint coordination behaviour, and highlight that impact-related shock is more accurately quantified in the frequency-domain following subtraction of this component.
Sport & Exercise Science and Nutrition Research Centre, Department of Applied Sciences, London South Bank University, London, UK. Electronic address: jamesd6@lsbu.ac.uk.
Darren C
DC
James
Sport & Exercise Science and Nutrition Research Centre, Department of Applied Sciences, London South Bank University, London, UK.
Katya N
KN
Mileva
Sport & Exercise Science and Nutrition Research Centre, Department of Applied Sciences, London South Bank University, London, UK.
David P
DP
Cook
D000054:Acceleration; D000328:Adult; D000843:Ankle Joint; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D012775:Shoes; D016138:Walking / Q000502:physiology*; D055815:Young Adult
Barefoot; Gait; Heel-strike; Kinematics; Shock