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J Electromyogr Kinesiol. 2014 Apr;24(2):264-70. doi: 10.1016/j.jelekin.2013.12.008. Epub 2014 Jan 9.

Low-frequency accelerations over-estimate impact-related shock during walking.

Author information

1
Sport & Exercise Science and Nutrition Research Centre, Department of Applied Sciences, London South Bank University, London, UK. Electronic address: jamesd6@lsbu.ac.uk.
2
Sport & Exercise Science and Nutrition Research Centre, Department of Applied Sciences, London South Bank University, London, UK.

Abstract

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.

KEYWORDS:

Barefoot; Gait; Heel-strike; Kinematics; Shock

PMID:
24485558
DOI:
10.1016/j.jelekin.2013.12.008
[Indexed for MEDLINE]
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