Effects of handicraft sitting postures on lower trunk muscle fatigue
The purpose of this study was to assess trunk muscle fatigue in seated handicraft tasks using surface electromyography (sEMG) and visual analogue scale (VAS) ratings for trunk discomfort, and to assess the relationship of these responses. Twenty-three participants were randomly assigned
to assumed crossed-leg and heel sitting postures for 30 min. Normalised median frequency (NMF) slopes for lumbar multifidus (LM) and internal oblique (IO) muscles and VAS ratings were recorded. Results revealed that the crossed-leg posture produced significantly steeper NMF slopes for
both sides of the LM and IO muscles than heel sitting. Greater VAS ratings were found in crossed-leg sitting posture than the heel sitting posture. The NMF slopes and the VAS ratings had significant negative correlations for both postures. Findings support heel sitting in handicraft tasks
over crossed-leg sitting due to greater trunk muscle fatigue and discomfort during the latter posture. Results support VAS ratings as a complementary method to sEMG for identifying trunk muscle fatigue.
Practitioner Summary: Trunk muscle fatigue in handicraft work is a potential
risk for low back pain. Based on EMG and discomfort analyses, heel sitting is preferred to crossed-leg posture. Discomfort ratings are consistent with EMG measures in identifying trunk muscle fatigue in such postures.
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normalised median frequency slope;
trunk muscle fatigue;
visual analogue scale
Document Type: Research Article
Department of Physical Therapy,Khon Kaen University, Khon Kaen, Thailand
Back, Neck and Other Joint Pain Research Group,Khon Kaen University, Khon Kaen, Thailand
Edward P. Fitts Department of Industrial & Systems Engineering,North Carolina State University, NC, USA
Department of Physiology, Faculty of Medicine,Khon Kaen University, Khon Kaen, Thailand
June 1, 2012
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