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Strategical Postures for Relieving EMG Amplitude Discrepancy on Bilateral Low Back Muscles and Total Low Back Muscle Fatigue while Lifting Asymmetric Load Dynamically  

Kim, Sun-Uk (Department of Industrial Engineering, Dankook University)
Han, Seung-Jo (Department of Industrial Engineering, Dankook University)
Publication Information
Journal of Korean Society of Industrial and Systems Engineering / v.35, no.3, 2012 , pp. 103-109 More about this Journal
Abstract
The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symmetrically an external load with 15.8kg and load center of gravity (LCG) deviated 10cm to the right from the floor to the waist height at the speed of about 25cm/sec. The EMG amplitudes on bilateral low back muscles (Longissimus, Iliocostalis, and Multifidus) are recorded during 2sec and analyzed. Independent variables are trunk postures (No bending vs. Bending to the LCG) and feet placements (Parallel vs. Right foot in front of the other vs. Right foot behind the other). Dependent variables are EMG amplitude average on six muscles and the EMG amplitude difference between right and left muscle group. Results indicate the phenomenon showing an amplitude increase in the left muscle group is equal to an decrease in the right one is observed in dynamic as well as static lifts, bending the trunk to the LCG increases amplitude discrepancy more than no trunk bending, and the amplitude discrepancy in one foot ipsilateral to LCG in front of the other foot is lowest among other foot postures. As bilateral EMG amplitude discrepancy increases total low back muscle fatigue, the strategical combination of no trunk bending and one foot close to LCG in front of the other is recommended for preventing elevated incidence of low back pain (LBP).
Keywords
Asymmetric Load; EMG Amplitude Discrepancy; Foot Posture; Dynamic Lifts; Trunk Lateral Bending;
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Times Cited By KSCI : 1  (Citation Analysis)
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