Journal of Korean Society of Industrial and Systems Engineering (산업경영시스템학회지)

Society of Korea Industrial and System Engineering (한국산업경영시스템학회)
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The Analysis of Low Back Loading and Muscle Fatigue while Lifting an Asymmetric Load

비대칭무게중심을 지닌 물체 들기 작업시 허리부위 등근육 부하 및 피로 분석

  • Han, Seung-Jo (Department of Industrial Engineering, Dankook University) ;
  • Kim, Sun-Uk (Department of Industrial Engineering, Dankook University)
  • 한승조 (단국대학교 공학대학 산업공학과) ;
  • 김선욱 (단국대학교 공학대학 산업공학과)
  • Received : 2012.03.02
  • Accepted : 2012.05.14
  • Published : 2012.06.30
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Abstract

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phenomenon with an experiment. Ten male subjects are required to lift and hold an given external load at 70cm height during 50sec, then the EMG amplitude and median frequency on bilateral low back muscle groups (Longissimus, Iliocostalis, and Multifidus) are recorded and analyzed. Independent variables are two-level load weight (13kg, 20kg) and three-level LCG (Center, 6.5cm to the right, and 13cm to the right), and dependent variables are EMG amplitude average, difference, and Fatigue Index (FI). Results show that load weight increases significantly amplitude average and FI, but LCG does significantly amplitude difference and FI significantly (P-value < 0.05). Also the correlation coefficient between amplitude difference and FI is over 0.99. These implies that trunk loading should be explained by not EMG amplitude but muscle fatigue aspect since the association between an external load and amplitude is linear, but the relationship between an external load and median frequency as muscle fatigue index is almost exponential.

Keywords

References

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