한국산업보건학회지 (Journal of Korean Society of Occupational and Environmental Hygiene)

  • 제22권3호
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  • Pages.257-264
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  • 2012
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  • 2384-132X(pISSN)
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  • 2289-0564(eISSN)
한국산업보건학회 (Korean Industrial Hygiene Association)
권호 표지

중량물 들기 작업시 물체 무게중심 및 발의 위치가 허리 근육의 최대 EMG 진폭에 미치는 영향

Effects of Load Center of Gravity and Feet Positions on Peak EMG Amplitude at Low Back Muscles While Lifting Heavy Materials

  • 김선욱 (단국대학교 산업공학과) ;
  • 한승조 (단국대학교 산업공학과)
  • Kim, Sun-Uk (Industrial Engineering Department, Dankook University) ;
  • Han, Seung Jo (Industrial Engineering Department, Dankook University)
  • 발행 : 2012.09.30
⟨ 이전 논문 다음 논문 ⟩

초록

Objectives: This study's aims were to evaluate the effects of load center of gravity within an object lifted and feet placements on peak EMG amplitude acting on bilateral low back muscle groups, and to suggest adequate foot strategies with an aim to reducing low back pain incidence while lifting asymmetric load. Methods: The hypotheses that asymmetric load imposes more peak EMG amplitude on low back muscles contralateral to load center of gravity than symmetric load and maximum peak EMG amplitude out of bilateral ones can be relieved by locating one foot close to load center of gravity in front of the other were established based on biomechanics including safety margin model and previous researches. 11 male subjects were required to lift symmetrically a 15.8kg object during 2sec according to each conditions; symmetric load-parallel feet (SP), asymmetric load-parallel feet (AP), asymmetric load-one foot contralateral to load center of gravity in front of the other (AL), and asymmetric load-one foot ipsilateral to load center of gravity in front of the other (AR). Bilateral longissimus, iliocostalis, and multifidus on right and left low back area were selected as target muscles, and asymmetric load had load center of gravity 10cm deviated to the right from the center in the frontal plane. Results: Greater peak EMG amplitude in left muscle group than in right one was observed due to the effect of load center of gravity, and mean peak EMG amplitudes on both sides was not affected by load center of gravity because of EMG balancing effect. However, the difference of peak EMG amplitudes between both sides was significantly affected by it. Maximum peak EMG amplitude out of both sides and the difference of peak EMG amplitude between both sides could be reduced with keeping one foot ipsilateral to load center of gravity in front of the other while lifting asymmetric load. Conclusions: It was likely that asymmetric load lead to the elevated incidence of low back pain in comparison with symmetric load based on maximum peak EMG amplitude occurrence and greater imbalanced peak EMG amplitude between both sides. Changing feet positions according to the location of load center of gravity was suggested as one intervention able to reduce the low back pain incidence.

키워드

참고문헌

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