Capability and recruitment patterns of trunk during isometric uniaxial and biaxial upright exertion

Title
Capability and recruitment patterns of trunk during isometric uniaxial and biaxial upright exertion
Author
Parnianpour, Mohammad
Keywords
isometric trunk exertion; biomechanics; ergonomics; EMG; abdominal muscles; lumbar spine; low back
Issue Date
2008-06
Publisher
ELSEVIER SCI LTD
Citation
CLINICAL BIOMECHANICS, v. 23, No. 5, Page. 527-535
Abstract
Background. Work-related risk factors of low back disorders have been identified to be external moments, awkward postures, and asymmetrical dynamic lifting amongst others. The distinct role of asymmetry of load versus Posture is hard to discern from the literature. Hence, the aim of this study is to measure isometric trunk exertions at upright standing posture at different exertion level and degree of asymmetry to further delineate the effects of exertion level and asymmetry on neuromuscular capability response. Methods. Fifteen healthy volunteers randomly performed trunk exertions at three levels (30%, 60%, and 100% of maximum voluntary exertion and five different angles (0 degrees, 45 degrees, 90 degrees, 135 degrees, and 180 degrees) of normalized resultant moments. During each trial, the normalized EMG activity of 10 selected trunk muscles was quantified. Findings. The EMG activity of the 10 trunk muscles was significantly (P < 0.001) affected by the level of exertion and angle of normalized resultant moment, and their interactions. The controllability of the torque generation was reduced in biaxial exertions. The capability to generate and control the required trunk moments is significantly lowered during biaxial trunk exertions, while all muscles present higher EMG activity. These results suggest that the trunk muscles will be taxed higher while performing biaxial exertion tasks, increasing muscle fatigue possibly leading to a higher probability of low back injury. Interpretation. The prediction of biaxial trunk performance based on uniaxial data will result in an overestimation of capability and controllability of the trunk during physically demanding tasks. This study provides a better understanding of the potential mechanisms of injury during asymmetrical and biaxial trunk exertion during work-related tasks. (c) 2007 Elsevier Ltd. All rights reserved.
URI
https://www.sciencedirect.com/science/article/pii/S0268003307002720http://repository.hanyang.ac.kr/handle/20.500.11754/80520
ISSN
0268-0033
DOI
10.1016/j.clinbiomech.2007.11.017
Appears in Collections:
COLLEGE OF ENGINEERING SCIENCES[E](공학대학) > INDUSTRIAL AND MANAGEMENT ENGINEERING(산업경영공학과) > Articles
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