Capability and Recruitment Patterns of Trunk During Isometric Uniaxial and Biaxial Upright Exertion

Details

• Personal Author:
  Nordin M ; Parnianpour M ; Sheikhzadeh A
• Description:
  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. [Description provided by NIOSH]
• Subjects:
  Biomechanical Phenomena Ergonomics Musculoskeletal Diseases Musculoskeletal System Occupational Health Risk Assessment Risk Factors Safety
• Keywords:
  Back-injuries Biomechanics Humans Mathematical-models Musculoskeletal-system-disorders Posture Risk-analysis Risk-factors
• ISSN:
  0268-0033
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  New York ; OSHA Region 2
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  23
• Issue:
  5
• NIOSHTIC Number:
  nn:20034584
• Citation:
  Clin Biomech 2008 Jun; 23(5):527-535
• Contact Point Address:
  Ali Sheikhzadeh, The Occupational and Industrial Orthopaedic Center and Program of Ergonomics and Biomechanics, New York University, NYU Hospital for Joint Diseases, 63 Downing Street, New York, NY 10014
• Email:
  ali.sheikhzadeh@nyu.edu
• Federal Fiscal Year:
  2008
• NORA Priority Area:
  Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
• Performing Organization:
  Hospital for Joint Diseases Ortho Inst, New York, New York
• Peer Reviewed:
  True
• Start Date:
  19930801
• Source Full Name:
  Clinical Biomechanics
• End Date:
  19950731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7b5e81025c12f1fdd8826f61f1e3a797d5736c475e594a8dde54d80fd1ded9aa28f57587734ba7ae7e703018b873f296863aca96f7d09f1fb9194d5cafe053d8
• Download URL:
  https://stacks.cdc.gov/view/cdc/186741/cdc_186741_DS1.pdf
• File Type:
  [PDF - 188.55 KB ]