The Effect of Maximum Voluntary Contraction on Endurance Times for the Shoulder Girdle

Details

• Personal Author:
  Garg, Arun ; Hegmann KT ; Kapellusch JM ; Schwoerer BJ
• Description:
  This study investigated endurance times as percentages of maximum voluntary contractions (MVCs) in 12 healthy females (mean 25.874.3 years) in 5 postures and at 7% MVCs. The shoulder postures utilized were 30/90 (shoulder forward flexion=301 and included elbow angle=901), 60/90, 90/120, 120/150, and 150/180.The %MVCs were 5%, 15%, 30%, 45%, 60%, 75%, and 90% of MVC at each of these postures.Outcome measures included: endurance times, ratings of perceived exertion, fatigue ratings, pain ratings, and surface electromyography (trapezius and middeltoid). As expected the endurance time decreased non-linearly with an increase in %MVC.However, the relationship between endurance time and %MVC differed significantly from Rohmert's curve and suggests it considerably overestimates endurance times for %MVCs o45% and it underestimates endurance times for %MVCs >45%.This study's curve did not become asymptotic even at 5% MVC.Shoulder posture (shoulder forward flexion angle) had a significant effect on endurance time.In general, endurance time decreased with an increase in shoulder flexion angle up to 1201 and then it increased.Thus, overhead work (hands above the head) would appear to be better designed with a greater degree of forward flexion, rather than in front of the worker at lower degrees of forward flexion. [Description provided by NIOSH]
• Subjects:
  Ergonomics Fatigue Musculoskeletal Diseases Musculoskeletal System Occupational Health Safety Women
• Keywords:
  Author Keywords: Endurance Electromyography Endurance-tests Muscle-contraction Muscle-stress Musculoskeletal-system Pain-tolerance Physical-capacity Posture Rohmert's Curve Shoulder Shoulder Girdle

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• ISSN:
  0169-8141
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 5 ; OSHA Region 8 ; Utah ; Wisconsin
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  103-113
• Volume:
  30
• Issue:
  2
• NIOSHTIC Number:
  nn:20037558
• Citation:
  Int J Ind Ergon 2002 Aug; 30(2):103-113
• Contact Point Address:
  A.Garg, Department of Industrial and Manufacturing Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
• Email:
  arun@uwm.edu
• Federal Fiscal Year:
  2002
• Performing Organization:
  University of Utah
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  International Journal of Industrial Ergonomics
• End Date:
  20280630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:fce0bc356d0f9613b8c96ef4c7c125a0fe11a3592b0c4982013b88fb01a34a9b6585ea5ec888502d0feafdc7b25356948ded6a599508d68fa30a6519ad073f67
• Download URL:
  https://stacks.cdc.gov/view/cdc/188634/cdc_188634_DS1.pdf
• File Type:
  [PDF - 181.83 KB ]