Performance of repetitive tasks induces decreased grip strength and increased fibrogenic proteins in skeletal muscle: role of force and inflammation

Details

• Personal Author:
  Abdelmagid SM ; Amin M ; Barbe MF ; Barr AE ; Litvin J ; Popoff SN ; Rico M ; Safadi FF
• Description:
  BACKGROUND: This study elucidates exposure-response relationships between performance of repetitive tasks, grip strength declines, and fibrogenic-related protein changes in muscles, and their link to inflammation. Specifically, we examined forearm flexor digitorum muscles for changes in connective tissue growth factor (CTGF; a matrix protein associated with fibrosis), collagen type I (Col1; a matrix component), and transforming growth factor beta 1 (TGFB1; an upstream modulator of CTGF and collagen), in rats performing one of two repetitive tasks, with or without anti-inflammatory drugs. METHODOLOGY/RESULTS: To examine the roles of force versus repetition, rats performed either a high repetition negligible force food retrieval task (HRNF), or a high repetition high force handle-pulling task (HRHF), for up to 9 weeks, with results compared to trained only (TR-NF or TR-HF) and normal control rats. Grip strength declined with both tasks, with the greatest declines in 9-week HRHF rats. Quantitative PCR (qPCR) analyses of HRNF muscles showed increased expression of Col1 in weeks 3-9, and CTGF in weeks 6 and 9. Immunohistochemistry confirmed PCR results, and also showed greater increases of CTGF and collagen matrix in 9-week HRHF rats than 9-week HRNF rats. ELISA, and immunohistochemistry revealed greater increases of TGFB1 in TR-HF and 6-week HRHF, compared to 6-week HRNF rats. To examine the role of inflammation, results from 6-week HRHF rats were compared to rats receiving ibuprofen or anti-TNF-a treatment in HRHF weeks 4-6. Both treatments attenuated HRHF-induced increases in CTGF and fibrosis by 6 weeks of task performance. Ibuprofen attenuated TGFB1 increases and grip strength declines, matching our prior results with anti-TNFa. CONCLUSIONS/SIGNIFICANCE: Performance of highly repetitive tasks was associated with force-dependent declines in grip strength and increased fibrogenic-related proteins in flexor digitorum muscles. These changes were attenuated, at least short-term, by anti-inflammatory treatments. [Description provided by NIOSH]
• Subjects:
  Fibrosis Laboratories Musculoskeletal Diseases Musculoskeletal System Occupational Health Safety
• Keywords:
  Exposure-levels Fibrogenicity Force Hand-injuries Injuries Laboratory-animals Muscle-physiology Muscles Muscular-disorders Musculoskeletal-system Musculoskeletal-system-disorders Proteins Repetitive-work Skeletal-system Skeletal-system-disorders

  More +
• ISSN:
  1932-6203
• Document Type:
  Text
• Funding:
  Cooperative Agreement ; Grant
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; Oregon ; OSHA Region 10 ; OSHA Region 3 ; OSHA Region 5 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  7
• Issue:
  5
• NIOSHTIC Number:
  nn:20041397
• Citation:
  PLoS One 2012 May; 7(5):e38359
• Email:
  mary.barbe@temple.edu
• Federal Fiscal Year:
  2012
• Performing Organization:
  Temple University, Philadelphia, Pennsylvania
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  PLoS One
• End Date:
  20080630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:108cfb2d29cf0f2095f974aec927259961e4637932f5eaabe98b4327af29e9320b8252fd67a2e18f3a4d327d4e05840f6650aff76095fe25e89479a91dcc5b02
• Download URL:
  https://stacks.cdc.gov/view/cdc/193973/cdc_193973_DS1.pdf
• File Type:
  [PDF - 5.56 MB ]