Effects of Range of Motion on Skeletal Muscle Morphology Due to Stretch-Shortening Cycle-Induced Injury

Details

• Personal Author:
  Baker BA ; Cutlip, Robert G. ; Geronilla KB ; Krajnak, Kristine M. ; Mercer R ; Miller, G. Roger
• Description:
  Quantification of skeletal muscle damage in response to injurious stretch-shortening cycles (SSC's) would be beneficial in elucidating the effect of different biomechanical exposures on the amount of muscle damage. Purpose: To investigate the effect of stretch-shortening cycle range of motion (ROM) on skeletal muscle damage in rats. Methods: Testing was performed on the dorsiflexor muscles of Sprague-Dawley rats in vivo. Animals (n = 36) were randomly assigned to a long ROM injury group (L-Inj), short ROM injury group (S-Inj), or isometric group (Iso). The injury protocol consisted of 7 sets of 10 SSC's at 500 degrees/s. The S-Inj group received SSC's between 70 degrees-120 degrees ankle angle, whereas the L-Inj group received SSC's between 90 degrees-140 degrees ankle angle. The Iso group received equivalent muscle stimulation at 90 degrees ankle angle. Dorsiflexor muscles were stimulated for 2.8 s each set and administered every minute. Rats were sacrificed at 6 and 48 hours post exposure. Following sacrifice, tissue was excised, weighed, sectioned, quick-frozen, and stored at -80 degrees C. Transverse sections (12 microm) were cut, mounted on pre-coated microscope slides, and stained using a routine procedure with Harris Hematoxylin & Eosin. Tissue sections were evaluated on a Leica DMLB microscope. Stereology was used to quantify the degree of myofiber damage in muscle from each group; and, also was used to measure the volume fraction, surface densities, and average thickness of normal myofibers, degenerative myofibers, and the interstitial space. Results: No degenerative fibers were present in the contra-lateral control tissue, Iso group at 6h or 48h post-injury, nor the S-inj and L-inj at 6h post injury. In contrast, there was an increased volume of degenerative myofibers in the S-inj and L-inj at 48h post injury. The volume of cellular interstitium (cell infiltrates) and non-cellular interstitium (edema) increased (p = 0.0082 and p = 0.0053; respectively) from muscle exposed to the S-inj and L-inj at 48h post injury; and, thus the average thickness of the extracellular matrix increased with these groups. Conclusions: Increased degenerative myofibers, cellular infiltrates, and edema occur temporally in response to both S-inj and L-inj. However, a more dramatic increase occurs with the L-inj at 48h as assessed by the increase in volume of cellular and non-cellular interstitium. [Description provided by NIOSH]
• Subjects:
  Accident Prevention Accidents Geology Mining Occupational Health Safety
• Keywords:
  Animal-studies Animals Laboratory-animals Muscle-function Muscle-physiology Muscle-tissue Musculoskeletal-system Physiological-effects Physiology
• ISSN:
  0195-9131
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Indiana ; OSHA Region 3 ; OSHA Region 5 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  36
• NIOSHTIC Number:
  nn:20025567
• Citation:
  Med Sci Sports Exerc 2004 May; 36(Suppl 5):S2
• Email:
  bwb3@cdc.gov
• Federal Fiscal Year:
  2004
• NORA Priority Area:
  Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
• Peer Reviewed:
  False
• Source Full Name:
  Medicine and Science in Sports and Exercise. American College of Sports Medicine, 51st Annual Meeting, Indianapolis, Indiana, June 2-5, 2004
• Supplement:
  5
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:c0541b80a5c54b3adfb306e9f6a526790f889d2a24120cf6d1a7ffc077bdd6e1afeba94f0a7546837e7175049e2ce539710ba6b9ebc73dc226ba3aaeb58f6a29
• Download URL:
  https://stacks.cdc.gov/view/cdc/196867/cdc_196867_DS1.pdf
• File Type:
  [PDF - 39.28 KB ]