Age Affects Skeletal Muscle Adaptation to Repeated Exposures of Stretch-Shortening Contractions

Details

• Personal Author:
  Alway SE ; Baker BA ; Cutlip, Robert G. ; Geronilla KB ; Kashon ML ; Murlasits Z
• Description:
  Previous studies have shown that skeletal muscle is more susceptible to contraction-induced injury and recovers more slowly after the initial injury in aged animals. Purpose: To investigate if aging affects the ability of skeletal muscle to adapt to repeated exposures of maximal stretch-shortening cycles (SSCs). Methods: Dorsiflexor muscles of old (30 months, N= 5) and young (12 weeks, N = 6) Fischer 344 × Brown Norway rats were exposed 3 times per week for 4.5 weeks to a protocol of 80 maximal stretch-shortening cycles (60 deg/s, 50 deg range of motion) per exposure in vivo. Performance was characterized by isometric performance, negative, positive, and net work, and stretch-shortening parameters (peak force and minimum force at each exposure interval (fourteen exposures). Results: The isometric force (p = 0.455), peak force (p = 0.761), and minimum force (p = 0.853) was not statistically different between groups at the start of the exposure. During the chronic exposure, those forces responded differently with age (p = 0.0003, 0.0081, and 0.0011 respectively) and were significantly different with age at the end of the exposure period (p <0.0001 for all parameters). Negative work and positive work were also not different between groups at the start of the exposure (p = 0.455 and 0.475, respectively). During the chronic exposure, both negative and positive work responded differently with age (p = 0.0044 and 0.0011, respectively) and resulted in significantly different magnitudes at the end of the exposure period (p <0.0011 for both parameters). There was also a significant increase in all performance parameters from the initial to the final exposure in the young animals (p <0.05), but a concomitant decrease in the old animals in all parameters (p <0.05) except negative work. Conclusions: A chronic exposure of SSCs results in a significant performance increase in young animals, and significant performance decrease in old animals. These findings indicate that aging impairs the ability of skeletal muscle to adapt to repetitive mechanical loading. [Description provided by NIOSH]
• Subjects:
  Age Factors Animals Environmental Monitoring Laboratories Musculoskeletal System Occupational Exposure Occupational Health Safety
• Keywords:
  Age-factors Animal-studies Chronic-exposure Exposure-assessment Exposure-levels In-vivo-studies Injuries Laboratory-animals Muscles Musculoskeletal-system Skeletal-system

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• ISSN:
  0195-9131
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; 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:
  37
• NIOSHTIC Number:
  nn:20027896
• Citation:
  Med Sci Sports Exerc 2005 Jun; 37(Suppl 5):S318
• Email:
  rgc8@cdc.gov
• Federal Fiscal Year:
  2005
• 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
• Supplement:
  5
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a0732901a9eee5322ed9c8a01e6d647db3b4bd63693e04ae53c12f4956e6d9eaed9e6289615c87fb2ad407dadbe85e498ea0683773dd5a45d77eedcbf6c50b00
• Download URL:
  https://stacks.cdc.gov/view/cdc/189661/cdc_189661_DS1.pdf
• File Type:
  [PDF - 449.30 KB ]