Isometric and Concentric Performance of Electrically Stimulated Ankle Plantar Flexor Muscles in Intact Rat

Details

• Personal Author:
  Stauber WT ; Willems MET
• Description:
  The relationship between muscle force and ankle position during isometric and pre-loaded slow concentric contractions (angular velocity, 0.52 rad s-1; range of motion, 1.22 rad) and the recovery of isometric force following concentric contractions at different velocities were determined for electrically stimulated plantar flexor muscles in intact rats. Pre-loaded refers to the isometric contraction which immediately precedes the concentric contraction. Ankle position was controlled by a dynamometer and force was recorded under the sole of the foot. The peak isometric force (19.2 N) was nearly constant at all ankle positions (range of motion, 1.57 rad). The muscle length and distal fibre length of gastrocnemius medialis at ankle positions between 0.79 rad and 2.01 rad were increased by 12.6 % and 20.3 %, respectively. During slow concentric contractions, the force progressively decreased (23.1+/-2.1 %); the force decreased by only 6.3 +/-0.9% during sustained isometric contractions of similar duration (3400 ms). The recovery of isometric force following concentric contractions with similar stimulation frequencies (80 Hz) was velocity dependent (i.e. more rapid at higher velocities). It is concluded that pre-loaded slow concentric contractions of the plantar flexor muscles in intact rats do not follow the same relationship as that of isometric force and ankle position. Our results in intact rats show that the force output of electrically stimulated ankle plantar flexor muscles measured under the sole of the foot can be used to study the physiological properties of skeletal muscle working in situ. Description provided by NIOSH
• Subjects:
  • Animals
  • Laboratories
  • Musculoskeletal Diseases
  • Musculoskeletal System
  • Occupational Health
  • Safety
• Keywords:
  • Laboratory animals
  • Animals
  • Animal studies
  • Physiological testing
  • Skeletal disorders
  • Musculoskeletal system disorders
  • Muscle stress
• ISSN:
  0958-0670
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  379-389
• Volume:
  84
• Issue:
  2
• NIOSHTIC Number:
  nn:20024479
• Citation:
  Exp Physiol 1999 Mar; 84(2):379-389
• Email:
  wstauber@wvu.edu
• Federal Fiscal Year:
  1999
• NORA Priority Area:
  Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
• Performing Organization:
  West Virginia University, Morgantown, West Virginia
• Peer Reviewed:
  True
• Start Date:
  19920101
• Source Full Name:
  Experimental Physiology
• End Date:
  20050531
• Download URL:
  https://stacks.cdc.gov/view/cdc/196262/cdc_196262_DS1.pdf
• File Type:
  [PDF - 241.38 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:66f625b18020236754b0fd6863492eece7fdf8fa62659e2bab7c5d48dc8a18b0351cd8934c8e024a7134697e3e4f65b002ab647adeffbb1a64746095c61b9801