Cost-Benefit of Muscle Cocontraction in Protecting Against Spinal Instability

Details

• Personal Author:
  Granata KP ; Marras WS
• Description:
  STUDY DESIGN: Lifting dynamics and electromyographic activity were evaluated using a biomechanical model of spinal equilibrium and stability to assess cost-benefit effects of antagonistic muscle cocontraction on the risk of stability failure. OBJECTIVES: To evaluate whether increased biomechanical stability associated with antagonistic cocontraction was capable of stabilizing the related increase in spinal load. SUMMARY OF BACKGROUND DATA: Antagonistic cocontraction contributes to improved spinal stability and increased spinal compression. For cocontraction to be considered beneficial, stability must increase more than spinal load. Otherwise, it may be possible for cocontraction to generate spinal loads that cannot be stabilized. METHODS: A biomechanical model was developed to compute spinal load and stability from measured electromyography and motion dynamics. As 10 healthy men performed sagittal lifting tasks, trunk motion, reaction loads, and electromyographic activities of eight trunk muscles were recorded. Spinal load and stability were evaluated as a function of cocontraction and trunk flexion angle. Stability was quantified in terms of the maximum spinal load the system could stabilize. RESULTS: Cocontraction was associated with a 12% to 18% increase in spinal compression and a 34% to 64% increase in stability. Spinal load and stability increased with trunk flexion. CONCLUSIONS: Despite increases in spinal load that had to be stabilized, the margin between stability and spinal compression increased significantly with cocontraction. Antagonistic cocontraction was found to be most beneficial at low trunk moments typically observed in upright postures. Similarly, empirically measured antagonistic cocontraction was recruited less in high-moment conditions and more in low-moment conditions. [Description provided by NIOSH]
• Subjects:
  Biomechanical Phenomena Musculoskeletal Diseases Musculoskeletal System Occupational Health Safety
• Keywords:
  Back Injuries Biomechanics Manual Lifting Manual Materials Handling Muscular Disorders Musculoskeletal System Musculoskeletal System Disorders Neuromuscular System Neuromuscular System Disorders Posture Spinal Disorders Spinal Stability Spine

  More +
• ISSN:
  0362-2436
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  25
• Issue:
  11
• NIOSHTIC Number:
  nn:20029820
• Citation:
  Spine 2000 Jun; 25(11):1398-1404
• Contact Point Address:
  Kevin P Granata, PhD, Motion Analysis and Motor Performance Laboratory, Kluge Children's Rehabilitation Center, University of Virginia, 2270 Ivy Road, Charlottesville, VA 22903
• Email:
  kpg8n@virginia.edu
• Federal Fiscal Year:
  2000
• NORA Priority Area:
  Disease and Injury: Low Back Disorders
• Performing Organization:
  Motion Analysis and Motor Performance Laboratory, Kluge Children's Rehabilitation Center, University of Virginia, Charlottesville VA
• Peer Reviewed:
  False
• Start Date:
  19970930
• Source Full Name:
  Spine
• End Date:
  20000929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:2a97308d20a1bbd6d4ef413a3984c8cecd147d030d045261bd464b7d7d9717380896b51bf8da30aa96df7c0423c7dde9d2929e4acf0f4b9faf31eba5ee1374e4
• Download URL:
  https://stacks.cdc.gov/view/cdc/190727/cdc_190727_DS1.pdf
• File Type:
  [PDF - 221.88 KB ]