Neural control of posture during small magnitude perturbations: effects of aging and localized muscle fatigue

Details

• Personal Author:
  Davidson BS ; Madigan ML ; Nussbaum MA ; Southward SC
• Description:
  This study investigated the effects of aging and localized muscle fatigue on the neural control of upright stance during small postural perturbations. Sixteen young (aged 18-24 years) and 16 older (aged 55-74 years) participants were exposed to small magnitude, anteriorly-directed postural perturbations before and after fatiguing exercises (lumbar extensors and ankle plantar flexors). A single degree of freedom model of the human body was used to simulate recovery kinematics following the perturbations. Central to the model was a simulated neural controller that multiplied time-delayed kinematics by invariant feedback gains. Feedback gains and time delay were optimized for each participant based on measured kinematics, and a novel delay margin analysis was performed to assess system robustness. A 10.9 percent longer effective time delay ( p = 0.010) was found among the older group, who also showed a greater reliance upon velocity feedback information (31.1 percent higher differential gain, p = 0.001) to control upright stance. Based on delay margins, older participants adopted a more robust control scheme to accommodate the small perturbations, potentially compensating for longer time delays or degraded sensory feedback. No fatigue-induced changes in neural controller gains, time delay, or delay margin were found in either age group, indicating that integration of this feedback information was not altered by muscle fatigue. The sensitivity of this approach to changes with fatigue may have been limited by model simplifications. [Description provided by NIOSH]
• Subjects:
  Age Factors Aging Biomechanical Phenomena Fatigue Musculoskeletal System Occupational Health Safety Sense Organs
• Keywords:
  Age-factors Age-groups Biomechanics Feedback-controls Humans Motion-studies Muscle-function Muscles Musculoskeletal-system Physical-exercise Physiological-fatigue Posture Sensory-motor-system Simulation-methods

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• ISSN:
  0018-9294
• 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:
  58
• Issue:
  6
• NIOSHTIC Number:
  nn:20039653
• Citation:
  IEEE Trans Biomed Eng 2011 Jun; 58(6):1546-1554
• Contact Point Address:
  Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
• Email:
  bradley.davidson@du.edu
• Federal Fiscal Year:
  2011
• Performing Organization:
  Virginia Polytechnic Institute and State University
• Peer Reviewed:
  True
• Start Date:
  20030901
• Source Full Name:
  IEEE Transactions on Biomedical Engineering
• End Date:
  20080831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:34daaffd82caad68561a56e4518f27a4ca464e8141e0086872c1fbbf09d25eeba3532a3508368f0a615237b5e433d4528679f7628fd9584edca988a0de569750
• Download URL:
  https://stacks.cdc.gov/view/cdc/192820/cdc_192820_DS1.pdf
• File Type:
  [PDF - 629.11 KB ]