Slip-related muscle activation patterns of the stance leg during gait

Details

• Personal Author:
  Chambers AJ
• Description:
  Falls precipitated by slipping are a major cause of injury, death and disability in the elderly. This research focused on muscle activation patterns generated in response to slipping and anticipation of slippery surfaces. The goal was to identify the muscle activation patterns of the stance leg in response to an unexpected slip (reactive strategies) and investigate muscle activity when anticipating slippery floors during gait on dry surfaces (proactive strategies). Additionally, age-related differences were examined. Electromyographic recordings were made from the Vastus Lateralis, Medial Hamstring, Tibialis Anterior and Medial Gastrocnemius of eleven young and nine older adults. Participants walked during the following conditions: (1) baseline dry (subjects knew the floor was dry); (2) unexpected slip (contaminant was applied to floor without subjects' knowledge); (3) alert dry (subjects were uncertain of the floor's condition). Reactive strategies, which were similar among young and older adults, consisted of activation of the Medial Hamstring at around 21% stance (approximately 175 ms) followed by the Vastus Lateralis at around 29% stance (approximately 240 ms). Corrective responses were scaled to slip severity with more severe slip reactions consisting of longer, higher magnitude responses. Delayed Vastus Lateralis latency and Medial Hamstring cessation were associated with an increased slip severity as quantified by peak slip velocity. Additionally, when experiencing a severe slip, young adults demonstrated a longer, more powerful response compared to older adults. Anticipation of a slippery surface resulted in increased magnitude of activation (48% increase) and ankle/knee co-contraction (30% increase), as well as earlier onsets and longer durations of posterior muscles. Young adults demonstrated earlier onsets (3% stance, 24 ms) and longer durations (10% stance, 83 ms) than older adults reducing their slip potential. Finally, adults with baseline gait on dry floors characterized by greater ankle co-contraction at heel contact and delayed Tibialis Anterior onset were predisposed to experience less severe slips when encountering an unexpected slippery floor. Older adults' natural gait predisposes them to experience a less hazardous slip. However, once a slip occurs, older adults cannot react with the long, powerful response needed to prevent balance loss whereas young adults are capable of this response. [Description provided by NIOSH]
• Subjects:
  Accidents, Occupational Aging Biomechanical Phenomena Musculoskeletal System Occupational Health Public Health Safety
• Keywords:
  Accidents Age-groups Biomechanics Floors Hazards Injuries Musculoskeletal-system Occupational-health Physiological-factors Physiological-function Physiological-response Public-health

  More +
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Report
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-99
• NIOSHTIC Number:
  nn:20039980
• Citation:
  Pittsburgh, PA: University of Pittsburgh, 2005 Jul; :1-99
• Federal Fiscal Year:
  2005
• NORA Priority Area:
  Work Environment and Workforce: Special Populations
• Performing Organization:
  University of Pittsburgh
• Peer Reviewed:
  False
• Start Date:
  20020801
• Source Full Name:
  Slip-related Muscle Activation Patterns of the Stance Leg during Gait
• End Date:
  20110831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ebd8b9696b15368e3dc0ad6414b55b32930d35423dede2ea0fff3c7decd145e6de0e3f48aeda1ac81807b557a79899fcac0a6339a7ecb0fd38ac51cd96f4ab19
• Download URL:
  https://stacks.cdc.gov/view/cdc/193004/cdc_193004_DS1.pdf
• File Type:
  [PDF - 1.20 MB ]