Short Rest Between Cyclic Flexion Periods Is a Risk Factor for a Lumbar Disorder

Details

• Personal Author:
  Hoops H ; Lu Y ; Patel V ; Solomonow M ; Zhou BH
• Description:
  BACKGROUND: The epidemiology identifies cyclic lumbar loading as a risk factor for cumulative trauma disorder. Experimental biomechanical and physiological confirmation is lacking. The objective of this study was to asses the impact of different rest durations applied between periods of cyclic loading on the development of an acute lumbar disorder which, if continued to be subjected to loading, may develop into a cumulative disorder. METHODS: Three groups of in vivo feline preparations were subjected to six sequential 10 min loading periods of cyclic lumbar flexion at 40 N with a frequency of 0.25 Hz applied to the L-4/5 level. The rest durations varied from 5 min in the first group, to 10 min in the second and to 20 min in the third. Reflexive EMG from the multifidi and lumbar displacement were used to identify significant (P<0.001) effects of time and rest duration for post-load EMG and displacement. Single-cycle test were performed hourly for 7 h post-loading to assess recovery. A model developed earlier was applied to represent the experimental data. FINDINGS: The groups allowed 5 and 10 min rest exhibited an acute neuromuscular disorder expressed by a significant (P<0.001) delayed hyperexcitability 2-3 h into the 7 h recovery period with the intensity of the hyperexcitability significantly higher (P<0.001) for the group allowed only 5 min rest. The group allowed 20 min rest had a slow, uneventful recovery, free of delayed hyperexcitability. INTERPRETATIONS: Occupational and sports activities requiring repetitive (cyclic) loading of the lumbar spine may be a risk factor for the development of a cumulative lumbar disorder and may require sufficient rest, as much as twice as long as the loading period, for prevention. Comparison to similar data for static lumbar loading shows that cyclic loading is more deleterious than static loading, requiring more rest to offset the negative effect of the repeated acts of stretch. [Description provided by NIOSH]
• Subjects:
  Animals Biomechanical Phenomena Cumulative Trauma Disorders Epidemiology Fatigue Laboratories Musculoskeletal Diseases Nervous System Nervous System Diseases Occupational Health Safety

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• Keywords:
  Animal-studies Back-injuries Biomechanics Cumulative-trauma-disorders Laboratory-animals Laboratory-testing Musculoskeletal-system-disorders Neuromuscular-system-disorders Physiological-effects Physiological-factors Physiological-fatigue Physiological-measurements Physiological-response Rest-periods

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• ISSN:
  0268-0033
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Louisiana ; OSHA Region 6
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  22
• Issue:
  7
• NIOSHTIC Number:
  nn:20033018
• Citation:
  Clin Biomech 2007 Aug; 22(7):745-757
• Contact Point Address:
  Moshe Solomonow, Musculoskeletal Disorders Research Laboratory, Bioengineering Division, Department of Orthopedics, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
• Federal Fiscal Year:
  2007
• Performing Organization:
  Louisiana State University, Health Sciences Center, New Orleans, Louisiana
• Peer Reviewed:
  True
• Start Date:
  20000501
• Source Full Name:
  Clinical Biomechanics
• End Date:
  20031030
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4de2291006954f2fe4f7d6a48b2312eb7e0c9d3cf0e3da89bcb65a97faf312e89e7672297724c0b9479929f5d923a46399922a618c34c11fa15aa2fc570eb59e
• Download URL:
  https://stacks.cdc.gov/view/cdc/188753/cdc_188753_DS1.pdf
• File Type:
  [PDF - 618.02 KB ]