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Neuromuscular response to cyclic lumbar twisting.

Authors
Li-L; Patel-N; Solomonow-D; Le-P; Hoops-H; Gerhardt-D; Johnson-K; Zhou-BH; Lu-Y; Solomonow-M
Source
Hum Factors 2007 Oct; 49(5):820-829
NIOSHTIC No.
20032678
Abstract
OBJECTIVE: to study the influence of 10 min of cyclic twisting motion on abdominal and back muscle activities. BACKGROUND: repetitive (cyclic) occupational activity was identified by many epidemiological reports to be a risk factor for the development of work-related musculoskeletal disorders. Biomechanical and physiological confirmation, however, is lacking. METHODS: trunk muscle electromyography (EMG) was recorded while participants performed a continuous 10-min maximum lumbar cyclic twisting to the left, and maximum isometric twist to the left and right sides was measured before and after the exercise. RESULTS: abdominal muscles contracted symmetrically, independent of twisting direction. The left posterior muscles' integrated EMG (IEMG) decreased during the exercise, whereas the IEMG of the right posterior muscle increased. Simultaneously with increased antagonist coactivity level of the right posterior muscles after the exercise, decrease in maximal isometric left twisting torque was observed. The abdominal muscles did not exhibit any significant changes during the exercise. After the exercise, the right abdominals demonstrated a significant increase in effort, which was independent of the direction of the maximal effort isometric test. CONCLUSIONS: the change in muscle activity is attributed to neuromuscular compensation for the development of laxity and microdamage in the soft tissue (ligaments, discs, facet capsules, etc.) of the lumbar spine. APPLICATION: the results of this study increase understanding of the risk factors associated with low back disorder induced by labor-intensive occupations that involve cyclic lateral twisting.
Keywords
Biomechanics; Neuromuscular-system-disorders; Epidemiology; Demographic-characteristics; Etiology; Musculoskeletal-system-disorders; Musculoskeletal-system; Biomechanics; Physiological-factors; Repetitive-work; Physical-exercise; Neuromotor-function; Neuromuscular-function; Neuromuscular-system
Contact
Occupational Medicine Research Center, Bioengineering Laboratory, Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, 2025 Gravier Street, Suite 400, New Orleans, LA 70112
CODEN
HUFAA6
Publication Date
20071001
Document Type
Journal Article
Funding Amount
695194
Funding Type
Grant
Fiscal Year
2008
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-007622
Issue of Publication
5
ISSN
0018-7208
Source Name
Human Factors
State
LA
Performing Organization
Louisiana State University, Health Sciences Center, New Orleans, Louisiana
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