Measuring neuromuscular fatigue in cervical spinal musculature of military helicopter aircrew

Neck pain and muscle function in aircrew have received considerable attention. We hypothesized normalized electromyography (EMG) frequency would provide insight into appropriate methods to assess muscle fatigue in helicopter aircrew. 40 helicopter aircrew performed isometric testing that included ma...

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Bibliographic Details
Published in:Military medicine 2009-11, Vol.174 (11), p.1183-1189
Main Authors: Harrison, Michael F, Neary, J Patrick, Albert, Wayne J, Kuruganti, Usha, Croll, James C, Chancey, V Carol, Bumgardner, Bradley A
Format: Article
Language:English
Subjects:
Adult
Aircraft
Analysis of Variance
Electromyography
Female
Humans
Male
Military Personnel
Muscle Contraction - physiology
Muscle fatigue
Muscle Fatigue - physiology
Neck Muscles - physiopathology
Neck pain
Neck Pain - physiopathology
Occupational Diseases - physiopathology
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Summary:Neck pain and muscle function in aircrew have received considerable attention. We hypothesized normalized electromyography (EMG) frequency would provide insight into appropriate methods to assess muscle fatigue in helicopter aircrew. 40 helicopter aircrew performed isometric testing that included maximal voluntary contractions (MVC) and 70% MVC endurance protocols of extension, flexion, and left and right lateral flexion for cervical muscles. Bilateral muscle activity in the splenius capitis, sternocleidomastoid, and upper trapezius was monitored with EMG. Normalized mean EMG frequency was calculated for each muscle at the start and end of the 70% MVC trials to determine which muscles fatigued and limited force maintenance during each isometric movement. For extension, the left and right splenius capitis fatigued by approximately 21-22% (p < 0.01); for flexion, the left and right sternocleidomastoid fatigued by approximately 11-14% (p < 0.01); for right flexion, the right sternocleidomastoid fatigued by approximately 15% (p < 0.01); for left flexion, the left spenus capitis and left sternocleidomastoid fatigued by approximately 7.2% (p = 0.02) and approximately 11.2% (p = 0.03), respectively; in no trials did the trapezius muscles display fatigue as measured by EMG. The smaller agonist muscles were the most susceptible to fatigue during submaximal isometric endurance movements in the cervical muscles of helicopter aircrew.
ISSN:0026-4075
1930-613X
DOI:10.7205/milmed-d-00-7409