Measuring Neuromuscular Fatigue in Cervical Spinal Musculature of Military Helicopter Aircrew
Source: Military Medicine, Volume 174, Number 11, November 2009 , pp. 1183-1189(7)
Abstract:ABSTRACTNeck 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. Methods: 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. Results: For extension, the left and right splenius capitis fatigued by ~21-22% ( p < 0.01); for flexion, the left and right sternocleidomastoid fatigued by ~11-14% ( p < 0.01); for right flexion, the right sternocleidomastoid fatigued by ~15% ( p < 0.01); for left flexion, the left spenus capitis and left sternocleidomastoid fatigued by ~7.2% (p = 0.02) and ~11.2% ( p = 0.03), respectively; in no trials did the trapezius muscles display fatigue as measured by EMG. Conclusion: The smaller agonist muscles were the most susceptible to fatigue during submaximal isometric endurance movements in the cervical muscles of helicopter aircrew.
Document Type: Research article
Affiliations: 1: Faculty of Kinesiology and Health Studies, 3737 Wascana Pkwy, University of Regina, Regina, SK Canada S4S 0A2. 2: Faculty of Kinesiology, Lady Beaverbrook Gym, 2 Peter Kelly Drive, University of New Brunswick, Fredericton, NB Canada E3B 5A3. 3: United States Army Aeromedical Research Laboratory, Building 6901, Fort Rucker, AL 36362-0577.
Publication date: 2009-11-01
- Military Medicine is the Association's official monthly journal. The objective of the Journal is to promote awareness of Federal medicine by providing a forum for responsible discussion of common ideas and problems relevant to Federal healthcare. Its mission is: To increase healthcare education by providing scientific and other information to its readers; to facilitate communication; and to offer a prestige publication for members' writings.
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