title: Measuring neuromuscular fatigue in cervical spinal musculature of military helicopter aircrew.
abstract: 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.
  
  
  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 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.
  
  
  CONCLUSIONS
  The smaller agonist muscles were the most susceptible to fatigue during submaximal isometric endurance movements in the cervical muscles of helicopter aircrew.
authors: Faculty of Kinesiology and Health Studies, 3737 Wascana Pkwy, University of Regina, Regina, SK, Canada S4S 0A2.
authors: Michael F
authors: MF
authors: Harrison
authors: J Patrick
authors: JP
authors: Neary
authors: Wayne J
authors: WJ
authors: Albert
authors: Usha
authors: U
authors: Kuruganti
authors: James C
authors: JC
authors: Croll
authors: V Carol
authors: VC
authors: Chancey
authors: Bradley A
authors: BA
authors: Bumgardner
mesh_terms: D000328:Adult; D000401:Aircraft; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008889:Military Personnel; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D009334:Neck Muscles / Q000503:physiopathology*; D019547:Neck Pain / Q000503:physiopathology*; D009784:Occupational Diseases / Q000503:physiopathology*