title: [A monitoring study of electromyography median frequency on fatigue of erector spinalis in drivers working at high altitude].
abstract: OBJECTIVE
  To evaluate the role of muscle fatigue in the pathogenesis of high prevalence of low back pain(LBP) in drivers who work at high altitude, in order to seek the effective measures for prevention and treatment of LBP.
  
  
  METHODS
  The spectral electromyographic(EMG) changes during isometric contraction of erector spinalis to fatigue in 26 drivers in the field were consecutively recorded after daily driving for 5 days. The relationship between the decline of median frequency and the development of the back extensor fatigue were analyzed.
  
  
  RESULTS
  The decline rates of EMG median frequency of the erector spinalis on 1-5 working day [(-0.258 +/- 0.087), (-0.248 +/- 0.070), (-0.256 +/- 0.097), (-0.267 +/- 0.093), (-0.274 +/- 0.081)%/s respectively] were significantly different from that of baseline measured before work [(-0.175 +/- 0.114)%/s, P < 0.05 or P < 0.01]. A positive correlation was also found between the decline rate and the working time(r = -0.809, P < 0.05).
  
  
  CONCLUSIONS
  The high prevalence of LBP in the drivers working at high altitude is due to acumulative fatigue of back extensor resulting from long-distance driving, lack of proper rest, decrease of muscle endurance and increase of liability to fatigue, consequently leading to the muscle dysfunction and finally LBP.
authors.affiliation: Orthopedic Institute of PLA, No. 304 Hospital, Beijing 100037, China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Liang
authors.forename: Wenwen
authors.initials: W
authors.lastname: Wu
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.forename: Shuxun
authors.initials: S
authors.lastname: Hou
authors.forename: Lihua
authors.initials: L
authors.lastname: He
authors.forename: Fei
authors.initials: F
authors.lastname: Sun
mesh_terms: D000531:Altitude; D001334:Automobile Driving; D004576:Electromyography; D006801:Humans; D017116:Low Back Pain / Q000209:etiology* / Q000503:physiopathology; D018763:Muscle Fatigue / Q000502:physiology*; D009784:Occupational Diseases / Q000209:etiology*