[A monitoring study of electromyography median frequency on fatigue of erector spinalis in drivers working at high altitude].
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.
Liang
Hongying
H
Orthopedic Institute of PLA, No. 304 Hospital, Beijing 100037, China.
Wu
Wenwen
W
Wang
Sheng
S
Yu
Hong
H
Hou
Shuxun
S
He
Lihua
L
Sun
Fei
F
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*