Back and neck extensor loading and back pain provocation in urban bus drivers with and without low back pain

This study assessed low back and trapezius muscle activity in bus drivers, with or without recurrent low back pain (LBP), during the long term driving. In addition, low back and neck-shoulder pain intensities and fatigue were measured and the effect of low back support was observed. Also the possible source of LBP was attempted to assess by vibration pain provocation test and lumbar MRI. Forty bus drivers (recurrent LBP n = 25) participated in this study. Low back and neck-shoulder pain and subjective fatigue intensity was assessed by visual analogue scales (VAS) before and after driving. Lumbar paraspinal and trapezius muscle activation during driving was measured by surface EMG. Vibration pain provocation test was applied for all subjects. Average paraspinal myoelectric activity during driving was approximately 1% of MVC in both groups. Average trapezius myoelectric activity during driving was from 2 to 4% of MVC. Trapezius muscle activity was higher in back healthy drivers than in those with LBP. The low back support had no effect either on paraspinal or trapezius EMG activity. Low back and neck-shoulder fatigue increased during driving in both groups especially in those subjects with positive vibration pain provocation. The neck-shoulder pain and fatigue were more severe in drivers suffering from LBP. Low back support had no effect on low back and neck-shoulder subjective fatigue and neck-shoulder pain but tended to limit the LBP increase during driving. Paraspinal muscle loading in urban bus drivers was very limited and either LBP or ergonomic low back support had no effect on it. Trapezius muscle seemed to be less active in drivers suffering from recurrent LBP. Internal disc disruptions may expose to pain and fatigability during driving.