Kappa Delta Award. Low back pain and whole body vibration.

The investigators describe their multifaceted approach to the study of the relationship between whole body vibration and low back pain. The epidemiologic study was a two center study of drivers and sedentary workers in the United States and Sweden. The vibration exposure was measured in the vehicles. It was found that the career vibration exposure was related to low back, neck, and shoulder pain. However, disability was related to job satisfaction. In vivo experiments, using percutaneous pin mounted accelerometers have shown that the natural frequency is at 4.5 Hz. The frequency response is affected by posture, seating, and seat back inclination. The response appears to be determined largely by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration, should be reduced for those recovering from these problems. Vibration attenuating seats and correct ergonomic layout of the cabs may reduce the risks of recurrence.