Whole body vibration and posture as risk factors for low back pain among forklift truck drivers

A cross-sectional study was conducted to investigate the risks from whole-body vibration and posture demands for low back pain (LBP) among forklift truck (forklift) drivers. Using a validated questionnaire, information about health history was obtained over a period of two weeks in face-to-face interviews. The forklift drivers were observed in respect of their sitting posture, including frequency with which different positions were adopted (bending, leaning and twisting) and postural analyses were conducted using the OWAS and RULA techniques. Forklift vibrations at the seat (exposure) were measured in the three orthogonal axes (x-fore and aft, y-lateral and z-vertical) under actual working conditions according to the recommendations of ISO 2631-1. The results showed that LBP was more prevalent amongst forklift drivers than among non-drivers and driving postures in which the trunk is considerably twisted or bent forward associated with greatest risk. Furthermore, forklift drivers showed to be exposed to acceptable levels of vibration in the x- and y-directions (i.e., below the EU Physical Agents Directive on Vibration Exposure recommended action level-0.5 m/s2), but not in the z-direction. There were indications that whole-body vibration acts associatively with other factors (not independently) to precipitate LBP.