Drivers of mobile machinery are exposed to vibrations and unfavourable postures that can lead to low back disorders. Measurements of the dynamic response (apparent mass and head-seat transmissibility) of the body exposed to vibration in the fore-aft, lateral and vertical directions were carried out for positions relevant to the usual driving positions. Deviations of the head and thorax in the sagittal plane have important effects: when vibrating in the fore-aft and vertical directions, the resonance frequency of the body is increased, and in the vertical direction, the transmission of vibrations to the head is also increased. Deviations of the head and thorax in the frontal or horizontal plane have small or insignificant effects.
