Abstract
Many professional truck drivers experience low back pain (LBP) which is believed to be associated with exposure to whole body vibration (WBV). As a part of a randomized controlled trial, this study measured WBV exposures from 98 professional truck drivers continuously during their regular work shift (8-12 hours). The daily weighted average A(8), vibration dose value VDV(8), and vector sum A(8) and VDV(8) exposures were evaluated for important determinants of WBV exposures including the roads travelled on, year of truck manufacture, truck manufacturer, and seat manufacturer. LBP was also measured using a standardized visual analog scale. The results demonstrated that there were substantial differences in health risk prediction between the predominant axis exposure (advocated by the European Union Vibration Directives) and vector sum exposures. Moreover, VDV(8) measures were above the International Organization for Standardization and European Union daily exposure action limit (9.1 m/s2). The average LBP score on a 0 to 10 point scale was 2.7 (SD: 2.0) ranging from 0 to 8. When comparing the two major manufacturers of truck seats, one truck seat had higher vertical, z-axis A(8) exposures than the other (24%, p =0.01); and this WBV exposure difference appeared to be reflected by the LBP outcomes. These results indicate that there are performance differences between seats in the attenuation of WBV exposures and truck drivers’ impulsive WBV exposure can exceed recommended daily action limits.