Similar to all activities requiring physical exertion. This mechanism seems to be supported by tests carried out by Myers et al. (2008) who found raised heart rates and oxygen usage during transits on board high speed marine craft. Various injuries and injury mechanisms are associated with WBV and repeated shock. With very few studies into the effects of repeated impacts associated with high speed marine craft motions, in spite of

the reported significant risk of injury, limited data is available to identify the injury mechanisms. This is further compounded by the ethical difficulties in reproducing the dangerous learn more motions in a laboratory. Indicative scales of vibration magnitudes and typical acceleration limiting criteria have been developed as shown in Table 6. However, measures based on individual motion magnitudes, ignoring vibration frequency, duration, direction, posture and transfer points, cannot adequately describe motion severity. Frequency weighting can improve their representation of motion severity, however PLX 4720 the results then become highly dependent on the manner in which the weightings are calculated (Griffin, 1990). Although

lower back pain, diagnosable as damage to vertebrae or intervertebral discs, is one of the most commonly reported effects of whole body vibration, no specific dose–effect relationship, relating injury to vibration exposure has been identified (Stayner, 2001). Although Bovenzi and Betta (1994) report that there is a linear relationship between posture and the prevalence of lower back pain. Typically lower back pain is associated with vibration magnitudes between 1.0 m/s2 and 10 m/s2, rather than exposure durations (Griffin, 1990, Stayner, 2001 and Myers et al., 2008) and posture is considered a compounding ADP ribosylation factor factor in almost all epidemiological studies (Stayner, 2001). Posture has also been suggested to decrease the spine’s ability to resist

loads by a factor of up to 100 (Seidel et al., 1998) and that sitting can place additional stress on the musculature and intervertebral discs of the lumbar spine (Stayner, 2001). Mathematical modelling, replicating the mechanisms of vibration within the human body have been attempted by Pankoke et al. (1998) amongst others. However, conclusive results are difficult to obtain due to the invasive nature of any attempt to validate the results. Performance and safety concerns regarding high speed marine craft motion exposures are widespread and with the increasing legislation, including the EU directive (European Union, 2002) and operators cost concerns, including the possibilities of insurance pay-out, sick pay and operational failure, there is a need to either isolate the occupants from the motion exposure or reduce the motion exposure.