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Description:
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The focus of this current study was to determine whether two recommended weight lifting (RWL ) conditions would result in the predicted 34kN compressive force at the L5 / Si disc for a variety of lifters . Since the revised NIOSH lifting equation was based on the assumptions of the various approaches—biomechanical , physiological , and psychophysical—in addition to the research findings of numerous experts in the field and feedback from the previous NIOSH equation , it was hypothesized that the mean of all of the peak compressive forces found at the L5 /Si disc resulting from the lifting of the recommended weight limits for two series of lifts would be equal to 3 -4kN . The alternate hypothesis was that the mean of all of the peak compressive forces found at the L5 /Si disc would not be equal to 3 -4kN . Secondly , there was an additional null hypothesis that the mean of all of the peak compressive forces at the L5 /Si disc for anytime in the lift , for either gender , or for either of the two lifting conditions -all examined both statically as well as dynamically in separate analyses—would equal 3 -4kN . Its alternative hypothesis would be that the mean of these peak compressive forces forces at the L5 /Si disc would not be equal to 3 4kN . Hence there was an underlying goal to not only look at the overall quantitative results , but to validate the effects for a variety of conditions as well as subjects . It was then possible to draw conclusions about the extent to which the equation was more protective of males than females , of persons doing certain lifts more than others , or at earlier than later times in a repetitive sequence . The ad hoc committee itself - -M . M . Ayoub , Donald B . Chaffin , Colin G . Drury , Arun Garg , and Suzanne Rodgers acknowledged the need for ongoing validation of the new lifting index's ability to reduce worker injury by accurately predicting hazardous manual materials tasks (Waters et al , 1993 ) . It is hoped that the current study can add to the "margin of safety" for the human back . |