Floor slope effects on lifting kinematics and kinetics

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DESCRIPTION (provided by applicant): This is a revision of a previously submitted R03 proposal. The long-term objective of this research program is to develop guidelines for the Manual Materials Handling task of lifting an object from an inclined floor surface in order to reduce the risk of low-back pain and injury at the workplace. Specific aims include determining lifting capacities while facing up an incline, down an incline, and compare them to lifting the same object from a level floor surface. Additional efforts will be made to quantify the kinematics of lifting as well as the loading on the low back in order to understand how the different lifting conditions affect the lifter, and if one lifting condition places a person at an increased risk of injury compared to other conditions, Efforts will also be made to examine how different lifting techniques (altered foot placement) may reduce the likelihood of low-back pain or injury caused from lifting on an inclined surface. Two separate experimental protocols will be utilized in order to realize the long-term objectives of this two-year research program. The first protocol will determine lifting capacities under three distinctly different lifting situations with the feet placed in the same position relative to the lifted object: facing up an incline, facing down an incline, and on a level surface. The psychophysical method will be used to determine lifting capacities in each condition. This method has been used successfully in the past to determine lifting capacity guidelines for other situations. Also, as part of this protocol, kinematics of motion, the loading on the lower back, and muscle activity of key muscles in the back will be assessed in each condition. Sagittal plane cinematography will be combined with anthropometrics parameters to perform an inverse-dynamics analysis of the lifts. The second protocol will be conducted in the same manner as the first. However, foot placement will be staggered (one foot forward of the other) in the two inclined lifting situations while foot placement will be even in the level surface condition. Participant numbers will allow statistical comparisons of males, females, and the whole group. The results from these two protocols will be combined with the intent to produce guidelines related to lifting on inclined surfaces.