Abstract
The objective of this project was to study the effects of asymmetric (twisting) free dynamic lifting on back motion characteristics in the sagittal, frontal and transverse planes of the body. Back motion charateristics were quantified both as a function of task asymmetry and task weight. An experiment with 21 subjects was performed in the laboratory, which simulated free dynamic manual material handling tasks of the industrial workplace. The results quantified the range of motion, peak velocity, average velocity, and peak acceleration in each plane necessary to complete the task. Plots were made of the statistically significant back motion parameters. The results quantified the amount of transverse plane back motion required for specific task asymmetries. Task asymmetries greater than 120 degrees require transverse motion that puts a person at high risk of suffering a low back injury. The results provide new insight into factors associated with the risk of developing low back disorders.
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