Affiliations: Department of Industrial Engineering, North Carolina State University, Raleigh, NC, USA
Correspondence:
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Corresponding author: Gary A. Mirka, Department of Industrial Engineering, Box 7906, North Carolina State University, Raleigh, NC 27695, USA. E-mail: [email protected].
Abstract: The purpose of this research was to determine the impact of coupling and load magnitude on trunk dynamics during lifting activities. Subjects lifted a box that simulated three levels of coupling: good, fair and poor and seven levels of mass: ranging from 4.5-31.5 kg. The dependent variables were the peak dynamic moment generated about the lumbosacral joint and the peak vertical ground reaction forces produced during the lift. The results show that at low levels of box mass there are no significant differences in trunk dynamics and resulting peak dynamic moment across the different coupling conditions. However, when loads greater than 13.5 kg were lifted, a change in the normal dynamics of the lifting motion was noted, but only in the poor coupling condition, indicating an interaction between load and coupling. The results of this study indicate that the role of coupling under dynamic lifting conditions has both a perceptual and biomechanical basis that need to be considered when designing manual materials handling tasks.
