Postural Stability during Simulated Drywall Lifting and Hanging Tasks

Drywall lifting and hanging tasks require workers to handle heavy and bulky drywall sheets and maintain awkward postures to install materials onto the wall or ceiling. Previous studies indicated that drywall lifting and hanging tasks cause more fall-related injuries than any other tasks. Activities associated with these two tasks often result in muscle fatigue and propensity for loss of balance. The objective of this study is to identify the methods resulting in the least postural instability during drywall lifting or hanging drywall tasks. Sixty construction workers with at least 6 months of drywall-installation experience participated in this study. Each subject performed four lifts of a drywall sheet using one of the four lifting methods. The subject was also asked to perform 4 hanging trials using one of the four hanging methods. This study is a completely randomized repeated design with lifting and hanging methods randomly assigned to each subject. Workers' postural instability was quantified using a piezoelectric-type force platform. Two postural sway variables (sway length and sway area) and three instability indices (IPSB, SAR, WRTI) were used to describe workers' propensity for loss of balance associated with drywall lifting and hanging. Analyses of variance showed that the effects of different lifting and hanging methods were significant on the two postural-sway variables and the three postural instability indices. Results from this study suggest that the horizontal lift of a drywall sheet with both hands positioned on the top of the drywall appeared to cause least postural sway and instability. Furthermore, hanging drywall onto the ceiling horizontally produced less postural sway and instability than vertically.