Anthropometry-Corrected Exposure Modeling as a Method to Improve Trunk Posture Assessment with a Single Inclinometer

Abstract

Measuring trunk posture in the workplace commonly involves subjective observation or self-report methods or the use of costly and time-consuming motion analysis systems (current gold standard). This work compared trunk inclination measurements using a simple data-logging inclinometer with trunk flexion measurements using a motion analysis system, and evaluated adding measures of subject anthropometry to exposure prediction models to improve the agreement between the two methods. Simulated lifting tasks (n = 36) were performed by eight participants, and trunk postures were simultaneously measured with each method. There were significant differences between the two methods, with the inclinometer initially explaining 47% of the variance in the motion analysis measurements. However, adding one key anthropometric parameter (lower arm length) to the inclinometer-based trunk flexion prediction model reduced the differences between the two systems and accounted for 79% of the motion analysis method's variance. Although caution must be applied when generalizing lower-arm length as a correction factor, the overall strategy of anthropometric modeling is a novel contribution. In this lifting-based study, by accounting for subject anthropometry, a single, simple data-logging inclinometer shows promise for trunk posture measurement and may have utility in larger-scale field studies where similar types of tasks are performed.

Keywords:

• epidemiology
• ergonomics
• exposure assessment

ACKNOWLEDGMENTS

Laboratory support was provided by the Callaghan Spine Lab at the University of Waterloo under the supervision of Dr. Jack P. Callaghan with the assistance of Tyson Beach, Erika Nelson-Wong, and Robert Parkinson. LABVIEW programming and technical assistance was supported by Dr. Peter W. Johnson at the University of Washington. This work was funded by the WorkSafeBC, the Michael Smith Foundation for Health Research, and the Washington State Medical Aid and Accident Fund.