Fractional Factorial Analysis of Lifting and Carrying Tasks to Determine the Effect of Different Parameters and their Interactions

Abstract

The National Institute for Occupational Safety and Health (NIOSH) developed a lifting equation in 1981 to indicate ‘‘safe’’ occupational lifting limits. This equation was revised in 1991. The equation uses a series of lifting multipliers (parameters) to calculate corresponding recommended task weight limits. Due to the nature of risk factor interactions, the limits obtained from the NIOSH equation may not be appropriate for all lifting tasks. This laboratory experiment will examine the effect of lifting parameters and their interactions as follows: lifting frequency; vertical lifting distance; and load weight. In this simulation study, four different subjects were taken to lift the weights in different combinations of lifting parameters, in which different lifting frequencies, with different load weights and different vertical lifting heights (knee, waist, shoulder, and maximum reach) will be considered. The subjects will do symmetric lifting for a period in sagittal plane adopting free-style lifting technique. The recorded working heart rates will be normalized based on the maximum heart rate obtained during maximum aerobic power measurement. Then, stepwise linear regression analysis will be performed to identify the best predictive model using important parameters.