Revisited: Comparison of two techniques to establish maximum acceptable forces of dynamic pushing for male industrial workers

Abstract

The purpose of this experiment was to replicate a previous psychophysical experiment [Ciriello, V.M., McGorry, R.W., Martin, S.E., Bezverkny, I.B., 1999b. Maximum acceptable forces of dynamic pushing: comparison of two techniques. Ergonomics 42, 32–39] which investigated maximum acceptable initial and sustained forces while performing a 7.6 m pushing task at a frequency of 1 min −1 on a magnetic particle brake treadmill versus pushing on a high-inertia pushcart. Fourteen male industrial workers performed both a 40-min treadmill pushing task and a 2-h pushcart task, with a unique water loading system, in the context of a larger experiment. During pushing, the subjects were asked to select a workload they could sustain for 8 h without “straining themselves or without becoming unusually tired, weakened, overheated or out of breath.” The results revealed that similar to the previous study maximum acceptable sustained forces of pushing determined on the high inertia cart were significantly higher (21%) than the forces determined from the magnetic particle brake treadmill. These results were countered by an 18% decrease in maximum acceptable forces for the criterion magnetic particle brake treadmill task, perhaps due to secular changes in the industrial population. Based on the present findings, it is concluded that the existing pushing data [Snook, S.H., Ciriello, V.M., 1991. The design of manual tasks: revised tables of maximum acceptable weights and forces. Ergonomics 34, 1197–1213] still provides an accurate estimate of maximal acceptable forces for this pushing distance and frequency. Relevance to industry Jobs are often redesigned to eliminate lifting and to include carts for transporting loads. Our database on maximum acceptable forces of pushing on a magnetic particle braked treadmill has been used as a tool to design manual handling tasks. This article links the existing database with actual cart pushing.