An expert cognitive approach to evaluate physical effort and injury risk in manual lifting—A brief report of a pilot study

Abstract

AbstractAlthough the development of the National Institute for Occupational Safety and Health (NIOSH) equation was partly based on the expertise of committee members convened under the auspices of NIOSH, to our knowledge, there is no study reported in the published literature that examined the role of professional expertise in determining the relative contribution of different lifting task variables to effort exertion. In this study, we explored whether professional expertise can be relied on, through the use of a systematic procedure, to quantify the effects of lifting task parameters on perceived effort and risk of injury outcome measures.Three international experts participated in the research reported herein and evaluated the interactive effects of 6 lifting variables: (a) weight of load, (b) horizontal distance, (c) frequency of handling, (d) work duration, (e) twisting angle, and (f) height of lift. They predicted the lifting effort and the injury risk of a large number of lifting configurations. A linguistic approach was used to describe the lifting activities. Logistic regression analyses were employed to model effort as a function of various lifting task variables.The results showed that all 3 experts rated the weight of load as the most dominant variable and the height of lift as the least important variable. Furthermore, they differed slightly in ranking the relative importance of other variables. In general, the effect of weight of load on physical effort was, at a minimum, 2 times more important than other lifting task variables. The horizontal distance, work duration, frequency, and twisting angle variables were considered to be more important than the height of lift by 25% to 33%. Collectively, these findings indicate that the experts agreed on the most and least important variables. In between, the relative importance of other variables was dependent on the professional training of the expert.The results further demonstrated that an increase in perceived physical effort was associated with an increase in the perceived risk of injury in the moderate‐ to high‐range values. There was a large variance, however, at the lower levels of physical effort and perceived risk. Collectively, the aforementioned findings confirm the notion that low‐level effort exertion activities are not perceived by the experts as risky. As the level of exertion increases to moderate values, however, the experts start to be conscious about the risks involved in the manual lifting activities. Therefore, one should not treat these 2 variables as equal, because they may reflect 2 separate dimensions in the low range. In the moderate to high range, they have some common variance but they may still reflect some differences to a certain extent. © 2002 Wiley Periodicals, Inc.