An Evaluation of the NIOSH Lifting Equation: A Psychophysical and Biomechanical Investigation
Using the results of psychophysical and biomechanical experiments, NIOSH (National Institute for Occupational Safety and Health) Recommended Weight Limit (RWL), the Lifting Index (LI), the form of the asymmetry multiplier, and the criterion for compression force were investigated. Analysis of the results indicated a significant difference between the NIOSH RWL and the reported Maximum Acceptable Weight of Lift (MAWL). Contrary to the NIOSH lifting equation, the form of the asymmetry multiplier was found to be non-linear. The overall average of peak compression force on the L5/S1 was 3685 N. Fifty-eight percent of all compression forces reported in the biomechanical experiment were found to exceed the suggested 3400 N set by NIOSH guidelines. These results support previous research findings on the validity of NIOSH guidelines.
A Review of Manual Load Lifting Models
The paper reviewed the three main approaches for setting limits of load to be limited manually. In the analysis the strengths and the weaknesses were highlighted and a need for a new approach using spinal shrinkage and some anthropometric dimensions was advocated. The approach may probably lead to the development of a safe weight of lift that may be subject-specific. It is expected that such an approach may be more protective of workers that the approaches presently reported in the literature.
Fuzzy modelling of relations between physical weight and perceived heaviness: the effect of size-weight illusion in industrial lifting tasks
Abstract In four experiments with 224 subjects the relationships between physical weight, subjective heaviness, and size of load (container) were investigated. The results were described with the help of fuzzy sets and processed further in a way, that the so called size-weight illusion—known from basic psychophysical research— could be determined for ranges of load relevant for industrial lifting tasks. From a quantitative analysis of the size-weight illusion by fuzzy sets we derived, that estimations of tolerable weights are influenced considerably by this effect. Some contradictory results from literature referring to lifting tasks with loads of different forms/sizes could be explained by antinome effects of the size-weight illusion and biomechanics.