On The Validity of an Isometric Biomechanical Model of Worker Strengths

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Abstract
Over the last 18 years the Center for Ergonomics at The University of Michigan has worked to develop a computerized, biomechanically based model to predict worker muscle strengths in various tasks. During the last few years new input strength data has been acquired from published works of others. Worker isometric strength testing also has been performed by the Center in various industries to determine gross lifting, pushing and pulling capabilities of a heterogeneous group of men and women. These data, acquired from 1577 men and women are compared to the strength predictions of the biomechanically based model. For prediction of mean strength capabilities of both men and women performing varied types of symmetric sagittal plane exertions, the model results were relatively unbiased and were well correlated with r 2 between 0.85 and 0.88 with the population data. The results were not as good for predicting the mean strengths of two-handed assymetric exertions (r 2 between 0.54 and 0.74), and for one-handed, sagittal plane exertions (r 2 = 0.50). The utility and limitations of such a modelling approach to human strength prediction are discussed.