The Effect of Variations in Trunk Models in Predicting Muscle Strength and Spinal Loading

Abstract

A unified modeling technique is proposed to predict the strength contour of trunk muscles during isometric exertions, which can identify the feasibility of task performance and quantify the utilization ratio for assessment of risk of development of muscular fatigue and over-exertion injury. In addition, the proposed model can estimate the joint reaction forces during performance of the feasible complex loading task in upright standing. Six anatomical models and six cost functions suggested by various research groups were considered in determining their effects on the predicted three-dimensional strength and lumbar intervertebral joint reaction forces obtained using linear and nonlinear optimizations. The present investigation has shown the importance of the fidelity of anatomical models used in estimation of spinal loading and trunk strength. The effect of cost functions on estimated compression and anterior-posterior shear forces was statistically significant. These models can assist in identifying the injurious tasks that must be ergonomically modified to prevent the risk of occupationally related low back injuries.