Symmetric and Asymmetric Stoop-Lifting Strength

Abstract

The strength capability of workers is an essential design criterion. Though true job simulated strength is most appropriate, availability of strength values in many standardized postures will permit selection of most suitable or a series of suitable strength values. Six normal young male subjects performed a maximal lifting effort in a stooping posture in isometric (with hip angles 60° and 90° flexion) and isokinetic modes (50 cm per second linear velocity). The isokinetic lift was performed from floor to knuckle height. Each lift was performed at half, three-quarters, and full reaches by each subject in sagittal, 30° lateral and 60° lateral planes. The strength was measured using the Dynamic Strength Tester (DST) described by Kumar et al (1988). The strength was inversely related to reach distance (p<0.0001). The largest declines in strength were between half and three-quarters reach distances (45% to 50%). From three-quarters reach to full reach, the drop was between 10% to 30%. With increasing asymmetry, the strength declined significantly (p<0.0001). The extent of this decline decreased at longer reaches. Based on these findings, a case is built for a biomechanical standardization of strength measurements.