Laboratory Evaluation of Isometric Strength Associated with Typical Scaffold end Frame Disassembly Postures

Abstract

Overexertion injuries comprise the largest category of nonfatal injuries among construction groups which include scaffold erectors. These injuries typically occur when the biomechanical stresses associated with tasks such as lifting, carrying, pushing, etc. exceed the workers' strength capacity. This study was conducted to estimate the whole body isometric strength capability of construction workers in a typical symmetric lifting posture (baseline) and seven postures associated with scaffold end-frame disassembly. A computer controlled data acquisition system and custom fabricated test fixture complete with Bertec force platforms were used to quantify isometric strength in each of the postures. The whole-body isometric strength values (457 N mean) in the baseline posture for the subjects tested were higher than those of comparable industrial workers found in the literature (323 – 430 N mean). Threeof the scaffold disassembly postures resulted in considerable biomechanical stress to workers. The study group produced sufficient isometric forces in the remaining four postures which would reduce the risk of overexertion injuries due to disassembly of scaffold end-frames.