Perceived postural instability during simulated lifting tasks in construction workers

Abstract

There are various occupational fatal/nonfatal injuries in construction industry, in which falls or fall-related injuries have been identified as a leading cause. The instability of working postures can lead to falls in construction workers. This research investigated the effects of lifting posture (6 levels), lifting load (2 levels: 0KG, 10KG) and standing surface slope (2 levels: 0°, 18°) on postural instability (PI) based on subjective perceptions (0-10 rating scale). Thirty young subjects participated in this study and performed six simulated lifting postures under four different experimental conditions (2 lifting loads × 2 standing surface slopes). Results showed statistically significant main effects (p<0.0005) of each factor on PI. Both sloped standing surface and lifting load could increase PI (except full squatting), however, lifting load had a larger effect on PI than sloped standing surface. There were also significant interactions between lifting posture and lifting load in the conditions of both flat (p=0.000) and sloped (p=0.000) standing surfaces, between standing surface and lifting postures only under no load condition (p=0.000), between standing surface and lifting load only for full squatting posture (p=0.000). Among 6 lifting postures, full squatting was very different that it’s more stable with lifting load than no load in flat standing surface condition, and more stable in the sloped standing surface condition than in the flat when no lifting load. The reliability of subjective perceptions on PI, as assessed by Intraclass Correlation Coefficient-ICC (3, 1), was excellent in 10KG load conditions (0°: ICC=0.919; 18°: ICC=0.940), and good (0°, ICC=0.890) to moderate (18°, ICC=0.673) in no load (0KG) conditions. The results demonstrated that participants could consistently rate their perceptions of PI, especially when the PI level was high. The three factors had not only significant main effects on PI, but also significant and complicated second-order interaction effects. These findings implicated that all above three factors should be taken into account at the same time to prevent falls in construction workers.