The effects of a back belt on posture, strength, and spinal compressive force during static lift exertions

Abstract

The experiment reported in this paper evaluated changes in lifting posture, static lifting strength and the estimated L3/L4 spinal compressive force resulting from the use of an abdominal support or `back' belt. Torso posture and maximum static lift strength were measured for eight male and eight female subjects using symmetric and asymmetric hand positions at calf height and elbow height. Body posture, and hand forces were also used as input to a three-dimensional static biomechanical model of the torso used to estimate L3/L4 spinal compressive force. The results showed axial twist of the torso to be significantly lower for calf height asymmetric exertions when the abdominal support belt was worn. The measured reduction in axial twist was approximately four degrees. No other significant effects on posture due to the support belt were found. Static lift strength was not significantly increased or reduced when the support belt was used. Predicted spinal compressive force was significantly lower when a support belt was worn (2840 N compared to 3125 N when the belt was not worn). Overall, the results of the experiment demonstrate a very limited benefit to the user of abdominal support belts, primarily due to reduced or restricted motion during asymmetric and lower-level lifts. Relevance to industry Back belts are commonly used in industry to mitigate manual materials handling hazards. One assumption often made by those recommending the use of back belts is that they substantially reduce the bending and twisting of the torso. The experiment reported in this paper tests this assumption and provides information on the utility of back belts.