Does wearing a non-expanding weight lifting belt change psychophysically determined maximum acceptable weights and forces

Abstract

The most frequent and expensive cause category of compensable loss is the manual material handling (MMH). Ergonomic redesign of high-risk MMH tasks is the most effective way to minimize these loses. As an alternative to task redesign, back belts have been promoted by management and used by employees to help alleviate the physical demands of, otherwise, unacceptable tasks, despite a lack of the conclusive evidence that back belts will protect against low-back pain or low-back disability. Also, there is a concern that back belts may give the worker a false sense of confidence and encourage them to explore higher work levels. The purpose of this experiment was to investigate the effects of a back belt with maximum resistance to the circumferential expansion on psychophysically determined maximum acceptable weights (MAWs) and forces (MAFs) for a variety of lifting, lowering, pushing, pulling, and carrying tasks. Ten female and eight male industrial workers performed nine MMH tasks with and without a back belt within a larger study of 56 different tasks, which required 17 four-hour days to complete. A psychophysical methodology was used whereby the subjects were asked to select a workload they could sustain for eight hours without “straining themselves or without becoming unusually tired, weakened, overheated or out of breath.” The results revealed that the MAWs and MAFs of all tasks performed by women and all but one MAF of one task performed by men were not significantly affected by the back belt use. Based on these results, the use of a back belt did not change the perception of the subject's physical demands of the task since they chose similar psychophysically acceptable loads. Back belts are still commonly used in the industry despite lack of evidence that they will provide a decrease in low-back disability. This study illustrated that a worker's perception of the task was not altered by the back belt use, thus a worker's preference for the back belt use when job redesign has been limited or ignored should not be discouraged.