THE EFFECT OF BACK BELT USE ON ISOMETRIC LIFTING FORCE AND FATIGUE OFTHE LUMBAR PARASPINAL MUSCLES

Study design. A repeated measures multivariate design to assess the ef fect of back belts on isometric lifting force and lumbar paraspinal mu scle fatigue. Objective. To determine the efficacy of lumbar back belt s in minimizing a loss in isometric force production and fatigue of lu mbar paraspinal muscles. Summary of Background Data. Increased prevale nce of back belts in industry and lack of scientific evidence supporti ng them suggested additional research was needed. There has been no co nclusive research to substantiate manufacturer claims that use of belt s reduces fatigue of lumbar paraspinals. Methods. Twenty-four subjects , 13 men and 11 women, were tested twice: once with and once without a belt. All subjects performed a dynamic lifting task at a rate of 10 l ifts per minute for 20 minutes. Surface electromyograms from the lumba r paraspinals and isometric force measurements were recorded during a static maximal isometric lift at 0, 10, and 20 minutes. Load during th e dynamic task was determined as 20% of initial maximum isometric forc e. Electromyographic data were used to detect changes in median power spectral frequencies. Muscular fatigue was indicated by a reduction in median power spectral frequency values or a decrease in isometric for ce-generating capacity. Results. Multivariate and univariate analyses suggest that there is no effect on lumbar paraspinal muscle fatigue or isometric lifting force production as a result of back belt use. Conc lusions. These findings do not support the use of back belts for the p urpose of minimizing either lumbar paraspinal muscle fatigue or a loss in isometric lifting force production.