Effect of lifting belts on trunk muscle activation during a suddenly applied load

The National Institute for Occupational Safety and Health suggests there is insufficient biomechanical or epidemiological evidence to recommend the us e of back belts in industry. From a biomechanical perspective, previous wor k suggests that lifting belts stiffen the torso, particularly in the fronta l and transverse planes. To determine whether lifting belts stiffen the tor so and alter the trunk muscle response during a sudden loading event, we te sted the hypotheses that (a) lifting belts alter peak muscle activity recor ded with electromyography (EMC) during sudden loading and (b) lifting belts have a larger impact on trunk muscle response when sudden loads are applie d asymmetric to the torso's midsagittal plane. A sudden load was delivered to 10 men and 10 women without history of low back disorder via a cable att ached to a thoracic harness: motion was restricted to the lumbar spine. Res ults indicate that gender was not a significant Factor in this study. The l ifting belt reduced the peak normalized EMG of the erector spinae muscles o n average by 3% during asymmetric loading, though peak normalized EMG was i ncreased by 2% during symmetric loading. Lifting belts have been shown to s lightly reduce peak erector spinae activity during asymmetric sudden loadin g events in a constrained paradigm; however. the effects of lifting belts a re too small to provide effective protection of workers. Actual ol potentia l applications include the assessment of lifting belts as protective device s in workers based on the effects of lifting belts on the trunk muscle acti vity.