Physiological effects of abdominal belt use during a lifting task

Abdominal belts are widely used for manual material handling (MMH) tasks in industry despite the lack of any definitive research findings confirming their efficacy. The NIOSH back belt working group, in its review of research conducted on back belt usage, concluded that ''the use of back bells may produce temporary strain on the cardiovascular system''. The working group's conclusion is apparently based on the results of a single study which identified significant increases in heart rate during aerobic exercise, and in systolic blood pressure during both aerobic and isometric exercises, when the tasks were performed while wearing a weight-lifting belt. Many researchers have studied the effects of the weight training/lifting belt, which is usually a rigid belt as opposed to the industrial abdominal belt which is flexible and may or may not have a rigid support in the lumbar region. Few research studies have investigated the physiological effects of abdominal belts as measured by heart rate and blood pressure. The current study investigated the physiological effects of a flexible abdominal belt in a MMH task. The task involved lifting and lowering a box from knuckle height to shoulder height for five 4-minute periods interspersed by rest periods determined by the subject's heart rate (HR). The weight lifted was 35% of the subject's maximum. The use of the belt did not affect systolic blood pressure. However, for subject's with lower absolute loads, an increase in heart rate was observed while wearing the belt, and, for subjects with higher loads, heart rate changes due to the task itself masked those caused by the belt. In conclusion, the theorized augmentative effect of the belt was not offset by an increased physiological cost at higher loads. These observations may lead one to hypothesize the existence of a critical weight (possibly within NIOSH limits) above which there is no physiological cost associated with wearing an abdominal belt.