Reliability of Lift Alert(™) as a feedback device for detecting changes in body position.

The Lift Alert (™) is a small battery-operated unit, usually worn on the back of a worker's collar that is designed to provide a form of biofeedback about changes in trunk position during lifting tasks. The purpose of this study was to determine how consistent the Lift Alert (™) was at each of five different sensitivity settings (A-E) in detecting changes in trunk flexion in a given individual during a controlled bending maneuver. The subjects were videotaped while performing a series of trials of bending maneuvers at each of the sensitivity settings according to a specific protocol. The videotapes were then converted onto a computer program where the still images were captured and marked for data analysis. The reliability of the Lift Alert (™) was determined by calculating a coefficient of agreement, that is, the percentage of trials that were within both 10 and 15 degrees for each of the trials at a given setting for a single individual. The coefficient of agreement for all trials at all five settings was 0.76 within 10 degrees and 0.92 within 15 degrees. The results of this study suggest that the Lift Alert (™) is a reliable device for detecting changes in trunk flexion during a controlled bending maneuver for a given individual.