Back Brace Belt
A Lower Back Pain Solution

Center for Ergonomic Research
Miami University

Postural Evaluation of a New Back Belt Design

Marvin Dainoff, Leonard Mark, Shawn Oates, and Dean Smith

Abstract

A newly designed back belt (Back A Line) is now available. The belt is not elastic, but provides a stiff form-fitted surface in the lumbar region of the spine. It is argued that this design will actually stimulate abdominal muscles by providing resistance.

The potential effectiveness of the new back belt was evaluated in a controlled laboratory test. This test is based on a well established set of procedures developed in our laboratory involving the investigation of postural changes during reaching.

The basic goal of these studies was the analysis and determination of postural transitions during reaching tasks. To take the simplest example, for me to reach an object placed relatively close to me (at a distance less than my arm length), I can just extend my arm. If the object is placed at a distance longer than my arm length, I will need to bend my trunk to reach it. Thus, depending on the distance of target, two different postural configurations are employed. One uses an arm-only reach; the second an arm-plus-trunk reach. However, a consistent finding from this set of studies in our laboratory is the transition point between configurations does not occur at the maximum distance set by the subject's anthropometry (e.g., arm length) but at an closer distance. This transition point can be manipulated by changes in both task and starting postures. We have argued that the particular location of the transition point may reflect a user-generated margin of safety; protecting against overloading at the extremes of ranges of motion.

Preliminary results indicate that when subjects wore the belt while reaching, they tended to have transition points closer to their bodies, than while not reaching. Hence, the belt seems to act to preserve a greater margin of safety--keeping the user from extreme ranges of motion. It is interesting, however, that this effect only seems to happen when the task requires a great deal of stability (picking up a small bead with a needle.) There was no difference in transition point when subjects were asked to perform a simpler task (picking up a block.) This difference in outcomes between tasks can, if verified, lead credence to the argument that the potential protective aspect of the belt is manifest when the task requires postural stability.