Quantitative Evaluation of Lumbar Segmental Stability using a Pressure Biofeedback Unit

Abstract

This study examined the method for quantitative assessment of lumbar segmental stability (LSS) us ing a Pressure Biofeedback Unit (PBU). The subjects were 10 healthy men with no history of low back pain. The task movement consisted of placing the PBU under the lumbar region in the dorsal supine position and instructing the subject to raise and lower the right leg 10 times. This task movement was performed under two conditions:the transversus abdominis muscle (TrA) were not contracted (CON), and TrA were contracted (abdominal draw in maneuver: ADIM). As an index of LSS, the coefficient of variation (CV) of PBU pressure change during two tasks. Surface electromyography (EMG) was used to determine the level of muscle activity (%EMGmax) of the trans versus abdominis-obliquus internus (TrA-OI) muscles. The results that CV values of PBU were significantly lower in the ADIM than in the CON. Moreover, TrA-OI muscle activity was significantly higher in the ADIM, with a muscle activity level of around 30%EMGmax. Based on these results, the method used in this study could be used to quantify LSS. In addition, LSS did not require excessive contraction of the TrA, which could be achieved by main taining contraction at a relatively low effort level.