The effect of lumbar extension training with and without pelvic stabilization on lumbar strength and low back pain.

INTRODUCTION: A dynamometer employing a stabilization procedure (lumbar extension machine, MedX, Ocala, FL) is effective in improving strength and reducing symptoms of low back pain (LBP), and researchers have hypothesized that this effectiveness is due to the pelvic stabilization. However, effects of the dynamometer with and without pelvic stabilization on LBP have not been compared: This was the aim of the present study.

METHODS: Forty-two chronic LBP patients were randomly assigned to a lumbar extension training with pelvic stabilization group (STAB; n=15), a lumbar extension without pelvic stabilization group (NO-STAB; n=15) and a control group (n=12). STAB and NO-STAB participants completed one weekly session of dynamic variable resistance exercise (one set of 8-12 repetitions to fatigue) on the lumbar extension machine (with or without pelvic stabilization) for 12 weeks. Pre- and post-test measures of self-reported LBP (101-point visual analog scale; pre-test mean of 25), related disability (Oswestry disability index; pre-test mean of 34) and lumbar strength were taken.

RESULTS: After the exercise program, the STAB group increased significantly in lumbar strength at all joint angles, and decreased significantly in visual analogue and Oswestry scores. However, there were no significant changes in these variables in the NO-STAB and control groups.

DISCUSSION: Isolated lumbar extension exercise is very effective in reducing LBP in chronic patients. However, when the pelvis is not stabilized, otherwise identical exercises appear ineffective in reducing LBP.