Effects of vibration-based biofeedback on multifidus muscle activity and pelvic tilt angle in subjects with hip flexion limitation

Abstract

BACKGROUND: Sedentary work may lead to low back pain. In particular, a slumped sitting position may exacerbate low back pain because of tissue damage caused by excessive lumbar flexion and posterior pelvic tilting. Subjects with low back pain may have excessive changes in the lumbopelvic posture and back muscle activity in the sitting position. OBJECTIVE: The purpose of this study was to compare the effects of vibration-based biofeedback using a motion sensor belt and no biofeedback on multifidus (MF) muscle activity and pelvic tilt angle during typing. METHODS: Thirty subjects with low back pain accompanied by hip flexion limitation (15 each in the biofeedback and non-biofeedback groups) were enrolled. Electromyography was used to investigate MF muscle activity before and after typing for 30 min. Pelvic tilt was measured after typing in a sitting position for 30 min. Independent t-tests were used to compare MF muscle activity, and pelvic and second sacrum tilt angles, between the biofeedback and non-biofeedback groups. RESULTS: After typing for 30 min, changes in MF muscle activity (11.45% and -7.19% for the biofeedback and nonbiofeedback groups, respectively) and pelvic and second sacrum tilt angles (3.15∘ and 4.12∘ for the biofeedback group and -11.05∘ and -18.16∘ for the non-biofeedback group, respectively) were significantly smaller in the biofeedback than non-biofeedback group (p< 0.05). CONCLUSION: Vibration-based biofeedback minimizes the reduction in MF muscle activity and changes in pelvic and second sacrum tilt angles during typing in individuals with low back pain accompanied by hip flexion limitation.