The effects of pressure biofeedback on hip and trunk muscle activity and lumbopelvic alignment during one-leg standing

Abstract

BACKGROUND: During one-leg standing (OLS), optimum activity of the gluteus medius (Gmed), multifidus (MF), and quadratus lumborum (QL) muscles relies upon maintaining neutral lumbopelvic alignment. However, no studies have examined how using pressure biofeedback during OLS affects the activity of these muscles and the concomitant alignment of the pelvis and trunk. OBJECTIVES: The purpose of this study was to investigate the effect of pressure biofeedback on the activity of the Gmed, MF, and QL and the femoropelvic and trunk lean angles during OLS. METHODS: Twenty-four healthy males performed OLS with (PB+) and without (PB-) pressure biofeedback. For all OLS conditions, a pressure sensor was placed between the lateral surface of the humerus on the non-supporting side and the wall. Under the PB- condition, participants performed preferred OLS while the examiner measured the maximum pressure caused by trunk lean. Under the PB+ condition, participants were asked to perform at a threshold of 50% of the maximal pressure (PB+ 1 condition) and with minimal change in pressure (PB+ 2 condition). Muscle activities of MF, QL, and Gmed as well as the femoropelvic and trunk lean angles were measured under various OLS conditions. RESULTS: The activity of the Gmed, MF, and QL was greater under both PB+ conditions than under the PB- condition (p< 0.05). Also, both PB+ conditions resulted in a greater femoropelvic angle and reduced trunk lean angle. There were no significant differences in muscle activity, femoropelvic angle, or trunk lean angle between PB+ 1 and PB+ 2 (p> 0.05). CONCLUSIONS: These results suggest that pressure biofeedback is a useful modality for increasing the activity of the Gmed and trunk muscles, especially the MF muscle on the non-supporting leg side, and for preventing compensatory movements such as trunk deviation and pelvic lateral deviation during OLS.