Influence of force-time parameters of hip abductors on maintaining balance in frontal plane in young healthy females

Purpose: The aim of this study was to determine the impact of isometric and isokinetic hip abductor muscle strength on the quality of maintaining static balance in healthy subjects. Methods: The study enrolled 51 healthy women aged 18–25. Balance assessment was carried out according to the M-CTSIB protocol and Single Leg Stance Test (with eyes open and closed) using the Biodex Balance System. An isokinetic evaluation conducted at 30 °/s and an isometric evaluation of the hip abductors were performed with the Humac Norm system. Results: Regression analysis for Sway Index (SW) and Stability Index (ST) in bipedal standing showed a significant importance of the presence of visual feedback (RSW EO = –0.922; p < 0.0001; RST EO = –0.613; p = 0.0493), and unstable surface (RSW US = 1.253; p < 0.0001; RSW US = 2.547; p < 0.0001). Regression analysis for single-leg stance showed correlations between the following indices: overall sway index (OR) in single-leg stance, the antero-posterior (AP) sway index and the medio-lateral (ML) sway index on the one hand and isometric abduction time to peak torque (ROR TPT = 0.769; p = 0.0005; RAP TPT = 0.565; p = 0.008; RML TPT = –1.74; p < 0.05, respectively) as well as the test conditions on the other. Conclusions: Physiological activation of the hip abductors may be important for physiological maintenance of postural balance in young people, in both leg standing as well as in single-leg stance. The present results warrant prospective, randomized studies of larger groups that are diversified with regard to age and gender of the participants.