Standing vs. side-lying and supine: a comparison of hip torque collection methodologies using the Biodex system

Maximum isometric joint torque can be used to evaluate muscle strength and tune computational models in biomechanics. However, variability in joint and body positioning complicates the interpretation of hip torque data. This study aimed to compare standing and side-lying/supine body positions during hip maximum voluntary isometric contractions across abduction, adduction, flexion, and extension. Subjects performed isometric hip torque trials using a Biodex dynamometer, with surface electromyography monitoring muscle activation in select hip muscles. Significant differences in normalized torque values were observed between standing and side-lying/supine positions, with standing producing higher torques in adduction and extension and side-lying favoring abduction. Muscle activation analyses revealed statistically significant biceps femoris activation during standing extension. Standardized protocols are essential for enhancing data consistency and advancing applications in biomechanics. The standing position's functional relevance and consistent torque production for movements like extension suggest its suitability for clinical and research applications.