Background <p>Prior hip joint position sense (JPS) studies have predominantly assessed it in a standing position, where compensatory movements in joints other than the hip may occur to maintain balance, complicating the isolation of the hip joint’s specific influence. This study aims to investigate joint position error (JPE) in hip flexion and abduction in the supine position under varying muscle contraction conditions (passive, active, and active with resistance) using readily available inertial measurement units.</p> Methods <p>JPE was measured using inertial measurement units during two kinematic motions—hip flexion and abduction—under three muscle contraction conditions: passive, active, and active with resistance. A target angle set at 50% of the participant’s maximal range of motion (MaxROM) was used, and JPE was calculated as the difference between the target and measured angles.</p> Results <p>JPE for flexion differed significantly from abduction. In abduction, JPE during passive contraction was significantly greater than during active conditions. Across both motions, the measured angles tended to increase progressively from passive to active with resistance.</p> Conclusion <p>Increased muscle loading required more effort, leading to overshoot in hip abduction, while hip flexion showed a similar trend without overshoot. These findings help clarify how hip proprioception differs by movement direction and muscle use, providing insight for improving proprioceptive training and motor control in rehabilitation.</p>