Development of head-trunk coordination measures for assessing sensorimotor function in laboratory and natural settings using wearable sensors

Stabilization of the head in space is important for postural and locomotion control. Disruptions in head-trunk coordination can impair functional performance during aging, pathophysiology, or exposure to altered sensory environment states such as spaceflight. Monitoring head-trunk coordination could aid in understanding the risks associated with sensorimotor impairment. The present study evaluated a custom algorithm developed from parameters of head-trunk coordination obtained from wearable sensors. Task performance of healthy adults during standard laboratory tasks both with and without physical restriction via a neck brace were assessed to develop the algorithm and motion thresholds. The algorithm was applied to 12 blinded 4-hr datasets to evaluate the reliability and sensitivity of the measures for identifying altered head-to-trunk coordination when a neck brace was worn during daily activities in a natural setting. The primary head-to-trunk coordination metrics showing high detection accuracy were the root mean square deviation between the angular velocity signals of the head and trunk, followed by the difference in the magnitude orientation. Additionally, the coherence of angular velocity along the X and Z global axes demonstrated good detection sensitivity. The present work lays the foundation for future applications, particularly in monitoring impaired head-trunk coordination in natural settings to provide valuable insights for rehabilitation.