Preliminary analysis on the cervicothoracic angular velocity during forward bending and backward return task

Improper posture, presence of spinal disorders or assessment of postural stability require specific monitoring systems, applicable in static and dynamic conditions. Different methods are available for the analysis of the posture, ranging from the visual observation in clinical practice to the tridimensional reconstruction of the spine with optical motion capture systems. Wearable devices based on inertial sensors may be adopted for the continuous measurement of the subject posture, not only during rehabilitative exercises, but also during daily activities. Equal attention should be reserved both to the choice of the sensor and to the understanding of which physiological parameters are best being monitored. In this work, we propose a system consisting of a magneto-inertial measurement unit (MIMU) to monitor the velocity profile of the cervicothoracic spine segment while performing forward bending and backward return task. The MIMU was placed on the back of four volunteers (two women and two men). The time series of the angular velocity of the cervicothoracic region has been compared with the data provided by a motion capture system (MoCap), which is able to track the tridimensional positions of the reflective markers attached to the skin at specific anatomical landmarks, ensuring adaptation to the gender-related anatomy. The proposed system, compared to the reference, presents a relative root mean square error (RMSE) spanning from 3.6% to 4.8% of the total measured range of velocities. These results show that the proposed wearable system could be used for the health assessment of the posture of any subject without gender and age restrictions during daily activities.