Effects of arousal and valence on standing kinematics and kinetics in young men: An approach using a motion capture system.

The emotional impact on body kinematics and kinetics during quiet standing was investigated using a motion capture system. Twenty-two participants stood on a force plate while viewing affective pictures for 72 s. The task was repeated six times under different picture conditions categorized by arousal (High and Low) and valence (Unpleasant, Neutral, and Pleasant). We analyzed variabilities of the center of mass, lower-limb joint angles (ankle, knee, and hip), and joint torques. Additionally, breathing parameters, including tidal volume, breathing rate, and minute ventilation, were estimated based on abdominal movements. The results showed that valence significantly influenced postural kinematics and kinetics, with unpleasant emotions reducing variabilities of the center of mass, ankle angle, and ankle torque, implying ankle-driven postural control. Additionally, pleasant emotions increased breathing rate. On the other hand, high arousal states increased tidal volume and minute ventilation compared to low arousal states. These findings suggest that emotional states manifest as changes in body kinematics and kinetics during quiet standing, extending upon traditional center of pressure (COP)-based reports. Our study provides new insights into emotional effects on physical responses and highlights the utility of standing parameters measured by motion capture systems for emotional detection.