Three-Dimensional Kinematic Characterization of An Object Pick-Up Task Using Motion Capture

The object pick-up task is a fundamental activity of daily living that integrates trunk, lower- and upper-limb coordination, balance, and visuomotor control within a single, ecologically valid movement. Despite its relevance, standardized protocols for quantitatively assessing object pick-up strategies using full-body motion capture remain limited. The goal of this protocol is to demonstrate a standardized method for capturing and analyzing the object pick-up task using full-body three-dimensional motion capture and to illustrate how different movement strategies can be identified and classified. The protocol details participant preparation, comprehensive marker placement, task execution, and representative kinematic analyses. Thirty participants performed the object pick-up task, during which fourteen kinematic variables were collected. Movement strategies were classified into squat-dominant, hinge-dominant, and hybrid patterns representing distinct and intermediate approaches along a continuum of movement strategies. Representative results demonstrate clear differences in joint kinematics between strategy groups, particularly at the knee and ankle, with additional contributions from torso motion. Differences between dominant and non-dominant hand conditions further illustrate the task's sensitivity to compensatory movement adaptations. This protocol provides a practical and reproducible framework for assessing object pick-up strategies and whole-body coordination during functional movement.