The impact of gravity on functional movements: kinematic insights and features selection

Abstract

AbstractExploring the impact of gravity on daily upper-limb movements is crucial for comprehending the complexities of upper-limb impairments. The present study delves into the relationship between the gravitational force and the functional aspects of upper-limb mobility. Starting from 9 pick-and-place tasks, hand trajectories of 24 healthy subjects were acquired using a motion capture system. Five in-use and two novel kinematic metrics were extrapolated by such trends and tested across conditions. Results suggest movements performed against and propelled by gravity lead to statistically significant changes in motor behaviour in terms of planning, smoothness, efficiency, and accuracy of the movement, underlining the need of differentiating the study of such movements in impaired subjects.Author summaryWhy was this study done?Gravitational force significantly influences the daily activities of individuals with full physical abilities.Disabilities affecting the upper limbs result in a loss of independence and self-care, necessitating proper rehabilitative attention.Many upper-limb assessments overlook object manipulation and lack appropriate quantitative scales.It is essential to study and characterize the proper motor behavior of healthy individuals during functional movements to establish reference measurements for those with impaired abilities.What did the research do and find?The study involved creating an experimental setup to characterize healthy upper-limb movements: a pick-and-place task was introduced, requiring participants to move objects in various directions with respect to gravity.Twenty-four healthy subjects were recruited, motion capture analysis was conducted to study hand kinematics.From hand displacements and velocities, five existing and two innovative kinematic features were chosen. A statistical analysis was performed to identify any impact of gravity on functional movementsResults confirmed that moving in the same direction of or against gravity does influence hand postural patterns during a pick-and-place task.What do these finding mean?The confirmed impact of gravity on hand postural patterns suggests that individuals with upper-limb disabilities may face additional challenges in executing functional movements. These insights underscore the importance of considering gravitational forces in rehabilitation strategies for those with upper-limb impairments.The identified kinematic features provide valuable markers for assessing and tailoring interventions aimed at improving hand function. Overall, these findings contribute essential knowledge to the development of targeted rehabilitation approaches for individuals with upper-limb disabilities.In the future, the proposed set-up should be tested as a tool for the assessment of functional restoration in upper-limb impaired subjects.