Fatigue-induced increase in movement variability does not come at a cost of worse performance in a repetitive pointing task
(English)In: PLoS ONE, ISSN 1932-6203Article in journal (Refereed) Submitted
Neuromuscular strategies employed in multijoint movements during repetitive motion-induced fatigue are still unclear, and movement variability may present a novel way to understand the compensatory control mechanisms that occur during fatigue. The aim of this study was to assess changes in shoulder and elbow joint kinematic variabilities and shoulder-elbow coordination variability associated with neck-shoulder fatigue, and whether these changes affected the spatio-temporal aspects of task performance. Nineteen healthy young adults continuously performed a repetitive pointing task between two targets placed in front of them at shoulder height at 1 Hz until fatigue (Borg CR10 rating of 8). Shoulder and elbow kinematics were recorded and used to compute shoulder abduction-adduction and elbow flexion-extension joint angles, and fingertip trajectories were used to compute the movement time and 3D spatial coordinates of the endpoint in each repetitive pointing movement cycle. Cycle-to-cycle movement variability of the shoulder and elbow joint angles from 15 consecutive forward pointing movements and cycle-to-cycle variability of continuous relative phase between the shoulder and elbow joint angles were compared between the first (baseline) and last (fatigue-terminal) minutes of performance. Shoulder kinematic variability and shoulder-elbow coordination variability were found to significantly increase with fatigue (by 60% and 30% of their respective baseline values). However, movement timing errors and spatial variability of the endpoint were found to be unchanged with fatigue. Results suggest that fatigue-related increase in shoulder variability may have been compensated by changes in shoulder-elbow coordination with an overall task performance objective and associated hierarchical control mechanisms.
Place, publisher, year, edition, pages
multijoint movements, arm kinematics, fatigue, coordination variability, relative phase, performance metrics
Environmental Health and Occupational Health
IdentifiersURN: urn:nbn:se:hig:diva-20099OAI: oai:DiVA.org:hig-20099DiVA: diva2:846331
FunderForte, Swedish Research Council for Health, Working Life and Welfare, 2011-0075