Evidence of movement variability patterns during a repetitive pointing task until exhaustion

Human movement is characterized by its variability: the same task never performed twice in exactly way. This variability believed to play a functional role performance and adaptability, as well preventing musculoskeletal damage. article focuses on time-evolution of throughout repetitive pointing until exhaustion. The kinematics 13 subjects performing analyzed. Principal Component Analysis joint angles identifies coordinations for each cycle, cycle-by-cycle comparison highlights variability. Non-supervised clustering reveals that adopt successive coordination patterns at an intra-individual level. Inter-individual number type such patterns: from 3 5 patterns, mobilizing trunk, shoulder upper limbs differently. Movement exists even seemingly basic constrained task. It appears very early stages fatigue onset, may correspond adaptative responses performance. observation should encourage workstation designers better account order preserve operators' health safety.