Differences in motor variability among individuals performing a standardized short-cycle manual task

• Published in: Human movement science Vol. 51; pp. 17 - 26
• Main Authors: Sandlund, Jonas, Srinivasan, Divya, Heiden, Marina, Mathiassen, Svend Erik
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2017
• Subjects: Adult; Between-subjects riability; Between-subjects variability; Biomechanical Phenomena - physiology; Day-to-day variability; Elbow - physiology; Elbow Joint; Female; Health-Promoting Work; Humans; Hälsofrämjande arbete; Individual differences; Individuality; Kinematics; Male; Motor Skills - physiology; Principal Component Analysis; Psychomotor Performance - physiology; Reference Values; Repetitive task; Shoulder - physiology; Stereotyped Behavior - physiology; Day-to-day variability; Between-subjects variability; Repetitive task; Kinematics; Individual differences; Principal component analysis
• ISSN: 0167-9457; 1872-7646; 1872-7646
• DOI: 10.1016/j.humov.2016.10.009

•Cycle-to-cycle motor variability was substantial in females repeating a pipetting task.•Motor variability assessed using PCA on kinematic variables differed between days.•Motor variability also differed consistently between subjects doing the pipetting task.•Results support the hypothesis that motor variability may be a personal trait. Motor variability (MV) has been suggested to be a determinant of the risk for developing musculoskeletal disorders in repetitive work. In this study we examined whether individuals consistently differed in the extent of motor variability when performing a standardized short-cycle manual task. On three separate days, arm kinematics was recorded in 14 healthy subjects performing a pipetting task, transferring liquid from a pick-up tube to eight target tubes with a cycle time of 2.8s. Cycle-to-cycle standard deviations (SD) of a large selection of shoulder and elbow kinematic variables, were processed using principal component analysis (PCA). Thereafter, between-subjects and between-days (within-subject) variance components were calculated using a random effects model for each of four extracted principal components. The results showed that MV differed consistently between subjects (95% confidence intervals of the between-subjects variances did not include zero) and that subjects differed consistently in MV between days. Thus, our results support the notion that MV may be a consistent personal trait, even though further research is needed to verify whether individuals rank consistently in MV even across tasks. If so, MV may be a candidate determinant of the risk of developing fatigue and musculoskeletal disorders in repetitive occupational work.