title: The size and structure of arm movement variability decreased with work pace in a standardised repetitive precision task.
abstract: Increased movement variability has been suggested to reduce the risk of developing musculoskeletal disorders caused by repetitive work. This study investigated the effects of work pace on arm movement variability in a standardised repetitive pipetting task performed by 35 healthy women. During pipetting at slow and fast paces differing by 15%, movements of arm, hand and pipette were tracked in 3D, and used to derive shoulder and elbow joint angles. The size of cycle-to-cycle motor variability was quantified using standard deviations of several kinematics properties, while the structure of variability was quantified using indices of sample entropy and recurrence quantification analysis. When pace increased, both the size and structure of motor variability in the shoulder and elbow decreased. These results suggest that motor variability drops when repetitive movements are performed at increased paces, which may in the long run lead to undesirable outcomes such as muscle fatigue or overuse.
authors.affiliation: a Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies , University of Gävle , Gävle , Sweden.
authors.forename: Divya
authors.initials: D
authors.lastname: Srinivasan
authors.forename: Afshin
authors.initials: A
authors.lastname: Samani
authors.forename: Svend Erik
authors.initials: SE
authors.lastname: Mathiassen
authors.forename: Pascal
authors.initials: P
authors.lastname: Madeleine
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D012090:Cumulative Trauma Disorders / Q000517:prevention & control; D004551:Elbow Joint / Q000502:physiology; D005260:Female; D006225:Hand / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D009068:Movement / Q000502:physiology*; D012782:Shoulder / Q000502:physiology; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: Fitts’ law; cyclic movements; kinematics; linear and non-linear variability; motor control