title: Changes in the amount and structure of motor variability during a deboning process are associated with work experience and neck-shoulder discomfort.
abstract: In this field study, the size and structure of kinematics variability were assessed in relation to experience and discomfort during a deboning task. Eighteen workers divided in groups with low/high experience and with/without neck-shoulder discomfort participated. Standard deviation and coefficient of variation (amount of variability), as well as approximate entropy and sample entropy (complexity) and, correlation dimension (dimensionality) were computed for head-shoulder, shoulder-hip and elbow-hip displacement in the vertical direction. A longer work experience was associated with shorter work cycle duration and decreased amount of variability while complexity increased for the head-shoulder displacement, P<0.05. Shorter work cycle, lower amount of variability and, lower dimensionality for the head-shoulder displacement were found in relation to discomfort, P<0.05. While the amount of variability, complexity and dimensionality increased for the elbow-hip displacement, P<0.05. These findings suggest a functional role of experience via learning effects and discomfort through compensatory mechanisms on the size and structure of motor variability.
authors.affiliation: Laboratory for Ergonomics and Work-related Disorders, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7, Bldg. D-3, DK 9220 Aalborg, Denmark. pm@hst.aau.dk
authors.forename: P
authors.initials: P
authors.lastname: Madeleine
authors.forename: T M T
authors.initials: TM
authors.lastname: Madsen
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D006804:Ergonomics; D006801:Humans; D016014:Linear Models; D008297:Male; D008462:Meat-Packing Industry; D009048:Motor Skills; D019838:Neck Injuries / Q000453:epidemiology / Q000209:etiology; D019547:Neck Pain / Q000453:epidemiology / Q000209:etiology*; D017711:Nonlinear Dynamics; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health; D011187:Posture; D020069:Shoulder Pain / Q000453:epidemiology / Q000209:etiology*