title: Influence of Work Pace on Upper Extremity Kinematics and Muscle Activity in a Short-Cycle Repetitive Pick-and-Place Task.
abstract: OBJECTIVE
  This study investigated the extent to which controlled changes in work pace in a cyclic pick-and-place task influence upper extremity kinematics and muscle activity, and whether an effect depends on working height.
  
  
  METHODS
  Thirteen participants performed the task for 4 min at each of five work paces ranging from 8 to 12 cycles·min-1 in each of two experimental conditions where the hand was moved horizontally with an average upper arm elevation of 30° and 50°, respectively. For each work cycle, we calculated the average and standard deviation of the upper arm elevation angle and the activity of the trapezius and deltoid muscles, as well as the angular peak velocity. We summarized these seven variables by calculating averages across cycles and cycle-to-cycle variabilities.
  
  
  RESULTS
  At 30° arm elevation, pace significantly influenced within-cycle angle variation, cycle-to-cycle variability of the average angle, angular peak velocity, and cycle-to-cycle variability of peak velocity. However, only angular peak velocity increased monotonically across all paces from 8 to 12 cycles·min-1). Average activity in the trapezius and the deltoid were the only muscle activity variables to increase consistently with pace. These effects of work pace did not change with working height.
  
  
  CONCLUSIONS
  The present study did not find any consistent work pace effect on upper extremity kinematics and muscle activity, in spite of a comprehensive empirical basis compared to previous literature. While our results suggest that work pace may not be of critical concern in an occupational health context, we encourage further studies verifying or disproving this notion.
authors.affiliation: Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research, University of Gävle, Kungsbäcksvägen 47, 801 76 Gävle, Sweden.|TNO Leiden, Schipholweg 77, 2316 ZL Leiden, The Netherlands.|Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, VU University Amsterdam, MOVE Research Institute Amsterdam, Van der Boechorststraat 9, Amsterdam 1081BT, The Netherlands.|Institute of Occupational and Social Medicine and Health Services Research, Faculty of Medicine, University Hospital, Eberhard Karls University Tübingen, Wilhelmstraße 27, 72074 Tübingen, Germany.
authors.forename: Tessy
authors.initials: T
authors.lastname: Luger
authors.affiliation: Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research, University of Gävle, Kungsbäcksvägen 47, 801 76 Gävle, Sweden.
authors.forename: Svend Erik
authors.initials: SE
authors.lastname: Mathiassen
authors.affiliation: Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research, University of Gävle, Kungsbäcksvägen 47, 801 76 Gävle, Sweden.|Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University, 1145 Perry Street, Blacksburg, VA 24061, USA.
authors.forename: Divya
authors.initials: D
authors.lastname: Srinivasan
authors.affiliation: TNO Leiden, Schipholweg 77, 2316 ZL Leiden, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Bosch
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology*; D012090:Cumulative Trauma Disorders / Q000503:physiopathology* / Q000517:prevention & control; D057645:Deltoid Muscle / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D060051:Occupational Injuries / Q000517:prevention & control; D064171:Superficial Back Muscles / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: motor variability; muscle activity; upper arm elevation; work pace