title: Task variation during simulated, repetitive, low-intensity work--influence on manifestation of shoulder muscle fatigue, perceived discomfort and upper-body postures.
abstract: Work-related musculoskeletal disorders are increasing due to industrialisation of work processes. Task variation has been suggested as potential intervention. The objectives of this study were to investigate, first, the influence of task variation on electromyographic (EMG) manifestations of shoulder muscle fatigue and discomfort; second, noticeable postural shoulder changes over time; third, if the association between task variation and EMG might be biased by postural changes. Outcome parameters were recorded using multichannel EMG, Optotrak and the Borg scale. Fourteen participants performed a one-hour repetitive Pegboard task in one continuous and two interrupted conditions with rest and a pick-and-place task, respectively. Manifestations of shoulder muscle fatigue and discomfort feelings were observed throughout the conditions but these were not significantly influenced by task variation. After correction for joint angles, the relation between task variation and EMG was significantly biased but significant effects of task variation remained absent.
  Comparing a one-hour continuous, repetitive Pegboard task with two interrupted conditions revealed no significant influences of task variation. We did observe that the relation between task variation and EMG was biased by posture and therefore advise taking account for posture when investigating manifestations of muscle fatigue in assembly tasks.
authors.affiliation: a MOVE Research Institute , Faculty of Human Movement Sciences, VU University Amsterdam , Amsterdam , The Netherlands.|b TNO , Leiden , The Netherlands.|c Body@Work, Research Centre of Physical Activity, Work and Health , TNO-VU/VUmc , Amsterdam , The Netherlands.
authors.forename: Tessy
authors.initials: T
authors.lastname: Luger
authors.affiliation: b TNO , Leiden , The Netherlands.|c Body@Work, Research Centre of Physical Activity, Work and Health , TNO-VU/VUmc , Amsterdam , The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Bosch
authors.affiliation: a MOVE Research Institute , Faculty of Human Movement Sciences, VU University Amsterdam , Amsterdam , The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Hoozemans
authors.affiliation: a MOVE Research Institute , Faculty of Human Movement Sciences, VU University Amsterdam , Amsterdam , The Netherlands.|b TNO , Leiden , The Netherlands.|c Body@Work, Research Centre of Physical Activity, Work and Health , TNO-VU/VUmc , Amsterdam , The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: de Looze
authors.affiliation: a MOVE Research Institute , Faculty of Human Movement Sciences, VU University Amsterdam , Amsterdam , The Netherlands.|d Laboratory for Biomechatronics and Biorobotics, Faculty of Mechanical, Maritime and Materials Engineering , Delft University of Technology , Delft , The Netherlands.
authors.forename: Dirkjan
authors.initials: D
authors.lastname: Veeger
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement; D018763:Muscle Fatigue; D018482:Muscle, Skeletal; D009140:Musculoskeletal Diseases; D009784:Occupational Diseases; D011187:Posture; D012782:Shoulder; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: multichannel electromyography; muscle fatigue; posture; shoulder; task variation