title: Associations between biopsychosocial factors and chronic upper limb pain among slaughterhouse workers: cross sectional study.
abstract: BACKGROUND
  Knowledge of factors associated with chronic pain is necessary for preventive strategies. The present study investigates biopsychosocial differences, with specific focus on rate of force development (RFD) and work ability, between workers with and without chronic upper limb pain.
  
  
  METHODS
  Eighty-two male slaughterhouse workers, 49 with chronic upper limb pain and 33 pain-free controls participated in the study. Maximal muscle strength, RFD, and muscle activity was determined from fast and forceful maximal voluntary contractions for the shoulder and hand. Participants filled out a questionnaire on work ability (work ability index), work disability (Work module of DASH questionnaire), fear avoidance, and self-rated health. Additionally, pressure pain threshold (PPT) was measured in muscles of the arm, shoulder and lower leg.
  
  
  RESULTS
  Muscle strength and RFD (determined within time intervals of 30, 50, 100, and 200 ms relative to onset of contraction) was 28 % and 58-78 % lower, respectively, in workers with chronic pain compared with pain-free controls, and paralleled by reduced muscle activity (all p < 0.001). Workers with chronic pain had lower PPT of the arm, shoulder and lower leg (p < 0.01), and reported impaired work ability index score and general health along with higher work disability and fear avoidance compared with controls (all p < 0.0001). No differences were observed between the groups in regard to age, BMI, physical activity level, job position and duration of slaughterhouse work (all p > 0.4).
  
  
  CONCLUSIONS
  Chronic upper limb pain was paralleled by reduced neuromuscular function of the shoulder and hand along with impaired work ability, work disability and general health. Future studies on chronic pain management at the workplace should carefully consider the biopsychosocial nature of pain when designing and implementing preventive strategies.
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, Copenhagen, Denmark. esu@nrcwe.dk.|Institute for Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark. esu@nrcwe.dk.
authors.forename: Emil
authors.initials: E
authors.lastname: Sundstrup
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, Copenhagen, Denmark.|Institute for Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark.
authors.forename: Markus D
authors.initials: MD
authors.lastname: Jakobsen
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, Copenhagen, Denmark.|Physical Activity and Human Performance Group, Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Brandt
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, Copenhagen, Denmark.|Institute for Sport and Clinical Biomechanics, Department of physical activity and health, University of Southern Denmark, Odense, Denmark.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Jay
authors.affiliation: Institute for Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkalle 105, Copenhagen, Denmark.|Physical Activity and Human Performance Group, Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Lars L
authors.initials: LL
authors.lastname: Andersen
mesh_terms: D000003:Abattoirs; D000328:Adult; D059350:Chronic Pain / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology*; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D016273:Occupational Exposure / Q000009:adverse effects*; D010147:Pain Measurement / Q000379:methods / Q000523:psychology*; D011584:Psychology; D034941:Upper Extremity / Q000473:pathology*