title: The most physically active Danish adolescents are at increased risk for developing spinal pain: a two-year prospective cohort study.
abstract: BACKGROUND
  The overall aim of this study was to determine to what extent objectively measured physical activity in a school-based sample aged 11-13 years predicted incident cases of spinal pain (neck pain, mid back pain or low back pain) over the following 2 years.
  
  
  METHODS
  Data were collected at baseline (2010) and 2 years later in a school-based prospective cohort study. Spinal pain was assessed via an e-survey that the participants completed during school time. Participants who, at baseline, reported never having had spinal pain were included in the study. An incident case of spinal pain was defined as a report of pain in at least one spinal area at follow-up. Physical activity was measured objectively using the Actigraph GT3X Triaxial Activity Monitor for 1 week.
  
  
  RESULTS
  Objectively measured sedentary activity, moderate-to-vigorous physical activity and vigorous physical activity were generally not predictive of the 2-year incidence of spinal pain. However, 10% of participants with the highest proportion of the day spent in vigorous physical activity were at increased risk of reporting spinal pain at follow-up with a relative risk (RR) of 1.44 (95% CI 1.09 to 1.91). For the overall physical activity, the RR was 1.03 (95% CI 1.01 to 1.05) for reporting spinal pain at follow-up.
  
  
  CONCLUSIONS
  In general, physical activity did not affect the risk of spinal pain during follow-up, but the 10% most active adolescents were at increased risk of developing spinal pain. Thus, vigorous physical activity appears to be a risk factor for spinal pain in adolescents.
authors.affiliation: Department of Sports Science and Clinical Biomechanics, Faculty of Health Science , University of Southern Denmark , Odense , Denmark.
authors.forename: Ellen
authors.initials: E
authors.lastname: Aartun
authors.affiliation: Department of Sports Science and Clinical Biomechanics, Faculty of Health Science, University of Southern Denmark, Odense, Denmark; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Boyle
authors.affiliation: Department of Sports Science and Clinical Biomechanics, Faculty of Health Science, University of Southern Denmark, Odense, Denmark; Nordic Institute of Chiropractic and Clinical Biomechanics, Odense, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Hartvigsen
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences , University of Sydney , Sydney, New South Wales , Australia.
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Ferreira
authors.affiliation: George Institute for Global Health, Sydney Medical School, University of Sydney , Sydney, New South Wales , Australia.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Maher
authors.affiliation: George Institute for Global Health, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Institute of Bone and Joint Research, The Kolling Institute, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Manuela L
authors.initials: ML
authors.lastname: Ferreira
authors.affiliation: Department of Sports Science and Clinical Biomechanics, Faculty of Health Science, University of Southern Denmark, Odense, Denmark; Nordic Institute of Chiropractic and Clinical Biomechanics, Odense, Denmark.
authors.forename: Lise
authors.initials: L
authors.lastname: Hestbaek
keywords: Accelerometer; Adolescent; Physical activity; Spine