title: Gender-age environmental associates of middle school students' low back pain.
abstract: OBJECTIVE
  The purpose of this study was to describe adolescents' low back pain, investigate its prevalence and explore its associations with backpack load, time spent carrying loads, time sitting, and time playing sports, to determine whether relationships exist among these variables.
  
  
  METHODS
  One hundred urban middle school students in Manchester, New Hampshire completed a questionnaire (55% response rate). Participants were between 13-14 years old. Weights of students, loaded backpacks, backpack contents, and students' heights were measured separately.
  
  
  RESULTS
  Eighty-nine percent of the participants wore the two-straps backpack. Over eighty percent of them preferred to carry the load over two shoulders. The average load weighed 4.9 kg (approximating 9.6% of the participants' body weight). There was a significant association found between backpack carrying time and adolescent low back pain.
  
  
  CONCLUSIONS
  Daily backpack carrying is a frequent cause of musculoskeletal discomfort for adolescents. The association between backpack carrying time and low back pain may provide the impetus for parents, teachers, and school administrators to decrease the prolonged carrying of backpacks. Further investigations should be conducted to evaluate the intervention effectiveness after implementation of controls.
authors.affiliation: Boston University, Boston, MA, USA.
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Chiang
authors.forename: Karen
authors.initials: K
authors.lastname: Jacobs
authors.forename: Gael
authors.initials: G
authors.lastname: Orsmond
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D009513:New Hampshire / Q000453:epidemiology; D012737:Sex Factors; D014481:United States