title: Percentage of body weight carried by students in their school backpacks.
abstract: OBJECTIVE
  To determine the percentage of body weight represented by backpacks and the types of backpacks carried by elementary school students.
  
  
  METHODS
  A cross-sectional study was conducted in three elementary schools in central Texas. All students in kindergarten through fifth grade were invited to participate. A letter, with no direct mention of backpack weighing, was sent to each parent for written consent. Student weights and heights and their backpack weights were measured by trained research assistants.
  
  
  RESULTS
  The mean backpack weights, which increased significantly with increasing grade level, varied significantly by school, backpack type, day of week, body mass index, and race/ethnicity. The backpack loads represented an average of 8.2% (95% confidence interval, 7.8-8.5) of student body weights but increased significantly with increasing grade level, from 6.2% among kindergarteners to 12.0% among fifth graders. Twenty-six percent of students carried backpacks that weighed at least 10% of their body weights. A total of 25 students (3.5%) had backpacks with wheels. Wheeled backpack users were significantly older and more likely to be girls or from school B. Concern about weight was the most popular reason cited for using a wheeled backpack.
  
  
  CONCLUSIONS
  Backpack loads represent a significant percentage of body weight of this sample of students aged 5-12 yr. Some students are already using wheeled backpacks, which may have their own hazards.
authors.affiliation: Department of Family and Community Medicine, Scott and White Memorial Hospital, Texas A&M University System Heatlh Science Center, College of Medicine, Temple 76504, USA.
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Forjuoh
authors.forename: Bryan L
authors.initials: BL
authors.lastname: Lane
authors.forename: John A
authors.initials: JA
authors.lastname: Schuchmann
mesh_terms: D001415:Back; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017770:Lifting / Q000009:adverse effects*; D008297:Male; D012574:Schools; D013334:Students; D016474:Weight-Bearing / Q000502:physiology*