title: Guidelines for schoolbag carriage: An appraisal of safe load limits for schoolbag weight and duration of carriage.
abstract: BACKGROUND
  There is no global agreement on a schoolbag weight limit and little assessment of its utility. The duration of carriage is another factor yet there is no previous systematic assessment of the utility of cut-off values for it in identifying schoolbag-related discomfort.
  
  
  OBJECTIVE
  The objectives were to establish if there was a threshold for musculoskeletal discomfort based on (i) percentage bodyweight (% BW) of the schoolbag; (ii) duration of carriage; or (iii) combined % BW and duration.
  
  
  METHODS
  Using data from 462 primary school children, a novel experimental approach was used to explore the utility of conventional schoolbag weight limit guidelines and duration of carriage. A receiver operating characteristic (ROC) curve was constructed to examine the predictive performance of schoolbag weight and duration of carriage.
  
  
  RESULTS
  The mean schoolbag weight (4.8±1.43  kg) represented a mean 12.4±4.18% BW. Only 30.7% of the sample carried schoolbags that were ≤10% BW. The majority (76%) carried schoolbags to school for ≤10 minutes. No % BW, duration of carriage or mechanical burden criterion provided a threshold cut-off point for accurately predicting schoolbag-related discomfort.
  
  
  CONCLUSIONS
  Guidelines for safe schoolbag carriage that are based on mechanical factors alone could not be upheld. The association between duration of carriage and back discomfort warrants further investigation.
authors.affiliation: Discipline of Physiotherapy, School of Medicine, Trinity College, Dublin, Ireland.
authors.forename: Sara
authors.initials: S
authors.lastname: Dockrell
authors.affiliation: School of Public Health, Physiotherapy and Sports Science, Health Sciences Centre, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Catherine
authors.initials: C
authors.lastname: Blake
authors.affiliation: Mechanical & Manufacturing Engineering, Trinity College, Dublin, Ireland.
authors.forename: Ciaran
authors.initials: C
authors.lastname: Simms
mesh_terms: D001835:Body Weight; D002648:Child; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D017770:Lifting / Q000009:adverse effects*; D008297:Male; D059352:Musculoskeletal Pain / Q000209:etiology*; D017288:Pain Threshold; D012372:ROC Curve; D013997:Time Factors; D016474:Weight-Bearing
keywords: Schoolbag; duration of carriage; guidelines; weight limit