title: Impact of backpack load on ventilatory function among 9-12 year old Saudi girls.
abstract: OBJECTIVE
  To explore the backpack load as a percentile of body weight (BW) and its impact on ventilatory function including tidal volume (Vt), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF), and maximum voluntary ventilation (MVV) among 9-12 year old Saudi girls.
  
  
  METHODS
  This is a prospective, experimental study of 91 Saudi girls aged between 9-12 years from primary schools in Riyadh, Saudi Arabia. The study took place in King Saud University, Riyadh, Saudi Arabia between April 2012 and May 2012. Ventilatory function was measured under 2 conditions: a free standing position without carrying a backpack, and while carrying a backpack.
  
  
  RESULTS
  The backpack load observed was 13.8% of the BW, which is greater than the recommended limit (10% BW). All values of ventilatory function were significantly reduced after carrying the backpack (p<0.001) with the exception of FEV1/FVC (p>0.178). The reduction was observed even with the lowest backpack load (7.4% BW).
  
  
  CONCLUSIONS
  A significant reduction was reported for most of the ventilatory function parameters while carrying the backpack. This reduction was apparent even with the least backpack load (7.4% BW) carried by the participants. This study recommends that the upper safe limit of backpack load carried by Saudi girls aged 9-12 years should be less than 7.4% of BW.
authors.affiliation: Physical Therapy Department, Prince Sultan Military Medical City, Riyadh, Kingdom of Saudi Arabia. Tel. +966 (11) 4777714 Ext. 57968. E-mail: aalkatheri@psmmc.med.sa.
authors.forename: Abeer E
authors.initials: AE
authors.lastname: Al-Katheri
mesh_terms: D001415:Back; D001835:Body Weight; D002648:Child; D005260:Female; D006801:Humans; D011446:Prospective Studies; D012123:Pulmonary Ventilation / Q000502:physiology*; D012529:Saudi Arabia; D016474:Weight-Bearing / Q000502:physiology*