Background: Heavy loading of the spine may induce musculoskeletal problems in children. Local surveys reported frequent overloading of school bags carried by primary school children. The effect of an overweight school bag on the child's lung function has not been reported.
Aims: To investigate the effect of shoulder-girdle loading on forced expiratory lung volumes in primary school children and to compare this effect with that of an assumed kyphotic posture.
Study design and subjects: Forty-three primary school children, mean age 9.6 years underwent spirometry lung-function measurements, while adopting the following five conditions in random order: free standing; kyphotic standing; standing wearing a backpack weighing 10%, 20% and 30% of their body weight.
Outcomes measures: Forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEF).
Results: There were no significant differences in FEV1 and FVC between free standing and the 10% body weight load. However, both FEV1 and FVC decreased significantly when the student adopted the kyphotic posture and when the load in the backpack was increased to 20% and 30% of body weight.
Conclusions: This study demonstrates a restrictive effect on lung volumes when a school-bag load is heavier than 10% of a child's body weight. Our results also confirm the detrimental effect of a kyphotic posture on pulmonary mechanics and the necessity for health-care professionals to advocate proper postural advice to school children, teachers and parents.