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Effects of Backpack Loading on the Pulmonary Capacities of Normal Schoolgirls and Those with Adolescent Idiopathic Scoliosis

Chow, Daniel H. K., PhD*; Ng, Xavier H. Y., MSc*; Holmes, Andrew D., PhD*; Cheng, Jack C. Y., MD; Yao, Fiona Y. D., PhD; Wong, M S., PhD*

doi: 10.1097/01.brs.0000184368.58262.d2

Study Design. A prospective evaluation of the effects of backpack carriage on the pulmonary function of schoolgirls without spinal deformity versus those with adolescent idiopathic scoliosis (AIS).

Objective. To establish if recommended backpack load limits for normal schoolchildren are also appropriate for study participants with AIS.

Summary of Background Data. The weight of schoolchildren’s backpacks are of concern because of effects including compromise of pulmonary function. Impaired pulmonary function is also found with AIS, but the effect of backpack carriage on the respiratory parameters of schoolchildren with AIS has not previously been examined.

Methods. Forced vital capacity (FVC), forced expiratory volume (FEV1), peak expiratory flow (PEF), and forced expiratory flow (FEF25–75%) were recorded in 17 girls (mean age, 12 years) with moderate AIS (Cobb angle, 26°–50°) and 18 girls (mean age, 11 years) without musculoskeletal deformity during carriage of a backpack loaded at 0%, 5%, 7.5%, 10%, 12.5%, and 15% body weight in random order. Absolute values and proportions of reference values were analyzed by repeated-measures analysis of variance.

Results. No interaction between load and group was found, indicating that backpack loading has a similar effect on the pulmonary function of both normal and AIS groups. However, all recorded pulmonary parameters were found to be significantly lower in the AIS than normal group, significantly so for the referenced FVC and PEF. A significant decrease in FVC and FEV1 was found with increasing backpack load, and the load at which these changes were found to be significant was lower than those established in previous studies.

Conclusions. Pulmonary function may be more sensitive to backpack load than previously considered, especially when study participants with AIS are being considered, and the recommended loading limit of 10% body weight may not be applicable to schoolgirls with AIS.

Carriage of a loaded backpack has a similar restrictive effect on the pulmonary capacities of schoolgirls as adolescent idiopathic scoliosis, and the combined effect of these two factors appears to follow a simple additive rule. Pulmonary function may be more sensitive to backpack load than previously considered, and as such the recommended load for normal subjects may not be appropriate for schoolgirls with adolescent idiopathic scoliosis.

From the Departments of *Health Technology and Informatics and †Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong; and ‡Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Hong Kong.

Acknowledgment date: April 26, 2005. First revision date: May 13, 2005. Acceptance date: May 18, 2005.

Supported by grant PolyU 5217/00 M from the Research Grants Council of the Hong Kong SAR, People’s Republic of China.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Institutional funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Daniel H. K. Chow, PhD, Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong; E-mail:

© 2005 Lippincott Williams & Wilkins, Inc.