Open Access Research article

Validity of new child-specific thoracic gas volume prediction equations for air-displacement plethysmography

Paul B Higgins1, Analiza M Silva2, Luis B Sardinha2, Holly R Hull3, Michael I Goran4, Barbara A Gower1 and David A Fields56*

Author Affiliations

1 Department of Nutrition Sciences, University of Alabama at Birmingham, AL, USA

2 Exercise and Health Laboratory, Faculty of Human Movement, Technical University of Lisbon, Portugal

3 Department of Health and Exercise Science, University of Oklahoma, OK, USA

4 Department of Preventive Medicine, University of Southern California, CA, USA

5 Department of Pediatrics, Children's Medical Research Institute's Metabolic Research Center, University of Oklahoma Health Science Center, OK, USA

6 Assistant Professor,University of Oklahoma Health Science Center, School of Medicine,Department of Pediatrics, OUCP Diabetes & Endocrinology, 940 NE 13th Street, CH 2B2426, OKC, OK 73104, USA

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BMC Pediatrics 2006, 6:18  doi:10.1186/1471-2431-6-18

Published: 5 June 2006



To determine the validity of the recently developed child-specific thoracic gas volume (TGV) prediction equations for use in air-displacement plethysmography (ADP) in diverse pediatric populations.


Three distinct populations were studied: European American and African American children living in Birmingham, Alabama and European children living in Lisbon, Portugal. Each child completed a standard ADP testing protocol, including a measured TGV according to the manufactures software criteria. Measured TGV was compared to the predicted TGV from current adult-based ADP proprietary equations and to the recently developed child-specific TGV equations of Fields et al. Similarly, percent body fat, derived using the TGV prediction equations, was compared to percent body fat derived using measured TGV.


Predicted TGV from adult-based equations was significantly different from measured TGV in girls from each of the three ethnic groups (P < 0.05), however child-specific TGV estimates did not significantly differ from measured TGV in any of the ethnic or gender groups. Percent body fat estimates using adult-derived and child-specific TGV estimates did not differ significantly from percent body fat measures using measured TGV in any of the groups.


The child-specific TGV equations developed by Fields et al. provided a modest improvement over the adult-based TGV equations in an ethnically diverse group of children.