Validity and reliability of skinfold measurement in assessing body fatness of Chinese children.

BACKGROUND Validity and reliability of skinfold equations in estimating body fat in Chinese Children has not been documented. OBJECTIVE Using Air Displacement Plethysmography (ADP) as a criterion, the validity and reliability of skinfold (SKF) measurement in predicting percent body fat (% fat) of Chinese children in Hong Kong were evaluated. DESIGN 230 Chinese children in Hong Kong were recruited to participate in measurements of ADP, body height and weight, waist and arm circumferences, and skinfold (SKF) from different body sites. A sub-sample of 41 participants was asked to take an additional measurement of Dual Energy X-ray Absorptiometry (DXA). % fat was measured from ADP, DXA, and estimated from Slaughter SKF equations. RESULTS internal consistency of SKF and ADP measurements were very high (r>or=0.988). Significant difference was found between % fat Slaughter and % fat ADP (p<0.05). The Slaughter equations slightly underestimate %fat (boys: 1.52%; girls: 1.84%). The slope of the regression line for boys and both the slope and intercept of regression line for prepubescent girls were significantly different from the line of identity. Subsequent stepwise regression found the best model for boys includes predictors of height, and Sigma3SKF (triceps, calf, and suprailiac) (R2=0.88, see=3.70), and that for girls includes height, Sigma2SKF (triceps and calf), and waist circumference (R2=0.71, see=3.38). The most convenient model for both genders required only triceps and age (boys: R2=0.81, see=4.67; girls: R2=0.63, see=3.77). CONCLUSIONS Skinfold measurements provide valid and reliable %fat estimation in Chinese children. However, the application of Slaughter equations in Chinese children is questionable. Alternative skinfold models are proposed.