Validity of bioelectrical impedance measurement in predicting fat-free mass of Chinese children and adolescents.
BACKGROUND
The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents.


METHODS
A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz between the hand and the foot. The criterion measure of FFM was also employed using dual-energy X-ray absorptiometry (DEXA). FFM estimated from 24 published BIA equations was cross-validated against the criterion measure from DEXA. Multiple linear regression was conducted to examine alternative BIA equation for the studied population.


RESULTS
FFM estimated from the 24 published BIA equations yielded high correlations with the directly measured FFM from DEXA. However, none of the 24 equations was statistically equivalent with the DEXA-measured FFM. Using multiple linear regression and cross-validation against DEXA measurement, an alternative prediction equation was determined as follows: FFM (kg)=1.613+0.742×height (cm)2/impedance (Ω)+0.151×body weight (kg); R2=0.95; SEE=2.45 kg; CV=6.5, 93.7% of the residuals of all the participants fell within the 95% limits of agreement.


CONCLUSIONS
BIA was highly correlated with FFM in Chinese children and adolescents. When the new developed BIA equations are applied, BIA can provide a practical and valid measurement of body composition in Chinese children and adolescents.
School of Kinesiology, Shanghai University of Sport, Shanghai, China (mainland).
Lin
L
Wang
Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Hong Kong, Hong Kong.
Stanley Sai-chuen
SS
Hui
Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Hong Kong, Hong Kong.
Stephen Heung-sang
SH
Wong
D015502:Absorptiometry, Photon; D050154:Adiposity; D000293:Adolescent; D044466:Asian People; D002648:Child; D002681:China; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012741:Sexual Maturation; D055815:Young Adult