Mineral and water content of the fat-free body: effects of gender, maturation, level of fatness, and age.
Variability associated with the effects of gender, level of fatness (LOF), maturation (ML), and age on the mineral (MFFB) and water (WFFB) content of the fat-free body (FFB) was investigated in 188 males and 144 females, aged 8 to 17 years. Measures of body density, bone mineral content, total body water, and skin-fold thicknesses were obtained. FFB was calculated using a multicomponent model based on body density and adjusting for variability in body water and mineral content. Subjects were classified by ML as prepubescent, pubescent, and postpubescent. Subjects were also grouped by LOF as lean, average, and obese based on percentile rankings from the age-related norms of the National Children and Youth Fitness Study. Least squares multiple regression analysis using weighted orthogonal contrasts to account for sample size differences revealed significant (p<.01) gender, ML, gender x LOF, and gender x ML effects for MFFB; however, no significant (p>.05) effects between, or within, gender were noted for WFFB. Significant ML, and nearly significant (p>.056) LOF x ML, effects were found for MFFB in the males. In contrast, only ML was significant within the female sample for MFFB. These results were upheld when age, rather than ML, was used in the analysis. The overall relative increase in MFFB across ML was greatest in the obese (17.4%, 9.3%) and least in the lean (11.3%, 6.3%) males and females, respectively. A significant increase in MFFB across ML was observed in both genders; however, the pattern and magnitude of increase is dependent upon LOF considered. Hence, consideration of gender, ML, LOF and age is essential in estimating body composition in children.
Slaughter
M H
MH
Physical Fitness Research Laboratory, Dept. of Kinesiology, Univ. of Illinois, Urbana-Champaign, Ill 61801, USA.
Christ
C B
CB
Stillman
R J
RJ
Boileau
R A
RA
D000273:Adipose Tissue / Q000378:metabolism; D000293:Adolescent; D000367:Age Factors; D001481:Basal Metabolism; D001823:Body Composition; D015992:Body Mass Index; D001834:Body Water; D001835:Body Weight; D015519:Bone Density; D002648:Child; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008903:Minerals / Q000378:metabolism*; D015999:Multivariate Analysis; D009765:Obesity; D012044:Regression Analysis; D012737:Sex Factors; D012885:Skinfold Thickness; D013997:Time Factors
D008903:Minerals