Relation of bone mineral density and content to mineral content and density of the fat-free mass

• Published in: Journal of applied physiology (1985) 2001-11, Vol.91 (5), p.2166-2172
• Main Authors: Evans, Ellen M, Prior, Barry M, Arngrimsson, Sigurbjorn A, Modlesky, Christopher M, Cureton, Kirk J
• Format: Article
• Language: English
• Subjects: Absorptiometry, Photon; Adult; Biological and medical sciences; Body Composition - physiology; Body Water - physiology; Bone and Bones - chemistry; Bone and Bones - metabolism; Bone Density - physiology; Bones; Continental Population Groups; Densitometry; Density; Female; Fundamental and applied biological sciences. Psychology; Gender; Humans; Male; Minerals; Minerals - metabolism; Physical fitness; Physical Fitness - physiology; Race; Sex Characteristics; Skeleton and joints; Space life sciences; Sports - physiology; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2001.91.5.2166

Departments of Exercise Science and Foods and Nutrition, University of Georgia, Athens, Georgia 30602-6554 Differences in the mineral fraction of the fat-free mass (M FFM ) and in the density of the FFM (D FFM ) are often inferred from measures of bone mineral content (BMC) or bone mineral density (BMD). We studied the relation of BMC and BMD to the M FFM and D FFM in a heterogeneous sample of 216 young men ( n  = 115) and women ( n  = 101), which included whites ( n  = 155) and blacks ( n   = 61) and collegiate athletes ( n  = 132) and nonathletes ( n  =   84). Whole body BMC and BMD were determined by dual-energy X-ray absorptiometry (DXA; Hologic QDR-1000W, enhanced whole body analysis software, version 5.71). FFM was estimated using a four-component model from measures of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by DXA. There was no significant relation of BMD to M FFM ( r  = 0.01) or D FFM ( r  =   0.06) or of BMC to M FFM ( r  =  0.11) and a significant, weak negative relation of BMC to D FFM ( r  =  0.14, P  = 0.04) in all subjects. Significant low to moderate relationships of BMD or BMC to M FFM or D FFM were found within some gender-race-athletic status subgroups or when the effects of gender, race, and athletic status were held constant using multiple regression, but BMD and BMC explained only 10-17% of the variance in M FFM and 0-2% of the variance in D FFM in addition to that explained by the demographic variables. We conclude that there is not a significant positive relation of BMD and BMC to M FFM or D FFM in young adults and that BMC and BMD should not be used to infer differences in M FFM or D FFM . body composition; bone mineral; bone density; densitometry; dual-energy X-ray absorptiometry; multicomponent models