title: Age comparisons of bone density and geometry in men.
abstract: OBJECTIVE
  The purposes of this study were to examine tibia bone density and geometry in young and middle aged men, and to explore relationships between pQCT- and DXA-derived body composition variables.
  
  
  METHODS
  Healthy males (18-30 years old, n=31; 50-64 years old, n=37) had their total body areal bone mineral density (aBMD) and body composition measured with Dual Energy X-ray Absorptiometry (DXA). Volumetric bone characteristics, muscle cross-sectional area (MCSA) and fat cross-sectional area (FCSA) of the leg were measured with peripheral Quantitative Computed Tomography (pQCT).
  
  
  RESULTS
  Young men were significantly (p<0.05) lighter and had less fat mass than older men. Total volumetric BMD (vBMD) at 66% of the tibia length was significantly lower (p<0.05) in older men. Bone-free lean body mass values were useful predictors of total and cortical area and content (R(2)=0.338-0.467). MCSA was more predictive of leg BFLBM than total body BFLBM, and those relationships were stronger in older men.
  
  
  CONCLUSIONS
  Differences in tibial bone area and density existed between young and middle-aged men, and relationships between pQCT- and DXA-derived body composition variables were age-dependent.
authors: Bone Density Research Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma 73019, USA.
authors: V D
authors: VD
authors: Sherk
authors: M
authors: M
authors: Karabulut
authors: M G
authors: MG
authors: Bemben
authors: D A
authors: DA
authors: Bemben
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D009929:Organ Size; D012044:Regression Analysis; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed