title: Muscle density predicts changes in bone density and strength: a prospective study in girls.
abstract: OBJECTIVE
  We sought to determine whether muscle density, an index of skeletal muscle fat content, was predictive of 2-year changes in weight-bearing bone parameters in young girls.
  
  
  METHODS
  Two-year prospective data from 248 girls, aged 8-13 years at baseline. Peripheral quantitative computed tomography was used to measure changes in bone strength indices (bone strength index [BSI, mg(2)/mm(4)] and strength-strain index [SSIp, mm(3)]) and volumetric bone mineral density [vBMD, mg/cm(3)] at distal metaphyseal and diaphyseal regions of the femur and tibia, as well as calf and thigh muscle density (mg/cm(3)), and muscle cross-sectional area (MCSA, mm(2)), indices of skeletal muscle fat content and muscle force production, respectively.
  
  
  RESULTS
  After controlling for potential confounders, greater gains in femur BSI (44%, P<0.002), total femur vBMD (114%, P<0.04) and femur trabecular vBMD (306%, P<0.002) occurred in girls in the lowest versus the highest groups of baseline thigh muscle density. Greater gains in tibial BSI (25%, P<0.03) and trabecular vBMD (190%, P<0.002) were also observed in the lowest versus the highest baseline calf muscle density groups.
  
  
  CONCLUSIONS
  Baseline muscle density is a significant predictor of changes in bone density and bone strength in young girls during a period of rapid skeletal development.
authors.affiliation: Department of Nutritional Sciences, University of Arizona, Tucson, AZ, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Laddu
authors.forename: J N
authors.initials: JN
authors.lastname: Farr
authors.forename: V R
authors.initials: VR
authors.lastname: Lee
authors.forename: R M
authors.initials: RM
authors.lastname: Blew
authors.forename: C
authors.initials: C
authors.lastname: Stump
authors.forename: L
authors.initials: L
authors.lastname: Houtkooper
authors.forename: T G
authors.initials: TG
authors.lastname: Lohman
authors.forename: S B
authors.initials: SB
authors.lastname: Going
mesh_terms: D050154:Adiposity / Q000502:physiology*; D000293:Adolescent; D000886:Anthropometry; D015519:Bone Density / Q000502:physiology*; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D006801:Humans; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology