title: Peripheral QCT sector analysis reveals early exercise-induced increases in tibial bone mineral density.
abstract: OBJECTIVE
  The purpose of this controlled trial was to determine whether subtle changes in mineralization and geometry of the tibia were evident following short term exercise interventions.
  
  
  METHODS
  Fifty-seven female volunteers (age 20.1±1.6) were randomized to one of four, 13-week training groups: sedentary control, resistance training, aerobic training, or combined aerobic-resistance. A pQCT image analysis software was developed and used to analyze images taken at sites 4%, 38% and 66% from the distal tibia at baseline and at completion of training. Parameters of bone mineral density, geometry and strength were determined for the entire scan cross-section and for each of six 60° polar sectors. Repeated-measures ANOVA and Fisher's LSD post hoc tests analyzed the effects of training over time.
  
  
  RESULTS
  Trabecular density (TrDn) at the 4% site increased from 279.8±37.1 to 283.1±36.0 mg/cm(3) in the aerobic group, and from 285.1±24.6 to 287.5±22.9 mg/cm(3) in the combined group over the study period (P≤0.001). Regional sector analyses revealed that impact exercises resulted in localized changes to the medial aspect of the tibia. Small increases in total bone area were observed in the diaphysis (38% site) (P<0.05).
  
  
  CONCLUSIONS
  Subtle, regional increases in trabecular density may be an early measurable manifestation of bone quality changes.
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, MA, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Evans
authors.forename: C H
authors.initials: CH
authors.lastname: Negus
authors.forename: A J
authors.initials: AJ
authors.lastname: Centi
authors.forename: B A
authors.initials: BA
authors.lastname: Spiering
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: B C
authors.initials: BC
authors.lastname: Nindl
mesh_terms: D015519:Bone Density / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D055815:Young Adult