title: Odd-impact loading results in increased cortical area and moments of inertia in collegiate athletes.
abstract: OBJECTIVE
  The purpose of this study was to investigate tibial changes in volumetric bone mineral density and geometry that take place in athletes from pre- to post-season.
  
  
  METHODS
  Female college athletes (n = 36) and ten controls recruited from the student population were included in the study. Participants had their left tibia scanned by pQCT at 4, 20, and 66 % of the overall length from the distal end before and after their competitive seasons. Subjects were divided into four groups: non-athlete (controls, n = 10), moderate-impact (cross-country runners, n = 13), high-impact (volleyball and basketball, n = 11), and odd-impact (soccer, n = 12).
  
  
  RESULTS
  Anterior-posterior and medial-lateral diameter increased at the 4 % site in control subjects. In the moderate-impact group, medial-lateral moment of inertia (MOI) increased by 1.2 ± 1.8 (mean ± SD) percent at the 20 % site. In high-impact group, anterior-posterior MOI increased by 1.6 ± 2.0 percent at the 66 % site. In odd-impact group, cortical area (1.4 ± 2.3 %) and cortical thickness (1.8 ± 2.8 %) increased at the 20 % site increased, as did the polar MOI (1.8 ± 2.2 %) at the 66 % site.
  
  
  CONCLUSIONS
  Load-specific changes resulting in improved measures of bone strength take place in athletes during a competitive season. These changes may result in improved resistance to fractures and stress fractures.
authors.affiliation: Ethel Austin Martin Program in Human Nutrition, South Dakota State University, Box 506, Brookings, SD, 57007, USA, Lee.Weidauer@sdstate.edu.
authors.forename: Lee
authors.initials: L
authors.lastname: Weidauer
authors.forename: Maggie
authors.initials: M
authors.lastname: Minett
authors.forename: Charles
authors.initials: C
authors.lastname: Negus
authors.forename: Teresa
authors.initials: T
authors.lastname: Binkley
authors.forename: Matt
authors.initials: M
authors.lastname: Vukovich
authors.forename: Howard
authors.initials: H
authors.lastname: Wey
authors.forename: Bonny
authors.initials: B
authors.lastname: Specker
mesh_terms: D000222:Adaptation, Physiological; D056352:Athletes; D001696:Biomechanical Phenomena; D015519:Bone Density; D016022:Case-Control Studies; D003163:Competitive Behavior; D005260:Female; D006801:Humans; D013334:Students; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing