Odd-impact loading results in increased cortical area and moments of inertia in collegiate athletes

Abstract

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. 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). 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. 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.