Bone strength index in adolescent girls: does physical activity make a difference?

Area of Science:

• Orthopedics
• Sports Medicine
• Biomedical Engineering

Background:

• Bone strength index (BSI) integrates bone mineral and biomechanical properties for a comprehensive measure of bone resistance to bending.
• BSI may offer greater clinical significance for fracture risk assessment compared to bone mineral content (BMC) or areal density alone.
• BSI is calculated using dual-energy x-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) for non-invasive in vivo assessment.

Purpose of the Study:

• To compare BSI in adolescent female middle-distance runners versus age-matched controls.
• To identify factors that predict BSI in adolescent girls.

Main Methods:

• Twenty middle-distance runners and 20 controls (mean age 16 years) were recruited.
• BSI was calculated using DXA-derived BMC and MRI-assessed bone geometry and biomechanical properties in a 10% mid-distal tibia region.
• Predictive factors for BSI were also analyzed.

Main Results:

• Athletes exhibited significantly higher BMC, cortical bone volume, volumetric cortical BMD, cross-sectional moments of inertia, and BSI in the distal tibia compared to controls.
• Weekly hours of physical activity emerged as the strongest predictor of BSI (R² = 0.46).

Conclusions:

• Adolescent female athletes with high training loads demonstrated a greater BSI at the distal tibia.
• BSI is confirmed as a significant and discerning marker for musculoskeletal health in adolescent girls across varying physical activity levels.