04 BINKLEY.pdf

This study investigates muscle-bone relationships in the lower leg of healthy pre-pubertal children, focusing on four muscle measures as predictors of tibia bone strength. The research aims to:

1. Establish Correlations: Determine if muscle size and mass (cross-sectional muscle area (CSMA) and leg lean mass (LLM)) have stronger correlations with bone strength (polar strength strain index (pSSI)) than measures of muscle strength (power and force).
2. Compare Partial-R Values: Assess that models controlling for age, sex, height, and weight will yield higher partial-R values for CSMA and LLM in predicting pSSI compared to power and force.
3. Assess Bone Density: Confirm that muscle predictors are associated with bone size but not with volumetric bone mineral density (vBMD) at the 20% distal tibia site.

The study involved 105 pre-pubertal children (54 males), aged 7-16 years, recruited from a community and an elementary school. Measures included pQCT for CSMA and pSSI, DXA for LLM, and ground reaction force analysis for power and force during a two-footed jump.

Key Findings:

- Muscle Size and Mass Predicted Bone Strength: Both CSMA and LLM showed strong correlations with pSSI (R=0.84 to 0.92), while power and force had weaker associations (R=0.66).
- Partial-R Values: Models controlling for other factors revealed higher partial-R values for LLM (0.21) followed by CSMA (0.14-0.15) and power (0.04) in predicting pSSI.
- Bone Size vs. Density: Muscle predictors were significantly associated with total and cortical area but not with vBMD at the 20% distal tibia site.

These findings support the importance of muscle size and mass as predictors of bone strength in growing children, emphasizing the role of muscle-bone relationships in understanding bone health during periods of rapid growth.