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Abstract
While optimal vitamin D nutriture and muscle development in children are both important for long-term bone health, little is known about the relationship between vitamin D and muscle in the pediatric setting. The objective was to determine the relationships between serum 25(OH)D concentrations and select muscle parameters [i.e., tibia and radius muscle cross-sectional area (MCSA) and density by peripheral quantitative computed tomography, forearm strength by handgrip dynamometry, and total body fat-free soft tissue (FFST) by dual energy X-ray absorptiometry] in early pubertal children and if race and sex modify these relationships. Serum 25(OH)D concentrations were measured using radioimmunoassay. Black (n = 21) and white (n = 40) males (aged 10 to 13 years) and black (n = 25) and white (n = 40) females (aged 9 to 12 years) living at 34N latitude in the U.S. participated in this study. No significant relationships were found between serum 25(OH)D concentrations and MCSA, muscle density, forearm strength or FFST. Serum 25(OH)D was negatively associated with parathyroid hormone (p = 0.001). PTH was significantly related to arm MCSA, leg MCSA, and FFST (r > 0.206; p < 0.033). This cross-sectional study did not support a relationship between vitamin D and muscle parameters in a sample of early pubertal children, regardless of sex and race. It may be that PTH is a more relevant marker of muscle function than 25(OH)D in early pubertal children. Vitamin D intervention trials will help elucidate these relationships more clearly.