Vitamin D status is associated with muscular strength in a nationally representative sample of US youth.

AIM: To evaluate the association between serum 25-hydroxyvitamin D (25OHD) and muscular strength in a nationally representative sample of US youth. METHODS: Participants (n = 3350) were 6- to 18-y-olds from 2011 to 2014 National Health and Nutrition Examination Survey. Relative handgrip strength was quantified using age- and sex-specific z-scores. Poor strength was defined as those <25th percentile. Multivariate general linear and logistic models were used to compare strength and poor strength status by clinically relevant groupings of 25OHD. RESULTS: Approximately 20.2% of youth had 25OHD <50 nmol/L. Mean relative strength was highest for those at ≥75 nmol/L of 25OHD. The percentage of boys/girls with poor strength in the <50 nmol/L, 50-74.9 nmol/L and ≥75 nmol/L groups was 34.9%/32.3%, 25.8%/28.2% and 14.0%/15.8%, respectively. The odds of boys and girls with <50 nmol/L 25OHD having poor strength were 2.8 (95% CI: 1.4, 5.5) and 3.4 (1.7, 6.8) times higher compared to those with ≥75 nmol/L, respectively. CONCLUSION: Higher levels of circulating vitamin D were associated with higher relative strength, and poor strength was more prevalent when 25OHD was <75 nmol/L. These findings highlight the value of vitamin D for the muscle-bone unit and potential extraskeletal ramifications.