The association between 25-hydroxyvitamin D levels and muscle strength in adolescents.

Abstract

Background: since the discovery of the vitamin D receptor in muscle cells, relatively few studies conducted in adolescents have reported with conflicting results the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and muscle strength. Methods: the National Health and Nutrition Examination Survey during the period 2011-2014 was analyzed to examine the association between vitamin D status and the combined maximum grip strength, as a proxy for overall muscle strength in participants aged 10 to 19 years. According to the American Endocrine Society guidelines, subjects with 25(OH)D levels < 20 ng/mL, 20 to 30 ng/mL, and > 30 ng/mL were defined as having deficient, insufficient, and sufficient vitamin D, respectively. General linear models were assembled to examine this association. Results: of 2,528 participants with a mean age of 14.5 years, the prevalence of vitamin D deficiency and sufficiency was 25.6 % and 25.9 %, respectively. As expected, maximum grip strength increased with age and was stronger in boys than that in girls. Notably, after adjusting for potential confounders, boys and girls with vitamin D sufficiency were on average 2.9 kg and 2.1 kg stronger than their counterparts with vitamin D deficiency, respectively. Moreover, boys defined as having severe vitamin D deficiency (< 12 ng/mL) were 4.1 kg weaker than those who did not. Conclusion: in adolescents, vitamin D sufficiency was significantly associated with stronger combined maximum grip strength. The present findings should be further investigated to determine if maintaining optimal 25(OH)D concentrations might result in greater muscle strength in adolescents.