Vitamin D deficiency associated with lower muscle elasticity in young adults

A cross-sectional study at Selcuk University Faculty of Medicine Hospital examined associations between serum 25-hydroxyvitamin D [25(OH)D], muscle elasticity, and physical function in 80 adults aged 18–45. Researchers compared 40 participants with 25(OH)D below 20 ng/mL with 40 whose levels were at least 20 ng/mL. Shear-wave elastography (SWE) measured elasticity in the flexor carpi radialis, short head of the biceps brachii, and tibialis anterior.

Elasticity measurements were lower in the deficient group across all three muscles (all p < 0.001), including analyses stratified by sex. Dominant- and non-dominant-hand fingertip pinch strength were also lower (p = 0.001 and p = 0.023, respectively). The groups were similar in demographic characteristics, physical activity, and SF-36 quality-of-life scores. Serum 25(OH)D correlated strongly with elasticity measurements (r = 0.870–0.916; p < 0.001). Areas under the receiver operating characteristic curve for distinguishing deficiency were 0.940, 0.957, and 0.935 for the three muscles, respectively.

The findings associate low vitamin D levels with altered muscle mechanical measurements and reduced pinch strength, without a corresponding difference in reported quality of life. The small, cross-sectional study cannot establish whether deficiency causes these changes or whether supplementation reverses them. Diagnostic performance was assessed within this young cohort; external validation would be needed before considering SWE for clinical identification of vitamin D deficiency.