The interaction of aging with serum 25(OH)D and 1,25(OH)2 D status on muscle strength

Background To investigate the combination relationship of age with serum 25-hydroxyvitamin D (25(OH) D) and 1,25-(OH)2D3 levels on muscle strength. Methods We performed a cross-sectional study on 270 subjects containing 115 men and 155 women. Serum concentration of 25(OH) D and 1,25-(OH)2D3 were assessed. Hand grip strength (HGS) was measured using a digital dynamometer. Results There was no significant difference in mean of HGS among tertiles of 25(OH)D (P = .350) and 1,25(OH)(2) D (P = .467) before and after controlling for potential confounding factors. A significant difference in HGS was found between age categories in both crude (P < .001) and adjusted models (P = .018), where mean grip strength increased in the three first age categories, but decreased in the last group (48-69 years old). There was also a significant interaction between age and 25(OH) D (P = .049) and 1,25-(OH)2D3 (P = .047) on HGS, in which the combination effect increased the mean of muscle strength up to middle age after adjusting for confounders. Conclusions Serum 25(OH)D and 1,25(OH)(2) D were not related to muscle strength. However, age, and combination of age with both 25(OH)D and 1,25(OH)(2) D, significantly resulted in improving in muscle strength up to middle age.

Automated summary

The study investigated the combination relationship between age, serum 25-hydroxyvitamin D (25(OH) D), and 1,25-(OH)2D3 levels on muscle strength. Results showed that serum 25(OH)D and 1,25(OH)(2) D were not related to muscle strength, but age and the combination of age with these two types of vitamin D significantly improved muscle strength up to middle age.