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.
© 2021 John Wiley & Sons Ltd.