Effect of Vitamin D Supplementation on Muscle Strength, Muscle Function, and Body Composition in Vitamin D-Deficient Middle-Aged Women.

: Sarcopenia is the loss of muscle strength and muscle mass with aging and is one of the major risk factors for metabolic diseases. Cross-sectional studies have shown that vitamin D is associated with sarcopenia in both men and women. We investigated the effect of vitamin D supplementation over 12 weeks on muscle strength, muscle function, and body composition in middle-aged women in randomized double-blind placebo-controlled trial format. This revealed a significant difference in serum 25-hydroxyvitamin D levels between the intervention and placebo groups. In addition, handgrip strength was improved, and the timed get up and go (TGUG) test and body fat content were decreased. This chapter presents a protocol for trial setup involving measurement of vitamin D levels, handgrip strength, the TGUT test, and body composition as readouts.