Associations between serum 25-hydroxyvitamin D 3 level and skeletal muscle mass and lower limb muscle strength in Japanese middle-aged subjects

One of the important risk factors of falling is decreased muscle mass and muscle strength. Recently, there has been an increasing concern on the role of vitamin D in muscle strength and physical activity. Aim of our study is to examine the relationships between vitamin D status and muscle mass and muscle strength in middle-aged healthy adults. Subjects were 40 healthy volunteers aged 42.0 ± 10.6 years old. Evaluation was made for serum vitamin D metabolites including 25-hydroxyvitamin D [25(OH)D ] and 24,25-dihydroxyvitamin D [24,25(OH) D ] concentrations, lower limb muscle strength, and dietary intake by food frequency questionnaire. Body composition was measured by dual-energy X-ray absorptiometry (DXA), and appendicular skeletal mass index (ASMI) was calculated as skeletal muscle mass/squared height. 70% of the subjects had vitamin D insufficiency/deficiency (serum total 25(OH)D