Does Vitamin D add to the effect of 12‐weeks resistance training? A randomized controlled trial on healthy untrained young and elderly men

Abstract

IntroductionVitamin D (VitD) intake has shown to improve skeletal muscle function in VitD insufficient frail elderly. However, if VitD intake may improve the effect of resistance training (RT) in healthy individuals is unknown.Material and Methods20 healthy untrained young (age 22.8 ± 2.0) and 20 elderly (age 67.3 ± 4.3) men were randomized to 16 week daily supplementary intake of either 48 μg VitD + calcium (VitD‐group) or calcium (Placebo‐group), and underwent progressive RT of quadriceps muscle for the last 12 weeks. Pre and post 12 weeks RT cross sectional area (CSA), and isometric strength of quadriceps muscle was measured. Muscle fiber type morphology was analyzed from muscle biopsies taken pre and post training.ResultsVitD intake increased serum 25(OH)D levels in young and elderly to an extent that were different from the respective placebo group. RT increased CSA and isometric strength and improved skeletal muscle morphology of quadriceps muscle. However, no additive effect was seen from VitD intake in young or elderly.Conclusion12 weeks of RT altered CSA, strength and fiber type morphology of quadriceps muscle as expected. However, VitD intake did not add to the positive effect of RT.