Young & Old: Vitamin D, Resistance Training & Skeletal Muscle

Research Paper Title

Does vitamin-D Intake during Resistance Training Improve the Skeletal Muscle Hypertrophic and Strength Response in Young and Elderly Men? – A Randomised Controlled Trial.

Introduction

Recent studies have shown that vitamin-D intake can improve skeletal muscle function and strength in frail vitamin-D insufficient individuals. The researchers investigated whether vitamin-D intake can improve the muscular response to resistance training in healthy young and elderly individuals, respectively.

Methods

Healthy untrained young (n = 20, age 20–30) and elderly (n = 20, age 60–75) men were randomised to 16 weeks of daily supplementary intake of either 48 μg of vitamin-D + 800 mg calcium (Vitamin-D-group) or 800 mg calcium (Placebo-group) during a period and at a latitude of low sunlight (December-April, 56°N). During the last 12 weeks of the supplementation the subjects underwent progressive resistance training of the quadriceps muscle. Muscle hypertrophy, measured as changes in cross sectional area (CSA), and isometric strength of the quadriceps were determined. Muscle biopsies were analysed for fiber type morphology changes and mRNA expression of vitamin-D receptor (VDR), cytochrome p450 27B1 (CYP27B1) and Myostatin.

Results

In the vitamin-D groups, serum 25(OH)D concentration increased significantly and at week 12 was significantly different from placebo in both young men (71.6 vs. 50.4 nmol/L, respectively) and elderly men (111.2 vs. 66.7 nmol/L, respectively). After 12 weeks of resistance training, quadriceps CSA and isometric strength increased compared to baseline in young (CSA p < 0.0001, strength p = 0.005) and elderly (CSA p = 0.001, strength p < 0.0001) with no difference between vitamin-D and placebo groups. Vitamin-D intake and resistance training increased strength/CSA in elderly compared to young (p = 0.008). In the young vitamin-D group, the change in fiber type IIa percentage was greater after 12 weeks training (p = 0.030) and Myostatin mRNA expression lower compared to the placebo group (p = 0.006). Neither resistance training nor vitamin-D intake changed VDR mRNA expression.

Conclusions

No additive effect of vitamin-D intake during 12 weeks of resistance training could be detected on either whole muscle hypertrophy or muscle strength, but improved muscle quality in elderly and fibre type morphology in young were observed, indicating an effect of vitamin-D on skeletal muscle remodelling.

Reference

Agergaard, J., Trostrupt, J., Uth, J., Iversen, J.V., Boesen, A., Andersen, J.L., Schjerling, P. & Langberg, H. (2015) Does vitamin-D Intake during Resistance Training Improve the Skeletal Muscle Hypertrophic and Strength Response in Young and Elderly Men? – A Randomized Controlled Trial. Nutrition and Metabolism. 12(32). DOI: 10.1186/s12986-015-0029-y.

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