Association of Vitamin D Supplementation in Cardiorespiratory Fitness and Muscle Strength in Adult Twins: A Randomized Controlled Trial

Abstract

Background: Although vitamin D is related to cardiorespiratory fitness and muscle strength, there is no evidence in the literature about the genetic influence of the response to the increase in body vitamin D. Therefore, we evaluate the effect of longitudinal supplementation of vitamin D on parameters of physical fitness in monozygotic twins.Methods: In total, 74 participants were included, with a mean age of 25 years, divided into two groups, one group received supplementation with cholecalciferol for 60 days and the other group did not. Cardiorespiratory fitness and muscle strength were measured before and after supplementation, through maximal treadmill tests and dynamometry, respectively. Wilcoxon tests were used to compare intra-group results and the Mann-Whitney test to examine intergroup differences.Results: There was an increase in the serum concentration of vitamin D in participants who ingested the supplementation. Cardiorespiratory fitness improved after supplementation through increases in the values of maximum oxygen consumption of 28% (P <0.001). Muscle strength in right hand grip significantly increased in participants who received the supplement to 33.0 (P = 0.007).Conclusion: 60 days of cholecalciferol supplementation improved cardiorespiratory fitness and upper limb muscle strength.Trial registration: RBR-3qy2f2. Registered 28 March 2016, http://www.ensaiosclinicos.gov.br/rg/RBR-3qy2f2/2