The effects of a vitamin D randomised controlled trial on muscle strength and power in female adolescent athletes : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Human Nutrition at Massey University, Albany, New Zealand
Year: 2013
Type: dissertation
Study designs: Randomized Controlled Trial, Clinical Trial
Abstract: Background: \n \n \nVitamin D deficiency is widespread in the general public and emerging evidence has revealed it is \ncommon in athletic populations, particularly those who train indoors. Recent studies suggest that \nvitamin D deficiency is correlated with impaired skeletal muscle function; however there is limited \nevidence from randomised controlled trials that vitamin D supplementation can improve muscle \nstrength and power in trained athletes. \n \nObjective: \n \n \nTo investigate the effects of vitamin D3 supplementation on serum 25(OH)D concentrations and muscle \nstrength and power in female adolescent athletes training predominantly indoors. \n \nMethods: \n \n \nFemale adolescent dancers, gymnasts, and swimmers (n = 61) who trained regularly for at least five \nhours per week participated in this randomised double blind placebo controlled trial. Participants \nwere stratified to receive 50,000 IU vitamin D3 or placebo every month for six months. Serum \n25(OH)D concentrations, muscle strength (handgrip and isokinetic knee extensor and flexor torque), \npower (vertical jump), and anthropometric measurements were assessed at baseline and endpoint (n = \n54). \n \nResults: \n \nAt baseline, the median 25(OH)D concentration was 77.5 [63.5,92] nmol/L for the vitamin D group \nand 74 [64.5,88.5] nmol/L for the placebo group. Following six months of supplementation, serum 25(OH)D concentrations increased significantly in the vitamin D \ngroup (16.5 [7,46] nmol/L) (P = 0.001), but not the placebo group (-6.25 [-21,44] nmol/L). Peak \ntorque (Nm) of the knee extensors in concentric and eccentric extension increased significantly for \nboth groups (P <0.05), and there was no significant difference in change in peak torque between \ngroups. After controlling for change in \n25(OH)D and baseline 25(OH)D separately, supplementation with vitamin D was not associated with any \nof the strength or power variables. \n \nConclusions: \n \n \nSupplementation of 50,000 IU of vitamin D3 per month improved vitamin D status but did not improve \nthe chosen measures of muscle strength and power in this group of female adolescent athletes. This \nmay be due in part to the small sample size and high baseline serum 25(OH)D concentrations seen in \nthis cohort. \n \nKeywords: skeletal muscle strength, skeletal muscle power, athletes, dancers, gymnasts, vitamin D, \n25(OH)D
Author: Sarah Mitchell
Language: English
Topic: Vitamin D Research Studies
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2258206894