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Regina M. Lewis, Maja Redzic, and D. Travis Thomas

The purpose of this 6-month randomized, placebo-controlled trial was to determine the effect of season-long (September–March) vitamin D supplementation on changes in vitamin D status, which is measured as 25(OH) D, body composition, inflammation, and frequency of illness and injury. Forty-five male and female athletes were randomized to 4,000 IU vitamin D (n = 23) or placebo (n = 22). Bone turnover markers (NTx and BSAP), 25(OH)D, and inflammatory cytokines (TNF-alpha, IL-6, and IL1-β) were measured at baseline, midpoint, and endpoint. Body composition was assessed by DXA and injury and illness data were collected. All athletes had sufficient 25(OH)D (> 32 ng/ml) at baseline (mean: 57 ng/ml). At midpoint and endpoint, 13% and 16% of the total sample had 25(OH)D < 32 ng/ml, respectively. 25(OH)D was not positively correlated with bone mineral density (BMD) in the total body, proximal dual femur, or lumbar spine. In men, total body (p = .04) and trunk (p = .04) mineral-free lean mass (MFL) were positively correlated with 25(OH)D. In women, right femoral neck BMD (p = .02) was positively correlated with 25(OH)D. 25(OH)D did not correlate with changes in bone turnover markers or inflammatory cytokines. Illness (n = 1) and injury (n = 13) were not related to 25(OH)D; however, 77% of injuries coincided with decreases in 25(OH)D. Our data suggests that 4,000 IU vitamin D supplementation is an inexpensive intervention that effectively increased 25(OH)D, which was positively correlated to bone measures in the proximal dual femur and MFL. Future studies with larger sample sizes and improved supplement compliance are needed to expand our understanding of the effects of vitamin D supplementation in athletes.

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Nicholas B. Tiller

authors assessed cardiorespiratory fitness before and after the trial, reporting an increase in absolute V ˙ O 2 max from 2.0 to 2.6 L/min ( p  < .001) in the vitamin D-supplemented group, with no change in controls. This equates to an increase in V ˙ O 2 max of ∼28% relative to baseline. According to

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Kelly Pritchett, Robert C. Pritchett, Lauren Stark, Elizabeth Broad, and Melissa LaCroix

or those participating in sports that require uniforms that minimize skin exposure ( Constantini et al., 2010 ). Given the strong evidence suggesting that vitamin D levels may be lower for certain sports during the winter months, recent research has examined the effects of vitamin D supplementation

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Leslie N. Silk, David A. Greene, and Michael K. Baker

Research examining the preventative effects of calcium and vitamin D supplementation has focused on children and females, leaving the effects on male bone mineral density (BMD) largely unexplored. Thus, the aim of this systematic review and meta-analysis is to examine the efficacy of calcium supplementation, with or without vitamin D for improving BMD in healthy males. Medline, EMBASE, SPORTDiscus, Academic Search Complete, CINHAHL Plus and PubMed databases were searched for studies including healthy males which provided participants calcium supplementation with or without vitamin D and used changes to BMD as the primary outcome measure. Between trial standardized mean differences of percentage change from baseline in BMD of femoral neck, lumbar spine, total body and total hip sites were calculated. Nine studies were included in the systematic review with six references totaling 867 participants contributing to the meta-analysis. Significant pooled effects size (ES) for comparison between supplementation and control groups were found at all sites included in the meta-analysis. The largest effect was found in total body (ES = 0.644; 95% CI = 0.406–0.883; p < .001), followed by total hip (ES = 0.483, 95% CI= 0.255–0.711, p < .001), femoral neck (ES = 0.402, 95% CI = 0.233–0.570, p = .000) and lumbar spine (ES = 0.306, 95% CI = 0.173–0.440, p < .001). Limited evidence appears to support the use of calcium and vitamin D supplementation for improving BMD in older males. There is a need for high quality randomized controlled trials, especially in younger and middle-aged male cohorts and athletic populations to determine whether supplementation provides a preventative benefit.

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Hyun Chul Jung, Myong Won Seo, Sukho Lee, Sung Woo Jung, and Jong Kook Song

and function ( Barker et al., 2013 ), increased rates of stress fractures ( Ruohola et al., 2006 ), and even poor athletic performance ( Koundourakis et al., 2014 ). Vitamin D supplementation has been proposed for facilitating the number of processes that are important for optimal physical performance

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Gal Dubnov-Raz, Netachen Livne, Raanan Raz, Avner H. Cohen, and Naama W. Constantini

It is hypothesized that vitamin D insufficiency in athletes might negatively affect sport performance. The objective of this study was to examine the effect of vitamin D3 supplementation on physical performance of adolescent swimmers with vitamin D insufficiency. Fifty-three adolescent competitive swimmers with vitamin D insufficiency (serum 25-hydroxyvitamin-D concentrations (25(OH)D)<30ng/ml, mean 24.2 ± 4.8ng/ml) were randomized to receive 2,000IU/day of vitamin D3 or placebo for 12 weeks. Swimming performance at several speeds, arm-grip strength, and one-legged balance, were measured before and after supplementation. The age-adjusted changes in performance variables during the study were compared between groups. 25(OH) D concentrations at study end were significantly higher in the vitamin group compared with the placebo group (29.6 ± 6.5ng/ml vs. 20.3 ± 4.2ng/ml, p < .001), yet only 48% of the vitamin group became vitamin D sufficient with this dosing. No between-group differences were found in the changes of the performance variables tested. No significant differences in performance were found between participants that became vitamin D sufficient, and those who did not. No significant correlation was found between the change in serum 25(OH)D and ageadjusted balance, strength or swimming performance at study end. Vitamin D3 supplementation that raised serum 25(OH)D concentrations by a mean of 9.3ng/ml above placebo in adolescent swimmers with vitamin D insufficiency, did not improve physical performance more than placebo.

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Gal Dubnov-Raz, Harri Hemilä, Avner H. Cohen, Barak Rinat, Lauryn Choleva, and Naama W. Constantini

Observational studies identified associations between vitamin D insufficiency (serum 25(OH)D > 30ng·ml−1) and risk of upper respiratory infection (URI). Swimmers are highly prone to URIs, which might hinder their performance. The aim of this study was to examine if vitamin D3 supplementation reduces URI burden in vitamin D-insufficient swimmers. Fifty-five competitive adolescent swimmers with vitamin D insufficiency were randomized to receive vitamin D3 (2,000IU·d4) or placebo for 12 winter weeks. A URI symptom questionnaire was completed weekly. Serum 25(OH)D concentrations were measured by radio-immunoassay before and after supplementation. We used linear regression to examine the relation between the change in 25(OH)D concentrations during the trial, and the duration and severity of URIs. There were no between-group differences in the frequency, severity, or duration of URIs. Exploratory analyses revealed that in the placebo group only, the change in 25(OH)D concentrations during the trial was highly associated with the duration of URIs (r = −0.90,p > .001), and moderately associated with the severity of URIs (r = −0.65,p = .043). The between-group differences for duration were highly significant. Vitamin D3 supplementation in adolescent swimmers with vitamin D insufficiency did not reduce URI burden. However, larger decreases in serum 25(OH)D concentrations were associated with significantly longer and more severe URI episodes.

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Jeane Franco Pires Medeiros, Michelle Vasconcelos de Oliveira Borges, Aline Alves Soares, Elys Costa de Sousa, José Ronaldo Ribeiro da Costa, Weberthon Alessanderson Costa Silva, Magnus Vinícius Bezerra de Sousa, Vivian Nogueira Silbiger, Paulo Moreira Silva Dantas, and André Ducati Luchessi

This article has been retracted as of May 6, 2022, because concerns were received from a reader that the article contains inaccurate data. An independent review of the study data was conducted in coordination with the authors, and it was determined that the originally published data are inaccurate and a complete set of corrected data is not available as the authors claim a portion of the original measurements have been lost. As a result of these findings, the article is retracted.

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Kirsty A. Fairbairn, Ingrid J.M. Ceelen, C. Murray Skeaff, Claire M. Cameron, and Tracy L. Perry

people with serum 25-hydroxyvitamin D (25(OH)D) concentrations below 50 nmol/L improves muscle strength, power, and performance ( Glerup et al., 2000 ; Gupta et al., 2010 ). A meta-analysis of nonathletic participants with low vitamin D status reported that vitamin D supplementation improved muscle

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Matthew A. Wyon, Roger Wolman, Nicolas Kolokythas, Karen Sheriff, Shaun Galloway, and Adam Mattiussi

48%). 6 Low serum 25(OH)D has been linked to reduced muscle strength and power which are fundamental to athletic performance 6 , 7 ; this has further been associated with an increased incidence of injury. 8 , 9 Vitamin D supplementation has become recommended practice in a number of sports including