Article

Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: Implications for skeletal muscle function

a Muscle Metabolism and Physiology Research group, Research Institute for Sport and Exercise Sciences , Liverpool John Moores University , Liverpool , UK.
Journal of Sports Sciences (Impact Factor: 2.1). 10/2012; 31(4). DOI: 10.1080/02640414.2012.733822
Source: PubMed

ABSTRACT Abstract The current study implemented a two-part design to (1) assess the vitamin D concentration of a large cohort of non-vitamin D supplemented UK-based athletes and 30 age-matched healthy non-athletes and (2) to examine the effects of 5000 IU · day(-1) vitamin D(3) supplementation for 8-weeks on musculoskeletal performance in a placebo controlled trial. Vitamin D concentration was determined as severely deficient if serum 25(OH)D < 12.5 nmol · l(-1), deficient 12.5-30 nmol · l(-1) and inadequate 30-50 nmol · l(-1). We demonstrate that 62% of the athletes (38/61) and 73% of the controls (22/30) exhibited serum total 25(OH)D < 50 nmol · l(-1). Additionally, vitamin D supplementation increased serum total 25(OH)D from baseline (mean ± SD = 29 ± 25 to 103 ± 25 nmol · l(-1), P = 0.0028), whereas the placebo showed no significant change (53 ± 29 to 74 ± 24 nmol · l(-1), P = 0.12). There was a significant increase in 10 m sprint times (P = 0.008) and vertical-jump (P = 0.008) in the vitamin D group whereas the placebo showed no change (P = 0.587 and P = 0.204 respectively). The current data supports previous findings that athletes living at Northerly latitudes (UK = 53° N) exhibit inadequate vitamin D concentrations (<50 nmol · l(-1)). Additionally the data suggests that inadequate vitamin D concentration is detrimental to musculoskeletal performance in athletes. Future studies using larger athletic groups are now warranted.

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    • " - ing seasonal changes and time from last effective ultraviolet exposure . Several other studies that assessed the plasma 25 ( OH ) D concentrations of UK - based athletes have shown that there was no change or a significant decrease in the plasma 25 ( OH ) D levels during the winter training period in athletes without vitamin D supplementation ( Close et al . , 2013 ; He et al . , 2013 ; Owens et al . , 2014 ) . This is most likely due to insufficient ultraviolet radiation of appropriate wavelength ( 290 – 315 nm ) between November and March in the UK to produce vitamin D in the skin ( Webb & Holick , 1988 ) ."
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    ABSTRACT: Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D3 supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D3 supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D3 group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D3 group was higher than in the placebo group (P = 0.025). Only in the vitamin D3 group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D3 supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.
    Journal of Sports Sciences 04/2015; DOI:10.1080/02640414.2015.1033642 · 2.10 Impact Factor
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    • "Our observations are comparable to several studies showing that vitamin D is linearly associated with jumping ability and strength in pre-adolescent girls [2] and elderly individuals [7], [12], [27], and in agreement with the observation that 100 m performance was enhanced after a single biodose of ultraviolet radiation in collegiate women [28]. Moreover, a recent vitamin D supplementation-study on professional soccer players revealed that inadequate vitamin D concentration was detrimental to jumping and sprinting ability, whereas supplementation counteracted this effect [29]. Notably, regarding muscular strength, Hamilton et al. [9] reported that vitamin D levels were not associated with lower limb isokinetic muscle function in soccer players. "
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    ABSTRACT: Aim The current study had two aims. The primary purpose was to examine the association between serum vitamin D levels and the ergometric evaluation of muscle strength, aerobic capacity, and speed in professional soccer players. The secondary aim was to evaluate the effects of the soccer off-season period on serum vitamin D levels. Methods Sixty-seven Caucasian male soccer players (age 25.6±6.2 and height 1.81±0.08 m), members of two Greek Superleague Soccer teams and one Football-league championship team participated in this study. Exercise performance testing for the determination of squat jump (SJ), countermovement jump (CMJ), 10 (10 m) and 20 meters (20 m) sprint performance, maximal oxygen consumption (VO2max), anthropometry, and blood sampling were performed before (pre) and after (post) the six-week off-season period. Results Analysis of our results showed the following: (a) a significant correlations between serum vitamin D levels and performance parameters in both pre (SJ; P<0.001, CMJ; P<0.001, VO2max; P<0.001, 10 m; P<0.001, and 20 m; P<0.001) and post (SJ; P<0.001, CMJ; P<0.001, VO2max; P = 0.006, 10 m; P<0.001, and 20 m; P<0.001) experimental sessions. (b) Vitamin D concentration increased significantly (P<0.001) following the six-week off-season period compared to baseline, while at the same time all measured performance parameters decreased (SJ; P<0.001, CMJ; P<0.001, 10 m; P<0.001, 20 m; P<0.001, VO2max; P<0.001). Discussion Our findings suggest that vitamin D levels are associated with the ergometric evaluation of muscle strength, as expressed by SJ and CMJ, sprinting capacity, and VO2max in professional soccer players, irrespective the levels of performance. Furthermore, our data reaffirm the importance of UVB on serum vitamin D levels. Moreover, reductions in exercise training stress may also have beneficial effects on vitamin D levels, suggesting a possible association of its levels and the training-induced stress. Our results indicate a possibly bidirectional interaction between soccer performance indices and vitamin D levels.
    PLoS ONE 07/2014; 9(7):e101659. DOI:10.1371/journal.pone.0101659 · 3.23 Impact Factor
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    • "Therefore, the plasma concentration of 25(OH)D is considered to be the primary indicator of vitamin D status [1]. Plasma 25(OH)D values commonly accepted as the reference range [2] are as follows. In healthy humans, 25(OH)D > 100 nmol/L are defined as optimal vitamin D status and levels from 50 to 100 nmol/L are defined as adequate. "
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    ABSTRACT: Aim. Our aims were to determine the influence of plasma total 25-hydroxy vitamin D (25(OH)D) status on the plasma cytokine concentrations in athletes and the in vitro effects of different doses of 1, 25 dihydroxyvitamin D3 (1, 25(OH)2D3) on multiantigen stimulated cytokine production by whole blood and peripheral blood mononuclear cell (PBMC) cultures. Methods. Plasma samples from 43 athletes with high and low levels of 25(OH)D were assayed for the concentrations of cytokines. The whole blood samples and PBMCs from healthy subjects were incubated in vitro with a multi-antigen vaccine and different doses of added 1, 25(OH)2D3. The circulating cytokines and stimulated whole blood and PBMC culture production of cytokines were determined using a biochip assay. Results. The circulating interleukin-(IL-)10 and interferon-(IFN-) γ concentrations were significantly higher in the vitamin D sufficient athletes. Furthermore, the production of tumour necrosis factor-(TNF-) α, IL-6, IFN-γ, IL-2, and IL-10 by whole blood culture was significantly inhibited by 1, 25(OH)2D3 concentrations of 1000 pmol/L or 10000 pmol/L. Conclusions. We found that the influence of vitamin D on circulating cytokines might be different in athletes compared with nonathletes and cytokines production by whole blood culture was not influenced by 1, 25(OH)2D3 in concentrations within the normal healthy range.
    01/2014; 2014. DOI:10.1155/2014/820524
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