An Evaluation of the Levels of Vitamin D and Bone Turnover Markers After the Summer and Winter Periods in Polish Professional Soccer Players

Abstract

Vitamin D is synthesised in the skin during exposure to sunlight. The fundamental roles of vitamin D are the regulation of calcium and phosphate metabolism and bone mineralisation. Low vitamin D levels in athletes may adversely affect their exercise capabilities. The aim of our study was to investigate changes in serum levels of 25(OH)D3, calcium and bone turnover markers in football players in two training periods differing in the exposure to sunlight (after the summer period and after the winter period). We investigated 24 Polish professional soccer players. Serum levels of the following parameters were determined: 25(OH)D3, calcium, osteocalcin (OC), parathormone (PTH), procollagen type I N - terminal peptide (P1NP), and beta - CrossLaps (beta - CTx). We showed significantly higher levels of 25(OH)D3 and calcium and lower levels of PTH after the summer period versus the winter period. No significant differences in the levels of bone turnover markers were found. Furthermore, we did not observe any significant correlations between the levels of 25(OH)D3 and other parameters. Normal levels of 25(OH)D3 were observed in 50% of the players after the summer period and only in 16.7% of the players after the winter period. It is justified to measure the levels of 25(OH)D3, calcium and PTH in soccer players, especially after the winter period, when the exposure to sunlight is limited.

Vitamin D and Exercise Performance in Professional Soccer Players

“…This finding was unanticipated by the authors since they expected vitamin D levels to increase or at least to remain constant due to the adequate daily exposure to UVB during the whole study. Further support is coming from two recent studies on soccer players [43], [48]. The authors observed much lower vitamin D levels (30,82±9,04 [42], 32,83±6,64 [48]) and insufficiency values (83% <30 ng/ml [42], 65% <30 ng/ml [48]) during periods of training, compared to the ones we obtained after the six-week detraining period (45,67±13,70; 4,47<30 ng/ml).…”

Vitamin D and Physical Activity

“…Similar variations have been reported for athletes. In soccer players, the levels of 25(OH)D3 are normal in 50 % of the athletes, while this number drops to 16.7 % in winter [32]. A study performed in a high latitude (Laramie, WY 41.3°N) revealed vitamin D insufficiency of 63 % in winter compared to only 12 % in autumn and 20 % in spring in both indoor and outdoor athletes [38].…”

“…Koundourakis et al [28] showed that professional Greek soccer players' training at a latitude of 35.9°N had insufficient vitamin D levels, while nearly identical levels were reported in American national football league players [29], in elite gymnasts in Australia [30], and in young Hawaiian skateboarders [31] and a variety of other athletes worldwide [32][33][34][35]. These findings were observed irrespective of sun exposure.…”

Muscular effects of vitamin D in young athletes and non-athletes and in the elderly

“…In soccer players, the levels of serum vitamin D are "normal" in 50% of athletes during summer, whereas it drops to 16% in winter. 105 A study performed in a high latitude area (Laramie, WY 41.3°N) revealed that the prevalence of "low" vitamin D was about 63% in winter compared to only 12% in autumn and 20% in spring in both indoor and outdoor athletes. 104 Similar findings have been reported in a study conducted at higher latitudes (Ellensburg, WA 46.9°N) using exclusively outdoor athletes.…”