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 is synthesised in the skin during exposure to sunlight and its fundamental roles are the regulation of calcium and phosphate metabolism and bone mineralisation. The aim of our study was to evaluate serum levels of 25-hydroxyvitamin D3, PTH and bone turnover markers (P1NP, OC, β-CTx, OC/β-CTx) and the intake of calcium and vitamin D in Polish Professional Football League (Ekstraklasa) players and in young men with a low level of physical activity. Fifty healthy men aged 19 to 34 years were included in the study. We showed that 25(OH)D3 and P1NP levels and OC/β-CTx were higher in the group of professional football players than in the group of physically inactive men. The daily vitamin D and calcium intake in the group of professional football players was also higher. We showed a significant relationship between 25(OH)D3 levels and body mass, body cell mass, total body water, fat-free mass, muscle mass, vitamin D and calcium intake. Optimum 25(OH)D3 levels were observed in a mere 16.7 % of the football players and vitamin D deficiency was observed in the physically inactive men. The level of physical activity, body composition, calcium and vitamin D intake and the duration of exposure to sunlight may significantly affect serum levels of 25(OH)D3.

Background. Antiplatelet therapy has become a standard therapeutic approach in the secondary prevention of cardiovascular system disorders of thrombotic origin. Patients with concomitant diabetes mellitus (DM) obtain fewer benefits from this treatment. Hence, the pathophysiology of altered platelet function in response to glucose metabolism impairment should be of particular interest. Objectives. The aim of our study was to verify if the platelet expression of the asymmetric dimethylarginine (ADMA) in diabetic patients differs in comparison to the nondiabetic ones. The correlation of platelet-ADMA with platelet activation and aggregation as well as with other risk factors was also investigated. Material and Methods. A total of 61 subjects were enrolled in this study, including thirty-one type 2 diabetic subjects without diabetes-related organ damage. Physical examination was followed by blood collection with an assessment of platelet aggregation, traditional biochemical cardiovascular risk factors, and evaluation of nitric oxide bioavailability parameters in plasma and thrombocytes. Subsequently, the assessment of endothelial function using Peripheral Arterial Tonometry and Laser Doppler Flowmetry (LDF) was performed. Results. In the DM group, elevated concentration of intraplatelet ADMA and higher ADMA/SDMA ratio compared to the control group was observed. It was accompanied by higher ADP-mediated platelet aggregation and lower microvascular response to a local thermal stimulus measured by LDF in the diabetes group. Conclusions. Type 2 diabetes is related to higher intraplatelet concentration of asymmetric dimethylarginine (ADMA), which may result in impaired platelet-derived nitric oxide synthesis and subsequent increased platelet activity, as assessed by the ADP-induced aggregation. Laser Doppler Flowmetry, compared to EndoPAT 2000, appears to be a more sensitive indicator of the impaired microvasculature vasodilation in diabetics without the presence of clinically significant target organ damage.