## 3 Results  
Table 1 summarises the age, body composition, and vitamin D levels of the 21 athletes finally included in the study of players distinguished by playing position. Despite the different physical demands of the different playing positions in the sport of football, no significant differences were observed in any anthropometric variable or vitamin D levels or in the age of the players according to their playing position. \begin{table}
\begin{tabular}{l c c c c c c} \hline  & **Total (n = 21)** & **Goalkeeper** & **Defender** & **Midfielder** & **Forward** & **[PERSON]–** \\  & **(n = 2)** & **(n = 6)** & **(n = 8)** & **(n = 5)** & **[PERSON] Test** \\  & **M (Min–Max, IQR)** & **M** & **M** & **M** & **M** \\  & **(Min–Max)** & **(Min–Max)** & **(Min–Max)** & **(Min–Max)** & **H** & **\(p\)** \\ \hline Age & 24 & 24.50 & 21–28 & 24.50 & 25.00 & 25.00 & \\  & (20–33, 4) & 24.50 & 21.00–29.00 & 22 (20–30) & 23.00–33.00 & 3.909 & 0.271 \\ Weight (kg) & 62.00 & 69.80 & 65.05 & 56.65 & 60.80 & \\  & (53.70–80.60, 12.00) & (62.00–77.60) & (56.30–70.30) & (53.70–74.50) & (54.20–80.60) & 4.292 & 0.232 \\ Height (m) & 1.67 & 1.69 & 1.69 & 1.64 & 1.69 & 2.674 & 0.445 \\  & (1.55–1.81, 0.10) & (1.63–1.74) & (1.64–1.75) & (1.55–1.81) & (1.64–1.79) & \\  & 22.37 & 24.48 & 22.43 & 21.54 & 22.06 & \\ BMI (kg/m\({}^{2}\)) & (18.98–25.63, 1.92) & (23.34–25.63) & (20.93–24.91) & (20.21–22.81) & (18.98–25.16) & 5.324 & 0.150 \\ \% Fat Mass Carter & 16.32 & 21.42 & 16.38 & 16.81 & 15.03 & \\  & (12.87–26.14, 4.71) & (21.03–21.81) & (12.87–18.63) & (13.86–26.14) & (13.71–16.82) & 6.345 & 0.096 \\ FFM (kg) & 51.18 & 54.82 & 54.05 & 47.37 & 52.01 & \\  & (44.24–68.48, 8.62) & (48.96–60.68) & (49.06–60.75) & (44.24–55.03) & (46.77–68.48) & 6.614 & 0.085 \\ FM (kg) & 10.46 & 14.98 & 10.60 & 9.81 & 9.25 & 4.349 & 0.226 \\  & (7.24–19.47, 2.74) & (13.04–16.92) & (7.24–11.72) & (7.46–19.47) & (7.43–12.12) & \\ Vitamin D (ng/mL) & 35.80 & 35.75 & 31.65 & 34.80 & 39.50 & \\  & (18.70–63.80, 13.85) & (24.80–46.70) & (23.40–37.50) & (18.70–45.80) & (22.60–63.80) & 1.145 & 0.766 \\ \hline \end{tabular}
\end{table} 
Table 1: Sample characteristics and differences by playing position. Figure 1 illustrates the percentage of players outside the reference values for the different biomarkers analysed. Magnesium, ferritin, basal cortisol, and free testosterone did not show results outside the reference values in any of the athletes. Of the total of 21 athletes, 9 of them (42.3%) showed CK values above the reference values, and 33.3% (n = 7) and 23.8% (n = 5) showed values of vitamin D and TSI, transferrin, and serum iron below the reference values, respectively. Table 2 shows the differences in anthropometric measurements, biochemical variables, and regularity of the menstrual cycle between vitamin D-deficient athletes and those who had vitamin D levels within the reference ranges. Significant differences in FM values in kilograms were only observed between athletes with optimal or deficient vitamin D levels (\(p<0.05\)). \begin{table}
\begin{tabular}{l c c c c} \hline  & **Vitamin D Deficiency * (n = 7)** & **Adequate Vitamin D * (n = 14)** & **Mann–Whitney Test** \\  & **M (Min–Max, IQR)** & **M (Min–Max, IQR)** & **U** & **_p_ \\ \hline Age & 23.00 (20.00–29.00, 3.00) & 25.00 (20.00–33.00, 4.50) & 30.00 & 0.153 \\ _Anthropometric variables_ & & & & \\ \% Fat Mass Carter & 16.76 (15.03–26.14, 5.48) & 15.71 (12.87–21.03, 3.93) & 26.00 & 0.086 \\ FM (kg) & 11.72 (8.95–19.47, 5.66) & 9.40 (7.24–13.04, 3.41) & 15.00 & 0.011 \\ FFM (kg) & 55.94 (45.85–68.48) & 49.05 (44.24–60.75, 6.17) & 24.00 & 0.062 \\ _Biochemical variables (reference values *)_ & & & & \\ Haemoglobin (12.0–16.5 g/dL) & 13.20 (11.80–14.50, 1.70) & 13.30 (12.10–14.20, 0.82) & 45.00 & 0.765 \\ Creatinine (0.55–1.02 mg/dL) & 0.91 (0.76–1.18, 0.27) & 0.94 (0.61–11.18, 0.19) & 42.00 & 0.601 \\ \hline \end{tabular}
\end{table} 
Table 2: Anthropometric, biochemical, and menstrual differences according to the vitamin D levels.