Vitamin D Deficiency Does Not Impair Diastolic Function in Elite Athletes

<i>Background and Objectives</i>: Regular exercise is known to induce cardiovascular adaptations collectively referred to as "athlete's heart". While previous research has explored the morphological and functional cardiac adaptations in athletes, the relationship between vitamin D (25-hydroxyvitamin D [25(OH)D]) levels and echocardiographic parameters remains underexplored. This study aims to assess the association between 25(OH)D levels and structural and functional cardiac parameters using electrocardiographic (ECG) and echocardiographic evaluations in athletes. <i>Materials and Methods</i>: This case-control study included 93 male athletes, categorized into professional (<i>n</i> = 68) and recreational (<i>n</i> = 25) groups. Professional athletes were further divided into football (<i>n</i> = 19), weightlifting (<i>n</i> = 22), and running (<i>n</i> = 27) subgroups. Serum 25(OH)D levels were measured using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Standard 12-lead ECG and transthoracic echocardiography were performed to assess cardiac structure and function. Data were analyzed using statistical tests that were appropriate for normal and non-normal distributions, with a significance level set at <i>p</i> < 0.05. <i>Results</i>: Athletes exhibited higher left ventricular interventricular septum (IVS) thickness and left ventricular posterior wall thickness (LVPWd) compared to the control group. Significant differences in diastolic function parameters, including early (E) and late (A) diastolic filling velocities and the E/A ratio, were observed among athlete subgroups. The weightlifting group showed lower end-systolic diameter (ESD) values than the football group. However, no statistically significant relationship was found between 25(OH)D levels and echocardiographic diastolic parameters. While more than half of the athletes had insufficient 25(OH)D levels (<30 ng/mL), their average values were higher than those reported in previous studies. <i>Conclusions</i>: This study demonstrates that 25(OH)D levels do not significantly influence echocardiographic diastolic parameters in athletes. However, notable differences in structural and functional cardiac findings were observed among different sports disciplines. These findings contribute to the understanding of cardiac adaptations in athletes and suggest that 25(OH)D may not play a crucial role in diastolic function. Further research is needed to explore the long-term effects of vitamin D on athletic cardiac performance.