Comparison Of Vitamin D And Training Load In Division 1 Soccer Players: Starters Vs. Non-starters

Appropriate training strategies and nutrition, alongside avoiding overtraining, are crucial for athletes to maintain health and optimize safety. Training loads may vary throughout pre-season (PS); however, how individuals on the same team, particularly starters (S,>60% match starts) and non-starters (NS), experience these loads differently remain unclear. Differences in Vitamin D biomarkers between these groups throughout the season have not been well documented. PURPOSE: To assess differences in training loads and Vitamin D biomarkers between soccer S and NS. METHODS: Internal and external training loads for 20 Division I male soccer athletes (21 ± 1 years) were monitored during the 2015-16 season. Internal load (mean heart rate, HR) was recorded using Polar monitors during training sessions and games, while external load (player load, PL; velocity load, VL; player distance, PD) was measured with wearable devices equipped with GPS and accelerometers. Changes in variables were tracked at PS, Week 1 (WK1), Week 4 (WK4), Week 8 (WK8), and Week 12 (WK12), followed by group comparisons. Blood samples were collected at PS, WK1, WK4, WK8, and WK12 to assess Vitamin D levels. RESULTS: Table 2 presents training loads for both S and NS. PL changes were significantly greater for S than NS at WK1-WK4 (MD = 120.76, 95% CI = 32.20-195.73, p = 0.012), WK4-WK8 (120.76, 38.72-202.88, p = 0.009), and WK8-WK12 (145.58, 36.78-254.38, p = 0.014). DL changes were also significantly greater for S at WK1-WK4 (1678.92, 672.19-2685.64, p = 0.004), WK4-WK8 (2387.53, 847.74-3927.33, p = 0.007), and WK8-WK12 (2312.99, 1181.33-3444.64, p = 0.001). No significant differences in HR changes were observed between S and NS. No difference in Vitamin D was observed in all time points (p > 0.05). CONCLUSIONS: No differences in Vitamin D levels and training loads were observed between S and NS. Tailored training and nutrition strategies may be needed for both groups to optimize their safety and performance.