Changes in Nutritional Status and Sport-Specific Performance During Ramadan in Adolescent Male Volleyball Players: A Prospective Cohort Study

Background/Objectives: Many adolescent athletes fast during Ramadan, similar to adults. However, research on Ramadan fasting during adolescence, a critical period for growth and development, is insufficient. This study aimed to examine changes in nutritional status and sport-specific performance during Ramadan in adolescent volleyball players and to explore whether these changes differed by Ramadan fasting adherence. Methods: This prospective cohort study included 35 male adolescent volleyball players (age: 16.43 ± 1.29 years, height: 1.75 ± 0.07 m, training experience: 6.20 ± 2.13 years) who fasted during Ramadan. Energy and macronutrient intake, anthropometric measurements, and sport-specific performance tests were conducted before, during, and at the end of Ramadan, and biochemical parameters were measured before and at the end of Ramadan. Results: Fat intake decreased during and at the end of Ramadan (1.60 ± 0.16 and 1.52 ± 0.15 g/kg BW, respectively; p = 0.021). Energy and macronutrient intakes were generally consistent with recommended levels, whereas fluid intake remained relatively low (1.60 ± 0.11 L, 1.35 ± 0.09 L, 1.44 ± 0.10 L, respectively). Anthropometric measurements remained unchanged. Left-hand grip strength (p = 0.006), 20 m sprint performance (p < 0.001), and agility performance (p = 0.002) decreased over the study period. Significant group effects were observed for 5 m, 10 m, and 20 m sprint, SJ, and standing long jump performances according to fasting adherence. Chloride, urea, and the BUN/creatinine ratio increased at the end of Ramadan, whereas albumin and potassium remained unchanged. Conclusions: In adolescent male volleyball players, Ramadan fasting may be associated with changes in dietary intake, certain sport-specific performance measures, and biochemical parameters potentially related to hydration status.