The effects of pre-training breakfast consumption on executive function performance in male volleyball players

This study aimed to examine the effects of pre-training breakfast consumption on executive function performance in male volleyball players. The research was conducted between December 2024 and May 2025 with 16 male athletes aged 18–25, all actively competing in three professional clubs affiliated with the Turkish Volleyball Federation. A randomized crossover experimental design was employed, and each participant attended three separate laboratory sessions. In the first session, participants were informed about the study procedures, completed questionnaires on sociodemographic characteristics, sports history, and dietary habits, and underwent anthropometric assessments. In the second and third sessions, they were evaluated in both fasted and fed conditions in randomized order. In the fed condition, athletes consumed a standardized breakfast consisting of a sandwich and fruit juice, providing 1.5 g/kg of carbohydrates and 0.2 g/kg of protein, two hours before exercise. All sessions were conducted in the morning following an overnight fast. During each session, a 24-hour dietary recall was recorded, urine color was assessed using the Armstrong scale, anthropometric measurements were repeated, and participants completed three cognitive tests: the Stroop Test, the Trail Making Test, and the Istanbul 5-Cube Planning Test. Following the cognitive assessments, a 30-minute aerobic exercise protocol was administered at 70–80% of each participant's estimated maximum heart rate, with a pedaling cadence of 60–70 rpm. Heart rate was recorded every 2 minutes, and ratings of perceived exertion (RPE) were assessed every 10 minutes using the Borg Scale. Pre- and post-exercise body weights were measured to calculate fluid loss through sweat. Results from the Istanbul 5-Cube Planning Test indicated significant reductions in planning time (p<0.01), first move time (p<0.01), and excessive movements (p<0.05), along with a significant increase in the number of correct solutions (p<0.05) in the breakfast condition after exercise. Although similar time-based improvements were observed in the fasted condition, the increase in correct solutions was not statistically significant (p>0.05). In the Trail Making Test, a significant decrease in completion time for Form B was found only in the breakfast condition (p<0.01), with no significant differences observed in other parameters (p>0.05). In the Stroop Test, post-exercise completion times improved significantly in both conditions (p<0.05), while the number of errors and corrections remained unchanged (p>0.05). In conclusion, consuming a carbohydrate-rich breakfast before training was associated with improvements in executive function, particularly in tasks requiring planning, attention, and cognitive processing speed. Exercise itself enhanced cognitive processing time regardless of breakfast status; however, the combination of breakfast and exercise was linked to greater improvements, especially in the accuracy of responses. While short-term breakfast omission did not result in a general decline in cognitive performance, including a balanced breakfast in the morning routine—especially before training—may be an effective strategy for optimizing mental performance in athletes. This study contributes to the limited body of experimental research exploring the relationship between pre-exercise nutrition and executive function in professional team sport athletes.