Caffeine vs. carbohydrate mouth-rinsing in soccer: effects on passing performance and psychophysiological responses in youth players

OpenAlex İngilizce

Abstract Purpose This study aimed to evaluate the effects of caffeine (CAF) and carbohydrate (CHO) mouth-rinsing on soccer passing performance and psychophysiological responses using the Loughborough Soccer Passing Test (LSPT). Design/methodology/approach Twenty-five well-trained male youth soccer players (age: 16.6 ± 0.5 years) participated in a randomized, double-blind, crossover trial involving three experimental conditions: CAFF-MR (1.2% caffeine solution; 25 mL, equivalent to 300 mg caffeine), CHO-MR (6% glucose solution), and a control condition (water rinse). Execution time, penalty time, total time, rating of perceived exertion (RPE), enjoyment, mental fatigue, and heart rate-derived variables were assessed. Findings Execution time differed significantly across conditions (F = 7.52, p < 0.001, η 2 = 0.239), with both CAFF-MR and CHO-MR showing lower execution times than the control condition. Penalty time was also significantly different between conditions (F = 7.22, p = 0.002, η 2 = 0.231), with lower values in CAFF-MR than in the control condition. Total LSPT performance time, the primary outcome, also differed significantly between conditions overall (F = 9.89, p = 0.003, η 2 = 0.289). RPE differed significantly between conditions (F = 6.27, p = 0.004, η 2 = 0.207), with lower values in CAFF-MR than in the control condition. Enjoyment also differed significantly between conditions (F = 3.59, p = 0.035, η 2 = 0.130), with higher values in the control condition than in CHO-MR. No significant differences were observed for mental fatigue, %HR, or mood state profiles. Originality/value These findings suggest that caffeine mouth-rinsing may improve selected aspects of soccer-specific passing performance under controlled conditions in youth soccer players, particularly execution time, penalty time, and perceived exertion. Carbohydrate mouth-rinsing may also influence execution time, although its effects appear less consistent across the remaining outcomes. This study adds to the limited evidence on mouth-rinsing strategies in youth soccer and provides a direct comparison between CAFF-MR and CHO-MR using a standardized soccer-specific passing test. Trial registration ClinicalTrials.gov NCT06881316. Registered on [February, 25th of 2025]. Retrospectively registered.