Background and Objective: Medium-term anaerobic power is one of the key determinants of performance in team sports such as soccer. Caffeine, as a well-known ergogenic aid, is commonly consumed orally, which may be associated with side effects in adolescent athletes. As an alternative method, caffeine mouthwash has the potential to improve performance by activating oral nerve receptors without systemic absorption. The aim of this study was to investigate the effect of caffeine mouthwash on medium-term anaerobic power indices in adolescent soccer players. Materials and Methods: This study was a crossover, double-blind, placebo-controlled clinical trial study conducted on 22 adolescent male soccer players (mean age 17.1 ± 0.9 years). Participants were randomly assigned to swish a 6 mM caffeine mouthwash or a placebo mouthwash in their mouths for 10 seconds in two separate sessions, one week apart (clean-up period). Five minutes after the mouthwash, their anaerobic power was assessed using the 30-second Wingate test. Peak power, mean power, and fatigue index were recorded, and data were analyzed using a paired t-test. Results: The results showed that the caffeine mouthwash significantly improved all performance indices compared to placebo. Peak power was 10.2 vs. 9.9 W/kg (P=0.021); and mean power was 8.5 vs. 8.1 W/kg (P=0.007); significantly increased. Also, the fatigue index in the caffeine mouthwash condition was significantly lower than the placebo condition, 45.2% versus 48% (P==0.046). Conclusion: Caffeine mouthwash solution can act as an effective and safe adjuvant to improve medium-term anaerobic power and reduce fatigue in adolescent soccer players. Due to its rapid effect and lack of systemic absorption, this method can be a practical strategy before matches or between halves to increase performance in intense and repetitive activities.
