Combined L-carnosine and L-tyrosine supplementation as an ergogenic strategy for physical and cognitive performance under fatigue in professional football players

Abstract

Background/objectives Football performance depends on the integration of high-intensity neuromuscular output with rapid decision-making and executive control. Although L-carnosine (L-CAR) and L-tyrosine (L-TYR) have independently demonstrated ergogenic and neurocognitive benefits, evidence regarding their combined effects on both physical and cognitive performance under post-exercise fatigue in football-specific contexts remains limited. This study aimed to investigate the acute effects of L-CAR, L-TYR, and their combined supplementation on physical and cognitive performance following high-intensity exercise in professional football players. Methods Twenty-four male professionals completed a randomized, double-blind, placebo-controlled crossover trial involving four conditions (L-CAR, L-TYR, L-CAR+L-TYR, placebo). After supplementation, participants completed a Wingate-based fatigue protocol to assess anaerobic performance (peak power, mean power), followed by sprint tests (10-30 m; sprint time), an agility assessment (completion time), and football-specific passing accuracy tasks (execution time and accuracy). Executive function was evaluated using the Stroop test, including reaction time and error rates under neutral, congruent, and incongruent conditions. Results L-CAR significantly enhanced anaerobic power and agility, whereas L-TYR primarily improved cognitive performance. The combined condition produced the most pronounced effects, increasing peak power by similar to 17% and average power by similar to 16% versus placebo, reducing sprint and agility times by similar to 7-13%, and shortening incongruent Stroop reaction time by similar to 15%. Perceived exertion was lower with combined supplementation, while blood lactate concentrations did not differ significantly between conditions.