The Effect of Acute Beetroot Juice and Caffeine Supplementation on Specific Judo Performance During a Simulated Competition Day in Judo Athletes.

Beetroot juice (BJ) and caffeine (CAF) are well-established ergogenic aids for exercise performance. However, little is known about their efficacy and interaction within the specific context of a judo competition day. This study investigated the acute effects of BJ, CAF, and their combination (BJCAF) on judo-specific performance across a simulated competition day. Using a randomized, double-blind, placebo-controlled crossover design, 35 competitive judo athletes (age 23 ± 5 years; body mass 74 ± 13 kg) completed 4 sessions (BJ, CAF, BJCAF, and placebo), each consisting of 5 trials of judo randori and a Special Judo Fitness Test (SJFT), followed by neuromuscular and cognitive assessments. Compared with placebo, CAF enhanced SJFT performance, neuromuscular function, and cognition in trials 1-3 but not in trial 5 (p < 0.05). Conversely, BJ improved these same metrics in trial 5 (p < 0.05). BJCAF enhanced SJFT performance across trials 1-3 and 5, cognitive functions in trials 1, 2, and 4, and neuromuscular performance in all trials (p < 0.05). Importantly, in trial 5, both BJ and BJCAF conditions yielded improved SJFT performance, neuromuscular function, and cognitive outcomes compared to CAF alone (p < 0.05). The results demonstrate that the ergogenic effect of CAF was not maintained throughout the simulated competition day, whereas BJ provided late-stage benefits. Co-ingestion effectively counteracted the later-session decline observed with CAF alone while maintaining its early advantages. This highlights the importance of considering temporal dynamics and metabolic costs when designing nutritional strategies for multi-bout, high-intensity sports tournaments such as judo.