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.