Background: Acute caffeine ingestion can improve exercise performance. Interplay between caffeine habituation and training status on the performance-enhancing effect of caffeine is unknown. Hypothesis: Habitual caffeine consumption and training status affect the ergogenicity of pre-exercise caffeine intake on exercise performance. Study Design: Double-blind, placebo-controlled, counterbalanced experimental design. Level of Evidence: Level 3. Methods: Eighty physically inactive men were randomized into 1 of 4 groups: caffeine supplementation (CAF), caffeine supplementation + exercise training (CAFEXE), placebo (PLA), and placebo + exercise training (PLAEXE); high-intensity interval training and caffeine were administered for 9 and 8 weeks, respectively. Data were collected pre-test, mid-test, post-test, and delayed post-test, each including 2 experiment sessions (3 mg/kg caffeine or placebo), with an additional experiment session post-test (6 mg/kg caffeine). In each experiment session, 45-min after consuming a placebo or caffeine, a 3-km running test and a Wingate power test were performed. Results: Pre-exercise ingestion of 3 mg/kg caffeine improved 3-km running time and mean power output (MPO) in all groups at all stages ( P < 0.05); this effect was higher in trained than in untrained volunteers ( P < 0.05). Habitual caffeine consumption reduced the ergogenic effect of caffeine in both aerobic and anaerobic trials ( P < 0.05); 6 mg/kg caffeine enhanced this decrease only in CAFEXE ( P < 0.05). Short-term caffeine withdrawal augmented the reduced ergogenic effect of caffeine on 3-km running performance and MPO in CAF and CAFEXE ( P < 0.05). Conclusion: Habituation to caffeine and training status could partially influence the ergogenic effects of caffeine on exercise performance. Clinical Relevance: Regular caffeine consumption leads to some degree of tolerance and decreases its ergogenicity. A pre-exercise increase in caffeine dosage in trained people and short-term caffeine withdrawal in both trained and untrained people could compensate for the reduced caffeine ergogenicity in young men.

Purpose: This study aimed to investigate how genotype and caffeine habituation influence the acute effects of caffeine ingestion on exercise-induced hemostatic responses in individuals with obesity. Methods: Using a randomized, double-blind, placebo-controlled crossover design, 40 physically inactive young men with obesity (age, 22.2 ± 2.3 yr; body mass index, 34.1 ± 2.7 kg·m ⁻² ) completed two moderate-to-high-intensity concurrent exercise sessions following ingestion of caffeine (3 mg·kg ⁻¹ ) or placebo. Blood samples were collected at baseline, after exercise, and after 60 min of recovery. Statistical analysis was performed by repeated-measures multivariate analysis of variance. Results: Acute exercise increased platelet count and aggregation, fibrinogen, F1 + 2, tPA antigen, D-dimer, and clot lysis time, regardless of genotype or caffeine habituation status ( P < 0.05). PAI-1 antigen remained unchanged after exercise ( P > 0.05) but decreased following recovery ( P < 0.01). Caffeine resulted in a greater increase in platelet aggregation, fibrinogen, F1 + 2, and clot lysis time, alongside a blunted increase in tPA antigen levels post-exercise in naïve consumers ( P < 0.05). In contrast, habitual caffeine consumers exhibited a mitigated increase in clot lysis time and a greater post-recovery reduction in PAI-1 antigen following caffeine ingestion ( P < 0.001). Caffeine’s impact on hemostatic responses to exercise was unaffected by genotype ( P > 0.05). Conclusions: Moderate-to-high-intensity concurrent exercise induces a transient prothrombotic state in physically inactive individuals with obesity. Acute caffeine supplementation at a moderate dose modulates the hemostatic responses depending on caffeine habituation status rather than CYP1A2 genotype: it exacerbates the prothrombotic response in naïve consumers but attenuates it in habitual consumers.

The ability of nitrate (NO₃⁻)-rich beetroot juice (BJ) to improve exercise depends on training status. However, the mechanisms are understudied. The aim of this study was to investigate the impact of acute BJ supplementation on the Special Judo Fitness Test (SJFT) outcomes in elite and recreational judokas.Forty judo athletes (17 elite and 23 recreational) completed two SJFT sessions after drinking either BJ or a placebo in a randomized, double-blind, placebo-controlled crossover design. Plasma NO₃⁻ and lactate, tissue saturation index (TSI) and SJFT outcomes were measured. Plasma NO₃⁻ increased after BJ intake in both groups (p < 0.001). Elite athletes achieved more total throws (TT) (p < 0.05) and exhibited lower TSI during SJFT, 1-min post-SJFT heart rate (HR₁), and SJFT index (p < 0.05), but higher post-SJFT lactate and TSI than recreational athletes (p < 0.05). TT did not improve following supplementation (p > 0.05). BJ increased post-SJFT TSI (elite: 2.6 ± 3% vs. recreational: 4.55 ± 2.6%) and reduced HR₁ (elite: - 5.6 ± 3.3% vs. recreational: - 9.8 ± 4.7%) and SJFT index (elite: - 2.7 ± 5.6% vs. recreational: - 6 ± 5.8%) overall (p < 0.001 compared to placebo), with greater effects in recreational athletes (p < 0.05). BJ also decreased post-SJFT lactate only in recreational athletes (p < 0.01). Higher maximal oxygen uptake correlated with smaller BJ-induced improvements in lactate (r = - 0.57, p < 0.001), HR₁ (r = - 0.50, p < 0.001), SJFT index (r = - 0.43, p < 0.01), and TSI during the third period of SJFT effort (r = - 0.5, p < 0.001) and during 1-min recovery (r = - 0.35, p < 0.05). BJ primarily attenuates the physiological cost and enhances recovery-related markers during the judo performance, rather than directly increasing the performance, with responsiveness modulated by training status.

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.