Dose-dependent effect of caffeine supplementation on judo-specific performance and training activity: a randomized placebo-controlled crossover trial

Randomised, double-blind, placebo-controlled cross-over trial in 22 healthy, highly-trained male judo athletes.

Acute pre-exercise caffeine with doses of 3, 6, or 9 mg/kg body weight, ingested 60 minutes before exercise, dissolved in 350 mL water; placebo comprised maltodextrin ingested identically.

6 mg/kg and 9 mg/kg caffeine acutely improved judo-specific performance (SJFT total throws) versus 3 mg/kg, placebo or baseline; 9 mg/kg also increased combat activity (total attacks). 3 mg/kg showed no positive effect. Habitual caffeine consumption moderated response: among caffeine consumers, only 9 mg/kg improved SJFT; among non-consumers, 6 mg/kg produced similar improvements to 9 mg/kg. Conclusion: for combat sports like judo, higher acute caffeine doses (6–9 mg/kg) are more effective than the commonly recommended 3–6 mg/kg, and habitual caffeine use influences the effective dose.

Blood caffeine concentration not measured; combat results may be influenced by opponent's experience and in-match load; fatigue from SJFT could confound sparring outcomes; carry-over effect not formally assessed; small sample size (n=22) and only male, highly trained judo athletes limit generalizability; findings pertain to acute effects and may not apply to long-term use or other populations.