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 ( 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.