Habitual Caffeine Consumption and Training Status Affect the Ergogenicity of Acute Caffeine Intake on Exercise Performance.

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.