Effects of Caffeine on Durability After a Simulated Race in Trained Cyclists: A Field-Based Cross-Over Randomized Controlled Trial.

Preexercise caffeine intake has proven to exert ergogenic effects on cycling performance. However, controversy exists on whether caffeine ingested during prolonged exercise could attenuate performance decrements. We aimed to assess the effect of caffeine ingested during prolonged cycling on subsequent time-trial (TT) performance in trained cyclists. The study followed a triple-blinded, randomized, placebo-controlled cross-over design. Thirteen well-trained Junior cyclists (16.3 ± 0.5 years) performed a field-based 8-min TT under "fresh" conditions and after two work-matched field-based bouts designed to simulate a short cycling race (total energy expenditure of ∼20 kJ/kg and ∼90-min duration). During the latter sessions, participants consumed caffeine (6 mg/kg) or a placebo ∼60 min before the TT. We assessed power output, heart rate, and rating of perceived exertion during the TT and mood state (Brunel Mood Scale) before and after each TT. Participants attained a lower average power output during the TT with the placebo (352 ± 34 W) compared with the fresh condition (367 ± 36 W, p = .009, Cohen's d = 1.02), whereas this decline was not observed in the caffeine condition (363 ± 40 W, p = 1.000, vs. fresh, d = 0.25). Differences between the caffeine and placebo conditions did not reach statistical significance (p = .103), although they were moderate (3.1%, d = 0.66) and surpassed the estimated smallest worthwhile change (defined as 2%). No significant differences were found for heart rate, rating of perceived exertion, or mood states. High-dose caffeine intake during a simulated cycling race seems to partly attenuate performance impairments on subsequent TT in Junior cyclists, although further research is needed to confirm its effectiveness compared with a placebo.