Caffeine Increases Performance and Leads to a Cardioprotective Effect During Intense Exercise in Cyclists: a Randomized, Double-blind, Crossover, Placebo-controlled Study

The present study was designed to investigate the effects of different caffeine dietary strategies to compare the impact on athletic performance and cardiac autonomic response. The order of the supplementation was randomly assigned: placebo(4-day)-placebo(acute)/PP, placebo(4-day)-caffeine(acute)/PC and caffeine(4-day)-caffeine(acute)/CC. Fourteen male recreationally-trained cyclists ingested capsules containing either placebo or caffeine (6 mg∙kg − 1) for 4 days. On day 5 (acute), capsules containing placebo or caffeine (6 mg∙kg − 1) were ingested 60 min before completing a 16km time-trial. CC and PC showed improvements in time (CC vs PP, Δ -39.3 s and PC vs PP, Δ -43.4 s; p = 0.00; ƞ2=0.33) and in output power (CC vs PP, Δ 5.55 w and PC vs PP, Δ 6.17 w; p = 0.00; ƞ2=0.30). At the final of the time-trial, CC and PC exhibited greater parasympathetic modulation (vagal tone) when compared to the PP condition (p < 0.00; ƞ2=0.92). Our study provided evidence that acute caffeine intake (6 mg∙kg − 1) increased performance and demonstrated a relevant cardioprotective effect, through increased vagal tone.