Caffeine intake enhances peak oxygen uptake and performance during high-intensity cycling exercise in moderate hypoxia

Purpose We investigated whether caffeine consumption can enhance peak oxygen uptake ( V̇O_2peak ) by increasing peak ventilation during an incremental cycling test, and subsequently enhance time to exhaustion (TTE) during high-intensity cycling exercise in moderate normobaric hypoxia. Methods We conducted a double-blind, placebo cross-over design study. Sixteen recreational male endurance athletes (age: 20 ± 2 years, V̇O_2peak : 55.6 ± 3.6 ml/kg/min, peak power output: 318 ± 40 W) underwent an incremental cycling test and a TTE test at 80