Table A1.
Investigations in endurance-based sports disciplines.
| Study | Participants | Habituation to Caffeine | Study Design | Sport | Supplementation | Dose | Main Outcome |
|---|---|---|---|---|---|---|---|
| Arazi et al. (2016) [31] | 36 females 14 ± 1 years |
Not reported | DB, R, Cx | Swimming | Big Bear energy drink or placebo, consumed 15 min before exercise | 78 mg | Time decrease in a 100 m crawl velocity test |
| Hulston and Jeukendrup (2008) [35] | 10 males 27 ± 7 years |
All subjects were identified as caffeine users to varying extent (186 ± 101 mg·day−1, range = 70–400 mg·d−1) |
DB, R, Cx | Cycling | Glucose drink with or without caffeine or placebo, consumed at the start and during exercise | 5.3 mg·kg−1 | Performance improvement in a time trial |
| Cureton et al. (2007) [12] | 16 males 28 ± 7 years |
Habitually caffeine users (150 ± 113 mg·day−1, range = 9–482 mg·day−1) | DB, Cx | Cycling | Sports drink with caffeine (C + C) and without caffeine (CHO) or placebo, consumed before exercise | 195 mg·L−1 | Greater mean total work performed during a 15 min ride for the C + C trial |
| Ivy et al. (2009) [47] | 6 males and 6 females 27 ± 2 years |
Not reported | DB, R, Cx | Cycling | Red Bull energy drink or placebo consumed 40 min before exercise | 160 mg | Performance improvement in a time trial |
| Schubert et al. (2013) [51] | 6 males 23 ± 2 years |
Mean daily caffeine intake of 80 mg·day −1 | SB, R, Cx | Running | Yerba MatéOrganic Energy Shot (YM), Red Bull Energy Shot (RB), or a placebo, consumed 1 h before exercise | YM = 140 mg, RB = 80 mg | No significant difference in time-trial performance |
| Phillips et al. (2014) [54] | 11 males 33 ± 9 years |
Between 80 and 350 mg·day−1 | SB, R, Cx | Cycling | Red Bull energy drink (RB), Cola drink (CD), or placebo, consumed 50 min before exercise | RB = 160 mg, CD = 160 mg | No significant difference in a simulated road race |
| Prins et al. (2016) [56] | 13 males and 5 females 20 ± 3 years |
Noncaffeine users (n = 1), low-to-moderate–caffeine users (50–200 mg·day−1; n = 13) and high-caffeine users (>200 mg·day−1; n = 4) | DB, R, Cx | Running | Red Bull energy drink or placebo, consumed 1 h before the trial | 160 mg | Improvement in a 5-km treadmill running time |
| Quinlivan et al. (2015) [57] | 11 males 32 ± 6 years |
Regular caffeine consumers (mean caffeine consumption 295 mg·day−1) | DB, R, Cx | Cycling | Red Bull energy drink (RB), anhydrous caffeine (AC), or placebo, consumed 90 min before the trial | RB = 3 mg·kg−1,AC = 3 mg·kg−1 | Significant improvement in time to complete a cycling trial |
| Rica et al. (2019) [59] | 55 males and females 33 ± 6 years |
Not reported | DB, R, Cx | Running | Energy drink or a placebo, consumed 1 h before exercise | 80 mg | No significant improvement in the Cooper test |
| Sheehan and Hartzler (2011) [60] | 9 males and 3 females 21 ± 2 years |
Not reported | DB, R, Cx | Running | Cherry Blast XS® energy drink or a placebo, consumed 30 min before the trial | 80 mg | No significant increase in VO2max |
| Talanian and Spriet (2016) [21] | 11 males and 4 females 23 ± 1 years |
Only one subject was a habitual caffeine user (>50 mg·day−1) | DB, R, Cx | Cycling | Two caffeinated carbohydrate-electrolyte drinks (CE1 and CE2) or a placebo, consumed during exercise | CE1 = 100 mg, CE2 = 200 mg | Performance improvement in a cycling time trial |
DB = double-blinded, SB = single-blinded, R = randomized, Cx = crossover.