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. 2021 Aug 25;13(9):2944. doi: 10.3390/nu13092944

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.