Introduction
Caffeine in sport: a brief history
Caffeine sources
Caffeine legality in sport
Caffeine pharmacokinetics
Mechanism of Action (MOA)
The placebo effect
Caffeine and endurance exercise
Caffeine and muscular endurance, strength and power
Caffeine and sport-specific performance
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Soccer – increased total distance covered during the game, increased passing accuracy, and jumping height [94, 243, 244], but the consumption of a caffeinated energy drink did not enhance performance in the “T test” in female soccer players [245], nor during match play in young football players [246]
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Football - did not improve performance for anaerobic exercise tests used at the NFL Combine [251]
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Ice-hockey - has limited impact on sport-specific skill performance and RPE, but may enhance physicality during scrimmage [257]
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Combat sports – increased number of offensive actions and increased the number of throws [258]
Interindividual variation in response to caffeine
Genetics
Caffeine, genetics and anxiety
Habitual caffeine intake
Caffeine timing
Training status
Caffeine and sleep
Side-effects associated with caffeine intake
Caffeine and cognitive performance
Author | Participants | Protocol | Outcome |
---|---|---|---|
Sleep Deprived | |||
Hogervorst et al. 2008 [82] | Well-trained cyclists (n = 24) | • Bar with 100 mg caffeine and 45.0 g CHO • Bar with only 45.0 g CHO • 300 mL non-caloric beverage | *↑Stroop and Rapid Visual Information Processing tests after 140 min and time to exhaustion exercise trial at 75% VO2max |
McLellan et al. 2007 [334] | Soldiers (n = 20) | • 600 mg total caffeine in 200 mg does over 6 h period • Placebo | *↑ Increased vigilance |
McLellan et al. 2005 [329] | Soldiers (n = 31) | • 200 mg caffeine (gum) mg doses over 5 h • Placebo | Maintained vigilance in control observation and reconnaissance vigilance task |
McLellan et al. 2005 [330] | Soldiers (n = 30) | • 600 mg total caffeine in 100 mg and 200 mg doses over a 6 h period • Placebo | Sustained marksmanship vigilance and accuracy *less decrease in urban operations vigilance |
Lieberman et al. 2002 [42] | U.S. Navy SEAL trainees (n = 68) | • 100 mg caffeine • 200 mg caffeine • 300 mg caffeine • Placebo | *↑improved vigilance and reaction time in both the 200 and 300 mg caffeine interventions following 72 h sleep deprivation |
Kamimori et al. 2015 [332] | Special Forces Operators (n = 20) | • Four 200 mg doses of caffeine • Placebo | *maintained psychomotor speed, improved event detection, increased the number of correct responses to stimuli, and increased response speed during logical reasoning tests. ⬌Live-fire marksmanship was not altered by caffeine. |
Tikuisis et al. 2004 [335] | Young Military Subjects (n = 20) | • 400 mg caffeine • 100 mg caffeine • 100 mg of caffeine • Placebo | *increased cognitive component of shooting task |
Not Sleep Deprived | |||
Share et al. 2009 [336] | Elite male shooters (n = 7) | • 2 mg/kg caffeine • 4 mg/kg caffeine • Placebo | ⬌ shooting accuracy, reaction time, or target tracking time between groups |
Pomportes et al. 2019 [337] | Modern pentathlon national team athletes (n = 10) | • Four counterbalanced sessions with: • 30 g CHO • 300 mg guarana complex • 200 mg caffeine • Placebo | * enhanced speed of information processing w CHO, and caffeine and guarana complex * lower RPE w caffeine and gaurana complex |
Younger males (n = 12) | • 5 mg/kg dose caffeine • Placebo 60 min before 30 s upper body Wingate anaerobic test | *Readiness to invest physical effort, and cognitive performance *Reduced rating of perceived exertion ⬌Response accuracy | |
Other Stressors | |||
Share et al. 2009 [336] | Elite male shooters (n = 7) | • 2 mg/kg caffeine • 4 mg/kg caffeine • Placebo | ⬌ shoot accuracy, reaction time, or target tracking time between groups |
Gillingham et al. 2004 [339] | Military reservists (n = 12) | • 5 mg/kg caffeine or placebo dosed before 2.5 h loaded march plus 1 h sandbag wall construction task then re-dose of 2.5 mg/kg caffeine or placebo | *↑ marksmanship performance (engagement time and number of shots fired) ⬌friend-foe discrimination |
Zhang et al. 2014 [340] | Firefighters (n = 10) | • 400 mg caffeine • Menthol lozenges • Placebo | ⬌ Change in perceived exertion, mood reaction time, short-term memory, or retrieval memory |
Crowe et al. 2006 [341] | Healthy subjects: male (n = 12) female (n = 5) | • 6 mg/kg caffeine • Placebo | ⬌ rating of perceived exertion |
Foskett et al. 2009 [244] | Male soccer players (n = 12) | • 6 mg/kg of caffeine • Placebo | * Enhanced fine motor skills via improved ball passing accuracy and control |
Stuart et al. 2005 [342] | Competitive male rugby (n = 9) | • 6 mg/kg caffeine • Placebo | *Increased ball-passing accuracy |
Duvnjak-Zaknich et al. 2011 [343] | Moderately trained male athletes (n = 10) | • 6 mg/kg caffeine • Placebo | *Main effect for condition on decision time |
Environmental influences on response to caffeine
Heat
Author | Participants | Protocol | Outcome |
---|---|---|---|
Cohen et al. 1996 [362] | Endurance trained competitive road racers (male = 5; female = 2) | • Placebo • 5 mg/kg caffeine • 9 mg/kg caffeine | ⬌ Running performance |
Del Coso et al. 2008 [363] | Endurance trained male cyclists (n = 7) | • No fluid • Water • 6%CHO Solution • No fluid + 6 mg/kg caffeine capsule • Water + 6 mg/kg caffeine capsule • 6%CHO solution + 6 mg/kg caffeine capsule | ⬌ Maximal voluntary contraction in heat *↑ Maximal cycling power in heat *↑ Maximal leg force via voluntary activation ONLY in water + caffeine and 6%CHO + caffeine |
Cheuvront et al. 2009 [364] | Healthy males (n = 10) | • 9.0 mg/kg caffeine • Placebo | ⬌ TT performance ⬌ RPE |
Ganio et al. 2011 [365] | Male cyclists (n = 11) | • Participants consumed either 3 mg/kg caffeine or placebo 60 min prior to and after 45 min of the following trials (4 trials total; total 6 mg/kg): • Warm environment (33 °C): 90 min cycling followed by 15 min performance trial • Cool environment (12 °C): 90 min cycling followed by 15 min performance trial | Caffeine *↑ increased performance versus placebo independent of temperature |
Roelands et al. 2011 [265] | Trained male cyclists or triathletes (n = 8) | • 6 mg/kg caffeine • Placebo | ⬌ Acute cycling TT performance |
Pitchford et al. 2014 [366] | Well-trained males (n = 9) | • 3 mg/kg caffeine • Placebo | ⬌cycling TT performance in heat |
Suvi et al. 2017 [359] | Healthy males (n = 13) and females (n = 10) | • 6 mg/kg caffeine • Placebo | ⬌ Time to walking exhaustion |
Recreationally active males (n = 8) | • 6 mg/kg caffeine • Placebo | *↑ Endurance cycle performance in heat *↓ RPE during initial 60 min of exercise |
Altitude
Author | Participants | Protocol | Outcome |
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Berglund et al. 1982 [370] | Well-trained cross-country skiers (n = 14) | • 6 mg/kg caffeine • Placebo | *↑ 21 km TT 2900 m above sea level |
Fulco et al. 1994 [371] | Young adult cyclists (n = 8) | • 4 mg/kg caffeine • Placebo | *↑ Time to exhaustion at 80% of their altitude-specific VO2max at 4300 m above sea level |
Stadheim et al. 2015 [211] | Male sub-elite cross-country skiers (n = 13) | • 4.5 mg/kg caffeine • Placebo | *↑ Double-poling time to task failure at 2000 m above sea level |
Smirmaul et al. 2017 [372] | Adult male volunteers (n = 7) | • 4.0 mg/kg caffeine • Placebo | *↑ Time to exhaustion during cycling by 12% |
Alternate caffeine sources
Caffeinated chewing gum
Author | Participants | Protocol | Results |
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Kamimori et al. 2002 [58] | Healthy males (n = 84; 12 per group) | • 50 mg caffeine capsule • 50 mg caffeine gum • 100 mg caffeine capsule • 100 mg caffeine gum • 200 mg caffeine capsule • 200 mg caffeine gum • Placebo | Both 100 and 200 mg of caffeine in gum and capsule formualtions provide comparable amounts of caffeine to the systemic circulation. Mean Tmax for the gum groups ranged from 44.2 to 80.4 min as compared with 84.0–120.0 min for the capsule groups |
Ryan et al. 2012 [59] | College-aged, physically active males (n = 8) | • 200 mg caffeinated gum • Placebo gum | ⬌ cycling TTE |
Ryan et al. 2013 [60] | Well-trained male cyclists (n = 8) | • 300 mg caffeine gum • Placebo gum | *↑ cycling TT performance when 300 mg caffeine chewing gum was administered 5 min pre-TT |
Lane et al. 2014 [61] | Well-trained males (n = 12) and females (n = 12) | • 3 mg/kg caffeine gum 40 min prior + 1 mg/kg 10 min prior • Placebo gum • Beet root juice • Beet root juice w/ caffeine | *↑ cycling TT performance by 3–4% Note: participant’s sex was accounted for during testing (female: 29.35 km; male: 43.83 km) |
Oberlin-Brown et al. 2016 [62] | Well-trained male cyclists (n = 11) | • 200 mg caffeine gum • 200 mg caffeine + CHO gum • CHO gum • Placebo gum | ⬌ cycling TT performance |
Paton et al. 2015 [63] | Well-trained male (n = 10) and female (n = 10) cyclists | • ~ 3–4 mg/kg caffeine gum • Placebo gum | ~ 3–4 mg/kg enhanced both endurance (> 5 min) and sprint power output (< 30 s) by similar amounts (~ 4%) during the final 10 km of a 30-km race |
Paton et al. 2010 [64] | Competitive male cyclists (n = 9) | • 3 mg/kg caffeine gum • Placebo gum | *↓ power output decline in 3rd & 4th sprints |
Bellar et al. 2012 [65] | Collegiate shot-put athletes (n = 9) | • 100 mg caffeine gum • Placebo gum | *↑ shot-put performance |
Ranchordas et al. 2018 [66] | Collegiate male soccer players (n = 10) | • 200 mg caffeine gum • Placebo gum | *↑ Yo-Yo Intermittent Recovery Test level 1 and countermovement jump |
Resistance-trained men (n = 19) | • 300 mg caffeine gum • Placebo gum | *↑ Jumping height *↑ Isokinetic strength and power *↑ Movement velocity in the bench press *↑ Whole-body power output |
Caffeine mouth rinsing
Author | Participants | Protocol | Results |
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Doering et al. 2014 [69] | Well-trained cyclists (n = 10) | • 10 s rinse 35 mg caffeine/25 mL X 8 • Placebo rinse | ⬌ plasma caffeine levels ⬌ cycling TT Performance |
De Pauw et al. 2015 [70] | Healthy males (n = 10) | • 20 s- 25 mL Rinse 1.2% caffeine • 20 s- 25 mL Rinse 6.4% CHO • Placebo Rinse | *↑ stroop task performance |
Pomportes et al. 2017 [71] | Physically active males (n = 16) and females (n = 6) | • 20 s- 25 mL rinse 67 mg caffeine • 20 s- 25 mL rinse 7.0% CHO • 20 s- 25 mL rinse 0.4 g guarana • Placebo rinse | ⬌ variability or production durations ⬌ errors made |
Beaven et al. 2013 [72] | Recreationally active males (n = 12) | • 5 s- 25 mL rinse 1.2% caffeine • 5 s- 25 mL rinse 6% CHO • Placebo rinse | *↑ mean power in first sprint for caffeine and CHO rinses NS ↑ maximal power in first two sprints |
Beaven et al. 2013 [72] | Recreationally active males (n = 12) | • 5 s- 25 mL rinse 1.2% caffeine • 5 s- 25 mL rinse 6.0% CHO • 5 s- 25 mL rinse 1.2% caffeine + 6.0% CHO | *↑ peak power in first sprint *↑ mean power in fifth sprint |
Kizzi et al. 2016 [73] | Glycogen depleted, recreationally active males (n = 8) | • 10 s- 25 mL rinse 2.0% caffeine • Placebo rinse | ⬌ mean and peak power in 4th and 5th sprint |
Sinclair and Bottoms 2014 [74] | Healthy males (n = 12) | • 5 s- 25 mL rinse 0.032% caffeine • 5 s- 25 mL rinse 6.4% CHO • Placebo rinse | *↑ arm crank TT performance |
Bottoms et al. 2014 [74] | Healthy males (n = 12) | • 5 s- 125 mL rinse w/ 32 mg of caffeine • 5 s – 6.4% CHO solution • Placebo rinse | *↑ distance cycled during the caffeine mouth rinse trial (16.2 ± 2.8 km) was significantly greater compared to placebo trial (14.9 ± 2.6 km). There was no difference between CHO and caffeine trials |
Pataky et al. 2016 [75] | Recreationally trained male (n = 25) and female (n = 13) cyclists | • Placebo rinse + 6 mg/kg caffeine capsule • 25 mL rinse 300 mg caffeine + placebo capsule • 25 mL rinse 300 mg caffeine + 6 mg/kg caffeine capsule | *↑ 3 km cycling TT performance |
Lesniak et al. 2016 [76] | Recreationally active females (n = 7) | • 5 s- 25 mL rinse 1.2% caffeine • 5 s- 25 mL rinse 6.0% CHO • 5 s- 25 mL rinse 1.2% caffeine + 6% CHO | ⬌ cycling TT performance |
Dolan et al. 2017 [77] | College lacrosse players (n = 10) | • 5 s- 25 mL Rinse 1.2% caffeine • 5 s- 25 mL Rinse 6.0% CHO • 5 s- 25 mL Rinse 1.2% caffeine + 6.0% CHO • Placebo rinse • No rinse | ⬌ intermittent sport performance |
Clarke et al. 2015 [78] | Recreationally resistance-trained males (n = 15) | • 5 s- 25 mL rinse 1.2% caffeine • 5 s- 25 mL rinse 6.0% CHO • 5 s- 25 mL rinse 1.2% caffeine + 6.0% CHO • Placebo rinse | ⬌ total weight lifted |
Caffeinated nasal sprays and inspired powders
Author | Participants | Protocol | Results |
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De Pauw et al. 2017 [79] | Healthy males (n = 10) | • Nasal spray 15 mg/mL caffeine • Nasal spray 80 mg/mL glucose • Placebo nasal spray | *↑ activity of cingulate, insular, and sensory-motor cortices ⬌ stroop task performance |
De Pauw et al. 2017 [80] | Moderately trained males (n = 11) | • Nasal spray 15 mg/mL caffeine • Nasal spray 80 mg/mL glucose • Placebo nasal spray | ⬌ plasma caffeine levels ⬌ wingate performance ⬌ 30 min cycling TT performance ⬌ stroop task performance |
Laizure et al. 2017 [81] | Healthy adults (n = 17) | • Inspired powder 100 mg/mL caffeine (AeroShot) • Oral solution 100 mg/248 mL caffeine | ⬌ peak plasma caffeine levels ⬌ bioavailability |
Caffeinated gels
Author | Participants | Protocol | Results |
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Hogervorst et al. 2008 [82] | Well-trained male cyclists (n = 24) | • Bar with 100 mg caffeine and 45.0 g CHO • Bar with only 45.0 g CHO • 300 mL non-caloric beverage | *↑Stroop and Rapid Visual Information Processing tests after 140 min and time to exhaustion exercise trial at 75% VO2max |
Cooper et al. 2014 [83] | Recreationally trained males (n = 12) | • Gel with 100 mg caffeine and 25.0 g CHO • Gel with 25 g CHO • Gel placebo | *↓ fatigue and RPE during 3rd sprint set NS: sprint performance |
Scott et al. 2015 [84] | Male college athletes (n = 13) | • Gel with 21.6 g CHO and 100 mg caffeine • Gel with 21.6 g CHO | *↑ performance in 2000 m rowing task |
Resistance-trained men (n = 17) | • Gel with 88 g CHO and 300 mg caffeine • Gel with 88 g CHO | *↑ jumping height *↑ isokinetic strength and power *↑ movement velocity in the bench press NS: whole-body power output |
Caffeinated bars
Caffeine in combination with other ingredients
Caffeine and Creatine
Caffeine and carbohydrate
Caffeine within brewed coffee
Caffeine containing energy drinks and pre-workouts
Author | Participants | Protocol | Results | Other supplements | |
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Endurance Exercise Performance | Alford et al. 2001 [85] | Young adults (n = 36) | -250 mL Energy drink with 80 mg caffeine and 26 g CHO -Carbonated placebo -No drink | *↑ Aerobic Endurance | -26 g CHO |
Candow et al. 2009 [86] | Young men (n = 9) and women (n = 8) | -CHO free energy drink with 2 mg/kg caffeine -Non-caffeinated version of energy drink | ⬌ High-intensity Run Time to Exhaustion | ||
Walsh et al. 2010 [87] | Recreationally active men (n = 9) and women (n = 6) | -26 g Pre-workout with unknown amount of caffeine (ingredients listed in column 5) -Placebo | *↑ Mod-intensity Run Time to Exhaustion | −2.05 g taurine, caffeine, and gluconolactone, 7.9 g L-leucine, L-isoleucine, L-valine, L-arginine and L-glutamine, 5 g of di-creatine citrate, and 2.5 g of βalanine | |
Ivy et al. 2009 [88] | Trained cyclists men (n = 6) and women (n = 6) | -Energy drink with 160 mg caffeine -Placebo | *↑ Cycle Time Trial Performance by 4.7% | -2.0 g taurine, 1.2 g glucuronolactone, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 microg vitamin B12 | |
Sanders et al. 2015 [89] | Healthy participants (n = 15) | −12 oz. Placebo (Squirt) − 8.4 oz. Red Bull® − 16 oz. Monster Energy® − 2 oz. 5-h ENERGY® | ⬌ RPE on Treadmill at 70% VO2 max ⬌ Oxygen Consumption at 70% VO2 max | ||
Al-Fares et al. 2015 [90] | Healthy female students (n = 32) | -Energy drink with 160 mg caffeine -Placebo with similar CHO content | ⬌ VO2 max | −2.0 g taurine, 1.2 g glucuronolactone, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 μg vitamin B12 | |
Prins et al. 2016 [91] | Recreation endurance male (n = 13) and female (n = 5) runners | -Energy drink with 160 mg caffeine -Placebo | *↑ 5 k Time Trial | −2.0 g taurine, 1.2 g glucuronolactone, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 microg vitamin B12 | |
Kinsinger et al. 2016 [92] | Recreational male athletes (n = 23) | −1.93 oz Energy shot with 100 mg caffeine − 1.93 oz. Placebo | ⬌ RPE on Treadmill VO2 max Test ⬌ Treadmill VO2 max | -1870 mg (taurine, glucuronic acid, malic acid, N-acetyl L-tyrosine, L-phenylalanine and citicoline) | |
Resistance/Sprint Performance | Forbes et al. 2007 [93] | Young men (n = 11) and women (n = 40 | -Energy drink with 2 mg/kg caffeine -Non-caffeinated version of energy drink | *↑ Bench-Press Repetitions by 6% | |
Del Coso et al. 2012 [94] | Healthy men (n = 9) and women (n = 3) | -Energy drink with 1 mg/kg caffeine -Energy drink with 3 mg/kg caffeine -Non-caffeinated version of energy drink | *↑ Half-Squat Maximal Power by 7% *↑ Bench-Press Maximal Power by 7% | ||
Gonzalez et al. 2011 [95] | Resistance-trained college males (n = 8) | −26 g Pre-workout with unknown amount of caffeine (ingredients listed in column 5) -Placebo | *↑ # of Bench-Press and Squat Repetitions at 80% 1RM by 11.8% *↑ Average Power Output for the Workout | -2.05 g taurine, caffeine, and gluconolactone, 7.9 g L-leucine, L-isoleucine, L-valine, L-arginine and L-glutamine, 5 g of di-creatine citrate, and 2.5 g of βalanine | |
Astorino et al. 2011 [96] | Collegiate female soccer players (n = 15) | -255 mL energy drink with 1.3 mg/kg caffeine + 1 g taurine -Placebo | ⬌ Sprint-based Exercise Performance | -1 g taurine | |
Campbell et al. 2016 [97] | College men (n = 8) and women (n = 11) | -37 mL Energy shot with 2.4 mg/kg caffeine -37 mL Placebo | ⬌ Vertical Jump ⬌ YMCA Bench-Press NS↑ Curl-up Endurance | ||
Eckerson et al. 2013 [98] | Resistance-trained men (n = 17) | −500 mL Energy drink with 160 mg caffeine + 2 g taurine − 500 mL Energy drink with 160 mg caffeine − 500 mL Placebo | ⬌ 1RM Bench-Press Strength ⬌ Total Volume Lifted | −2 g Taurine | |
Astley et al. 2018 [99] | Resistance-trained men (n = 15) | -Energy drink with 2.5 mg/kg caffeine -Non-caffeinated version of energy drink | *↑ Knee Extensions in Dominant Leg *↑ 80% 1RM Bench-Press Reps *↑ Isometric Grip Strength | ||
Magrini et al. 2016 [100] | Healthy men (n = 23) and women (n = 8) | -4 oz Energy drink with 158 mg caffeine -4 oz. Placebo | ⬌ Total Push-ups | ||
Anaerobic Exercise Performance for Power | Forbes et al. 2007 [93] | Young men (n = 11) and women (n = 4) | -Energy drink with 2 mg/kg caffeine -Non-caffeinated version of energy drink | ⬌ Wingate Peak Power ⬌ Wingate Average Power | |
Campbell et al. 2010 [101] | Recreationally active young men (n = 9) and women (n = 6) | -Energy drink with 2.1 mg/kg caffeine -Non-caffeinated version of energy drink | ⬌ Wingate Peak Power | ||
Hoffman et al. 2009 [102] | Male strength/power athletes (n = 12) | -Energy drink with 1.8 mg/kg caffeine -Non-caffeinated version of energy drink | ⬌ Wingate Power Performance | ||
Alford et al. 2001 [85] | Young adults (n = 36) | −250 mL Energy drink with 80 mg caffeine and 26 g CHO -Carbonated placebo -No drink | *↑ Maximum Speed on Cycle Ergometer | -26 g CHO | |
Campbell et al. 2016 [97] | College men (n = 8) and women (n = 11) | -37 mL Energy shot with 2.4 mg/kg caffeine -37 mL Placebo | ⬌ Repeated Sprint Speed | ||
Mood/ Reaction Time/ Alertness | Alford et al. 2001 [85] | Young adults (n = 36) | -250 mL Energy drink with 80 mg caffeine and 26 g CHO -Carbonated placebo -No drink | *↑ Choice Reaction Time *↑ Concentration *↑ Memory | -26 g CHO |
Walsh et al. 2010 [87] | Recreationally active men (n = 9) and women (n = 6) | -26 g Pre-workout with unknown amount of caffeine (ingredients listed in column 5) -Placebo | *↑ Focus and Energy in 1st 10 min of Exercise ⬌ Energy, Fatigue, and Focus Immediately Post-exercise | -2.05 g taurine, caffeine, and gluconolactone, 7.9 g L-leucine, L-isoleucine, L-valine, L-arginine and L-glutamine, 5 g of di-creatine citrate, and 2.5 g of βalanine | |
Hoffman et al. 2009 [102] | Male strength/power athletes (n = 12) | -Energy drink with 1.8 mg/kg caffeine -Non-caffeinated version of energy drink | *↓ Reaction Time *↑ Feelings of Energy and Focus NS↑ Alertness | ||
Seidl et al. 2000 [103] | Male (n = 4) and female (n = 6) graduate students | -Energy drink with 160 mg caffeine -Placebo | *↓ Reaction Time at Night ⬌ Vitality Scores at Night [[when compared to the Placebo Group who saw a significant decline in vitality and response time]] | 2.0 g taurine, 1.2 g glucuronolactone, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 microg vitamin B12 | |
Scholey et al. 2004 [104] | Healthy volunteers (n = 20) | -250 ml Energy drink with 75 mg caffeine -Non-caffeinated version of energy drink -Placebo | *↑ Secondary Memory *↑ Speed of Attention | −37.5 g glucose, ginseng, and Ginkgo biloba | |
Smit et al. 2004 [105] | Healthy volunteers (n = 271) | -Caffeine + CHO + Carbonation -Placebo with carbonation -Placebo without carbonation | ⬌ Mood and Performance (during fatiguing and cognitively demanding tasks) | -CHO | |
Rao et al. 2005 [106] | Healthy volunteers (n = 40) | -Caffeine + CHO -Placebo | *↑ Event Related Potentials in ECGs *↑ Behavioral Performance in Accuracy and Speed of Performance | -CHO | |
Howard et al. 2010 [107] | College students (n = 80) | -Energy drink with 1.8 ml/kg caffeine** -Energy drink with 3.6 ml/kg caffeine -Energy drink with 5.4 ml/kg caffeine -Non-caffeinated version of energy drink -No drink | Compared with the placebo and no drink conditions, the energy drink doses decreased reaction times on the behavioral control task, increased subjective ratings of stimulation and decreased ratings of mental fatigue. Greatest improvements in reaction times and subjective measures were observed with the lowest dose (1/8 mg/kg). | Taurine, sucrose and glucose, B-group vitamins | |
Wesnes et al. 2016 [108] | Young volunteers (n = 24) | -250 mL Energy drink with 80 mg caffeine + 27 g glucose -250 mL Energy drink with 80 mg caffeine -250 mL Placebo | *↑ Working and Episodic Memory | -27 g Glucose |