Table 2 Summary of studies that explored the effects of caffeine on exercise performance in the heat

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

Beaumont et al. 2017 [310, 367]

Recreationally active males (n = 8)

• 6 mg/kg caffeine

• Placebo

*↑ Endurance cycle performance in heat

*↓ RPE during initial 60 min of exercise