Table 1.

Descriptive information for studies included in the meta-analysis.

Study	Study design	Sample size	Intervention/Exposure	Time of caffeine intake before the experimental session	Outcome assessment
Distelberg et al. (2017) the United States	RCT	49 Healthy participants	710 mL of either regular coffee (containing 450 mg caffeine) or decaffeinated coffee	5 day	BAI
Chtourou et al. (2019) Tunisia	RCT	19 Male physical-education students	Drinking 2 cans of “Red Bull’ beverage (containing 160 mg caffeine) or drinking a placebo	1 h	POMS
García et al. (2017) Colombia	RCT	80 Medical students	The intake of 460 mL of either an energy drink or carbonated water	1 h	STAI
Giles et al. (2017) the United States	RCT	96 Adults	Consuming 400 mg caffeine or placebo	45 or 75 min	STAI
Jin et al. (2016) Korea	CS	234 Middle school students	Daily coffee intake >27.5 mg or <4 mg	1 month	BAI
Papakonstantinou et al. (2016) Greece	RCT	40 Healthy individuals	Randomly consumed four 200 mL coffee beverages containing 160 mg caffeine	1 h	SAS
Quinlan et al. (1997) the United Kingdom	RCT	16 Habitual caffeine consumers	Subjects ingested caffeine dose or placebo	1 h	STAI
Souissi et al. (2012) Tunisia	RCT	12 Elite judoists	Beverages were ingested with/without 100 mg caffeine	1 h	POMS

BAI, beck anxiety inventory; POMS, profile of mood states; STAI, state-trait anxiety inventory; SAS, self-rating anxiety scale.