Table 2.

Variables obtained during the Wingate test and subjective perception of muscle power and exertion with the ingestion of 3 mg·kg⁻¹ of caffeine or a placebo for AA homozygotes and C-allele carriers.

Variable	Placebo	Caffeine	Mean Difference	95% IC for the Difference	p
Mean Power (W)	511 ± 113	521 ± 115 *	10	(5.3; 15.0)	0.000
AA homozygotes	494 ± 142	504 ± 140	9	(–0.9; 18.5)	0.120
C allele carriers	516 ± 107	527 ± 110 *	11	(4.6; 16.4)	0.002
Peak Power (W)	663 ± 143	680 ± 146 *	16	(3.7; 29.0)	0.014
AA homozygotes	637 ± 200	646 ± 201	9	(–0.9; 18.5)	0.065
C allele carriers	671 ± 128	690 ± 131 *	19	(1.9; 35.5)	0.031
Fatigue index (%)	44.2 ± 6.8	45.0 ± 7.2	0.8	(–2.0; 3.6)	0.571
AA homozygotes	42.3 ± 6.5	42.2 ± 6.7	–0.1	(–2.1; 1.8)	0.844
C allele carriers	44.8 ± 7.0	45.9 ± 7.3	1.1	(–2.7; 4.8)	0.555
Perceived power	6 ± 2	7 ± 2	1	(–0.3; 1.7)	0.158
AA homozygotes	6 ± 2	7 ± 2	1	(–2.6; 3.8)	0.634
C allele carriers	6 ± 2	7 ± 2	1	(–0.4; 1.9)	0.188
Perceived exertion	6 ± 2	6 ± 2	0	(–0.9; 1.1)	0.836
AA homozygotes	6 ± 1	6 ± 2	0	(–2.2; 3.0)	0.688
C allele carriers	6 ± 2	6 ± 2	0	(–1.2; 1.2)	1.000

Data are mean ± SD for 21 healthy participants: AA homozygotes (n = 5) and C-allele carriers (n = 16). (*) Different from placebo condition (p < 0.05).