Table 1.

Participant characteristics

	ADORA2A		CYP1A2
	‘High’	‘Low’	‘Fast’	‘Slow’
Male	7	5	7	5
Female	4	2	3	3
Age (years)	23 ± 4	24 ± 5	23 ± 3	25 ± 5
Body mass (kg)	67.8 ± 10.5	75.3 ± 7.1	68.1 ± 11.0	73.9 ± 7.7
Height (m)#	1.72 ± 0.10	1.80 ± 0.05	1.73 ± 0.11	1.78 ± 0.04
BMI (kg m−2)	22.8 ± 2.3	23.1 ± 1.6	22.6 ± 2.3	23.4 ± 1.6
$\dot{V}{\text{O}}_{\text{2max}}$ (mL kg−1 min−1)	46.8 ± 10.4	48.4 ± 6.8	48.5 ± 6.3	46.2 ± 11.9
Wmax (W)	269 ± 81	293 ± 33	271 ± 53	287 ± 83
Caffeine intake (mg day−1)	143 ± 139	104 ± 126	121 ± 128	135 ± 145
[Low, moderate, high]	[7, 2, 2]	[6, 0, 1]	[7, 2, 1]	[6, 0, 2]

Participants are categorised according to ADORA2A (‘high’ or ‘low’ sensitivity) and CYP1A2 genotypes (‘fast’ or ‘slow’ metaboliser)

BMI body mass index, $\dot{V}{\text{O}}_{\text{2max}}$ maximal oxygen uptake, W_max maximal test workload. Low, moderate, and high caffeine intake: 0–150, 151–300, and > 300 mg day⁻¹, respectively. Data are mean ± SD, and n for sex and caffeine intake categories

^#P < 0.05, ‘high’ vs. ‘low’ sensitivity