Wang et al. 2024, CYP1A2 genotype and caffeine ergogenic effect — systematic review & meta-analysis

Meta-analysis of 12 studies (666 participants) examining whether CYP1A2 genotype moderates caffeine’s ergogenic effect. Carriers of the A allele (fast metabolisers) improved cycling time-trial performance by roughly 5.8% after caffeine, while C-allele carriers gained only about 0.6% — a meaningful difference. The effect was not apparent for anaerobic or strength tasks. The review provides the strongest pooled evidence to date that the CYP1A2 question is settled for endurance cycling, though it remains less clear across all sport types. Moderate.