Does ergogenic effect of caffeine supplementation depend on CYP1A2 genotypes? A systematic review with meta-analysis.
Study Goal
The researchers aimed to evaluate the influence of the CYP1A2 gene variant (rs762551) on athletes' exercise performance after caffeine intake.
Results Summary
Caffeine improved cycling time trials in individuals with the A allele of CYP1A2 but not the C allele. It had no significant effect on Wingate or countermovement jump performance, regardless of genotype.
Population
Athletes (n = 666 participants)
Effective Dosage
Not specified
Duration
Acute intake (single dose)
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine intake | decrease | cycling time trial | participants | WMD = -0.48, 95%CI: -0.83 to -0.13, p = 0.007 | significantly improved | #1 |
acute caffeine intake | decrease | cycling time trial | individuals with the A allele | WMD = -0.90, 95%CI: -1.48 to -0.33, p = 0.002 | improved | #2 |
acute caffeine intake | no change | cycling time trial | individuals with the C allele | WMD = -0.08, 95%CI: -0.32 to 0.17, p = 0.53 | did not improve | #3 |
caffeine supplementation | no change | Wingate test performance | - | WMD = 8.07, 95%CI: -22.04 to 38.18, p = 0.60 | did not influence | #4 |
caffeine supplementation | no change | countermovement jump test (CMJ) performance | - | WMD = 1.17, 95%CI: -0.02 to 2.36, p = 0.05 | did not influence | #5 |
caffeine supplementation | decrease | cycling time trials | Participants with the CYP1A2 genotype with A allele | - | improved | #6 |
acute caffeine supplementation | no change | Wingate performance | - | - | failed to increase | #7 |
acute caffeine supplementation | no change | CMJ performance | - | - | failed to increase | #8 |
BACKGROUND: The ergogenic effects of caffeine intake on exercise performance are well-established, even if differences exist among individuals in response to caffeine intake. The genetic variation of a specific gene, human cytochrome P450 enzyme 1A2 (CYP1A2) (rs762551), may be one reason for this difference. This systematic review and meta-analysis aimed to comprehensively evaluate the influence of CYP1A2 gene types on athletes' exercise performance after caffeine intake. METHODS: A literature search through 4 databases (Web of Science, PubMed, Scopus, and China National Knowledge Infrastructure) was conducted until March 2023. The effect size was expressed as the weighted mean difference (WMD) by calculating fixed effects meta-analysis if heterogeneity was not significant (I RESULTS: The final number of studies meeting the inclusion criteria was 12 (n = 666 participants). The overall analysis showed that the cycling time trial significantly improved after caffeine intake (WMD = -0.48, 95% confidence interval (95%CI): -0.83 to -0.13, p = 0.007). In subgroup analyses, acute caffeine intake improved cycling time trial only in individuals with the A allele (WMD = -0.90, 95%CI: -1.48 to -0.33, p = 0.002), but not the C allele (WMD = -0.08, 95%CI: -0.32 to 0.17, p = 0.53). Caffeine supplementation did not influence the Wingate (WMD = 8.07, 95%CI: -22.04 to 38.18, p = 0.60) or countermovement jump test (CMJ) performance (WMD = 1.17, 95%CI: -0.02 to 2.36, p = 0.05), and these outcomes were not influenced by CYP1A2 genotype. CONCLUSION: Participants with the CYP1A2 genotype with A allele improved their cycling time trials after caffeine supplementation. However, compared to placebo, acute caffeine supplementation failed to increase the Wingate or CMJ performance, regardless of CYP1A2 genotype.