Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes

source extracted confidence: high 2026-04-09
#adult #caffeine #cytochrome-p-450-cyp1a2 #double-blind-method #exercise-test

Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes

Guest et al., 2018 | Med Sci Sports Exerc | Rct

Citation

Guest Nanci, Corey Paul, ... El-Sohemy Ahmed. Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes. Med Sci Sports Exerc. 2018-Aug;50(8):1570-1578. doi:10.1249/MSS.0000000000001596

Abstract

PURPOSE: Many studies have examined the effect of caffeine on exercise performance, but findings have not always been consistent. The objective of this study was to determine whether variation in the CYP1A2 gene, which affects caffeine metabolism, modifies the ergogenic effects of caffeine in a 10-km cycling time trial. METHODS: Competitive male athletes (n = 101; age = 25 ± 4 yr) completed the time trial under three conditions: 0, 2, or 4 mg of caffeine per kilogram body mass, using a split-plot randomized, double-blinded, placebo-controlled design. DNA was isolated from saliva and genotyped for the -163A > C polymorphism in the CYP1A2 gene (rs762551). RESULTS: Overall, 4 mg·kg caffeine decreased cycling time by 3% (mean ± SEM) versus placebo (17.6 ± 0.1 vs 18.1 ± 0.1 min, P = 0.01). However, a significant (P <0.0001) caffeine-gene interaction was observed. Among those with the AA genotype, cycling time decreased by 4.8% at 2 mg·kg (17.0 ± 0.3 vs 17.8 ± 0.4 min, P = 0.0005) and by 6.8% at 4 mg·kg (16.6 ± 0.3 vs 17.8 ± 0.4 min, P < 0.0001). In those with the CC genotype, 4 mg·kg increased cycling time by 13.7% versus placebo (20.8 ± 0.8 vs 18.3 ± 0.5 min, P = 0.04). No effects were observed among those with the AC genotype. CONCLUSION: Our findings show that both 2 and 4 mg·kg caffeine improve 10-km cycling time, but only in those with the AA genotype. Caffeine had no effect in those with the AC genotype and diminished performance at 4 mg·kg in those with the CC genotype. CYP1A2 genotype should be considered when deciding whether an athlete should use caffeine for enhancing endurance performance.

Key Findings

Overall, 4 mg·kg caffeine decreased cycling time by 3% (mean ± SEM) versus placebo (17.6 ± 0.1 vs 18.1 ± 0.1 min, P = 0.01). However, a significant (P <0.0001) caffeine-gene interaction was observed. Among those with the AA genotype, cycling time decreased by 4.8% at 2 mg·kg (17.0 ± 0.3 vs 17.8 ± 0.4 min, P = 0.0005) and by 6.8% at 4 mg·kg (16.6 ± 0.3 vs 17.8 ± 0.4 min, P < 0.0001). In those with the CC genotype, 4 mg·kg increased cycling time by 13.7% versus placebo (20.8 ± 0.8 vs 18.3 ± 0.5 mi

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size 101
Age Range See abstract
Condition See abstract

MeSH Terms

  • Adult
  • Caffeine
  • Cytochrome P-450 CYP1A2
  • Double-Blind Method
  • Exercise Test
  • Genotype
  • Heart Rate
  • Humans
  • Male
  • Perception
  • Physical Endurance
  • Physical Exertion
  • Polymorphism, Single Nucleotide
  • Young Adult

Evidence Classification

  • Level: Rct
  • Publication Types: Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, Non-U.S. Gov't
  • Vertical: caffeine

Provenance

Source extracted via PubMed E-utilities API on 2026-04-10