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Caffeine’s effect on endurance exercise performance may depend on the genes you wear

A small change in a single gene can make a big impact on caffeine's ergogenic effects on endurance exercise.

Study under review: Caffeine, CYP1A2 genotype, and endurance performance in athletes

Introduction

Caffeine is recommended for[1] and used by athletes[2] because of its performance-enhancing effects, especially when it comes to endurance exercise performance. But not everyone benefits, and not all studies[3][4] report significant improvements in endurance exercise performance. For instance, one small study[5] reported individual improvements ranging from 5% to 87% for running and 10% to 156% for cycling.

While some of the inconsistencies across studies may be due to differences in study design, participants, and caffeine dosage, another more pervasive and less obvious culprit is interindividual differences in caffeine metabolism.

Caffeine is almost completely metabolized by cytochrome P450 1A2 (CYP1A2)[6], a liver enzyme encoded by the CYP1A2 gene[7] that is known to process drugs and toxins. A single nucleotide difference[8] at a specific location (rs762551) in the gene can change the enzyme’s effectiveness, granting individuals with an AA genotype faster caffeine metabolism than CC or AC genotype carriers.

Who and what was studied?

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What were the findings?

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What does the study really tell us?

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The big picture

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Frequently asked questions

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What should I know?

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Other Articles in Issue #44 (June 2018)