Does caffeine really improve performance?

Does caffeine improve performance?

Well … it depends, says a new study review.

In a recent meta-analysis of 16 randomized controlled trials, researchers looked at the effects of caffeine on exercise performance, based on the genetic differences of study participants. While the benefits of caffeine on general exercise performance is supported by the literature, studies have not necessairly shown that EVERYONE benefits from caffeine, with regards to performance, and that some people might even experience worse performance when they use it.

Scientists evaluated the potential for individual differences in responding to caffeine. It highlights the role of a specific gene in metabolizing caffeine, and how genetic variations in this gene can impact the ergogenic effects of caffeine.

Participants categorized as having “fast” or “intermediate” caffeine-metabolizing genes had an improved performance, but those with “slow” caffeine-metabolizing genes experienced a reduced performance.

All studies provided the participants with an acute dose of caffeine prior to exercise and reported at least one of the following outcomes related to exercise performance: total work done, average power output, average velocity, average height jumped, and time to completion (exercise performance) or time to exhaustion (exercise capacity).

In all of the studies, the reviewers highlighted teh role of a specific gene – CYP1A2 – in metabolizing caffeine, and how genetic variations in this gene can impact the ergogenic effects of the stimulant. The influence of caffeine dose and timing were also investigated.

Caffeine’s effect on exercise performance was evaluated separately for three single nucleotide polymorphisms (SNPs) of the CYP1A2 gene related to caffeine metabolism, namely:

  • AA: known as fast caffeine metabolizers
  • AC: known as intermediate caffeine metabolizers
  • CC: known as slow caffeine metabolizers

The findings suggest that people with different genotypes (AA, AC, and CC) may respond differently to caffeine intake, in terms of exercise performance. Studies have shown that AA carriers, considered “fast” metabolizers, may experience greater performance improvements with caffeine, while CC carriers, considered “slow” metabolizers, may even exhibit impaired performance. Some conflicting results have been observed in other studies, but the meta-analysis indicates that caffeine is ergogenic in AA carriers and may impair performance in CC carriers, with variable effects in AC carriers. The paper also discusses the influence of conflict of interest (COI) in the results of caffeine studies, and how it may impact the observed caffeine-genotype interaction on exercise performance.

Effect of dose

Higher doses of caffeine seemed to have more impact on positive performance in slow metabolizers (i.e., performance was worse with lower doses).

Effect of timing

For those who more slowly metabolized caffeine, having a longer time between caffeine ingestion and exercise was better for performance (i.e., performance was worse with shorter time between caffeine ingestion and exercise).

Neither dosage or timing seemed to have an effect on the fast metabolizers.

While it might be premature to recommend genetic profiling for athletes when it comes to caffeine, there is merit in understanding one’s genotype and exploring self-experimentation with caffeine dosing and timing. The paper emphasizes the need for more research in the field of nutrigenomics and advises individuals to enjoy caffeine-containing beverages as they prefer.

To read the entire paper, click here: https://pubmed.ncbi.nlm.nih.gov/37844569/

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