Methodology
Caffeine and Training Performance
Francesco Zen, founder of ZTraining · Last updated 20 June 2026
What caffeine actually does in a session
The boost people feel during training is a perception and focus effect, not a genuine physical performance enhancement. It changes how the effort feels, not what the body is actually capable of.
The cost on the other side
Caffeine raises cortisol, most of all in people who rarely drink it, and as the boost fades it can leave you more tired than you would otherwise be. Worth factoring in, especially for anyone already managing cortisol and recovery carefully.
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He built Mr Z, an AI coach trained on his methodology to bring the same approach to a wider audience.