Methodology
Caffeine and Training Performance
Francesco Zen, founder of ZTraining · Last updated June 20, 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, and that effect doesn't disappear once the immediate boost fades, it tends to leave you more tired afterward than you'd otherwise be. Worth factoring in, especially for anyone already managing cortisol and recovery carefully.
Related: Stress, cortisol and belly fat, what's real · Supplements that are a waste of money
Francesco Zen is the founder of ZTraining and ZLIFE, with 18 years of coaching experience working with executives across the UK, US, and UAE. He built Mr Z, an AI coach trained on his methodology to bring the same approach to a wider audience.