A new randomized crossover trial found that a pre-workout-sized dose of caffeine (6 mg/kg) raised markers of arterial stiffness within 2.5 hours. Adding a beetroot powder with 400 mg of nitrate brought those markers back to placebo levels. Blood pressure and endothelial function did not change, so this is a subtle effect rather than a red flag. The study involved just 24 healthy young adults and a single dose, leaving big questions about long-term use and older or hypertensive people. Here is what the data show, what they do not, and how to think about it if you rely on caffeine before training.
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