I recommend everybody just uses caffeine as a PED. Mostly off it in training so race day hits.

Caffeine is the most studied performance aid in endurance sport, and it was on the banned list until 2004. That fact alone should tell you how well it works. Now it is legal, cheap, and sitting in every gas station cooler, and most runners still use it wrong.

The evidence-backed dose is 3 to 6 milligrams per kilogram of body weight about an hour before the effort. Not a sip of coffee at breakfast. A measured dose, timed. The ISSN position stand puts the endurance benefit on repeat across dozens of trials, heat included.

The part I actually coach is the other six days. I stay mostly off caffeine in training, maybe 100 milligrams once a week. Habitual intake blunts the edge. Save it and race day feels like someone else is pushing.

And it does not have to be complicated. Sometimes my dose at mile 45 is a flat Coke at an aid station. The molecule does not care how fancy the container is.