Sometimes training off your heart rate can be misleading… If you’re fatigued, dehydrated, stressed, or training in the heat, your heart rate can climb or lag independent of actual effort. In those scenarios, there’s a good chance the data isn’t accurately representing your output - and your heart rate data is wrong. That’s where RPE comes in. RPE - Rate of Perceived Exertion - is simply a way of asking, “How hard does this actually feel?” Not what your watch says. Not what the pace says. What does the effort feel like in your body? Because heart rate measures a response. RPE measures the experience. Your heart rate can drift because you didn’t sleep well. It can spike because you’re stressed. It can stay suppressed when you’re carrying fatigue. But RPE takes all of that into account automatically. It reflects breathing, muscle fatigue, mental strain, and overall readiness in one simple question. And the more you train with it, the more accurate it becomes. You learn what a true e...