Rate of Perceived Exertion Scale: Why RPE Is The Best Running Metric

No matter how good your GPS device is, it can’t tell you how you’re feeling – what your level of motivation, willpower, or muscle fatigue is on any given day. RPE does.

It also stops you from being too prescriptive in the pace you’re running; some days will be better or worse than others, and constantly trying to hit the same time or speed is often counterproductive.