When describing intensity of workout or other physical activity, the Rated Perceived Exertion (or RPE) scale is frequently used. RPE scale rates your subjectively perceived effort based on how you feel during a continuous activity:
0 – No activity. For example, sitting and reading this text.
1 – Barely noticeable.
2 – Extremely light.
3 – Light. Normally, efforts 0 to 3 are never used in workout descriptions.
4 – Easy. Somewhat like brisk walk or light jog for runner.
5 – Recovery. An easy jog. In Talk Test (sometimes used to define exercise intensity) terms, you can easily keep a conversation in this effort.
6 – Moderate. Some call it forever pace. You can talk sentences in this effort zone.
7 – Comfortably hard. For runner, it’s the fastest pace which can still be fun. You can say a sentence, but may need to take an occasional break.
8 – Hard. Your breathing is heavy, but you’re confident you can go faster. You can say a couple of words at a time, but you need a good reason to.
9 – Uncomfortably hard. If you take talk test, most words you say begin with f.
10 – Maximal effort. In talk test, you do not talk and hate the world.
This scale is universal and does not depend on athlete’s abilities, so using it in workouts makes them accessible to runners of all shapes and sizes.