What is RPE and should I use it?
RPE, or rate of perceived exertion, rates how hard a set felt from 1 to 10. It is optional in Kinoku, and you can turn it on for each set.
RPE stands for rate of perceived exertion, a score from 1 to 10 for how hard a set felt. A 10 means you could not have done one more rep. The info sheet in Kinoku links the top scores to reps in reserve (RIR), which is how many reps you think you had left. So a 9 means about one rep left, an 8 about two and a 7 about three, while a score below 7 reads as warm-up weight.
Both scores are optional, and a workout logs fine without them. To rate each set, turn on Per-Set RPE, or RIR (Reps in Reserve), in Settings under Per-Exercise Tracking. The same switches sit in Screen settings in the ⋮ menu of the exercise screen, so you can turn them on in the middle of a workout.
Whether to use it is up to you, but the number is only as good as your honest guess. Many lifters find it handy for spotting days when a usual weight feels heavier than normal. Others would rather log only weight and reps and keep each set quick.