One way of judging RPE is to look at bar speed decay. As a general approach, a bit of slowdown is 7, more significant slowdown is 8, some grind is 9, lots of grind is 10. You could rate RPE by feel, then adjust by 0.5 or maybe more based on looking at video. Given individual differences, many lifts should be observed to get a good feel for this.
That’s one way that may be applicable for one particular lifter. People have various grinding abilities, and getting to know the lifter is important if you want to have an idea as to how they’re performing. Check out this guy for example:
This is why bar speed alone is an imperfect metric, why you can’t tell someone else what their RPE was, and why self-rated RPE has been described as “capturing more information”, including some “intangibles” compared to bar speed.
Bar speed can help you distinguish ~0.5 of an RPE, i.e. @8 vs @8.5. But it seems to work much better for people with solid, consistent form. If your form drifts around, or are still learning proper form, it is not as useful.
This is from personal experience with measuring my own bar speed.
Hi Austin, you inspired me: when someone is a grinder like this, how should they rate their RPE? I mean after a grinding rep, they don’t necessarily know how many more reps they still have in the tank. They might conclude it was a 9.5. However, it was a weight that they did 5 reps before and there is NO WAY one single rep be rated 9.5, so they pulled another 4 reps, legs shaking but in correct form (assuming). Now after this set of five, what should be the RPE this person allocates? Is there such a thing as a “natural grinder” who lifts anything above RPE 7 in a grinding fashion? Obviously just asking for a friend…
And what can one learn from bar speed variation for different reps in a set? Form issue? Or probably nothing is what you would say?
As I said above, you cannot tell someone else what their RPE is.
I have coached many lifters who are “natural grinders” like this, and they can still learn to rate it for themselves. I am quite confident that the lifter in that video didn’t pull the first rep and think “well, i have ZERO IDEA how many reps I’m going to pull here, so let’s just see what happens!”