The single biggest misconception about RPE training is that it is a training program, and it 100% is not. Just like Conjugate or DUP, it is a training principle, not a program. And in reality you could have a Conjugate DUP program that is RPE based. They are all just tools within programming.
So what is RPE? It is a subjective loading parameter. Percentages and weight on the bar are objective loading parameters, meaning exact numbers, but RPE is a subjective way to rate the load on the bar. 3×3 at 80% and 3×3 @ 6 RPE are essentially stating the same thing, so let me explain further. (If you are unfamiliar with RPE training in general, make sure to read What is RPE training? before reading on)
To go deeper into this, let’s say you have a 3×3 at 80%. You are stating the objective load at 80%. Going further, if your 1RM is 400lbs., then you are performing a 3×3 at 320lbs. Both of these mean the same exact thing, and when written in an “Instagram post”, they are relaying the objective difficulty and/or load of the set(s) being performed. There is one big issue in my opinion with that first example though of stating 3×3 at 80%. That issue is that 80% for a set of 3 is not the same for everyone, so it really isn’t stating the difficulty of that loading parameter in relation to you. There was actually a study done recently where trained participants performed an AMRAP with 70% of their 1RM on squats. The average number of reps completed was 15, but there was a range of 8 reps all the way to 25! The main correlating factor? Femur length. Shorter femurs tended to get more reps, longer femurs less reps. So at any given percentages, each individual will have a deviation in how many reps they can perform.
So how does this relate to RPE? If we use the example of 3×3 at 80%, the majority of people can get about 7 to 8 reps with 80% of their 1RM. So this could very well be written as 3×3 @ 6 RPE. It means in sense the same thing. But the difference with those two programming methods is that if I give you 3×3 at 80%, that gives you a set number that I am using based on the average person and the average difficulty of 80%. But what if you don’t fit into that category? What if you could perform 10 to 12 reps with 80% of your 1RM, or maybe you are on the opposite end of the spectrum and you could only get 5 reps with 80%? Then that 80% means something different than what was intended.
That is where RPE is used as a subjective loading parameter. For the average person, 3×3 at a 6 RPE will be 3×3 at 80%. But for the examples of those outliers, or maybe on a day where you may feel weaker or stronger than normal, the 3×3 at a 6 RPE allows for variable loading parameters to adjust for individual differences and is why it has become a popular tool in modern day programming. Even if you haven’t used RPE intentionally as a tool in your programming, the fact is unintentionally you have. Let’s say you performed that 3×3 at 80% and you wrote in your “Instagram post” that you smoked it and it was super easy. With that thought process you are subjectively rating the difficulty of that set. The only difference between that and RPE, is that RPE is giving a set subjective parameter to describe the difficulty.
What it comes down to is whether you have 3×3 at 80%, 3×3 at 320lbs., or 3×3 @ 6 RPE, all 3 are in reality the same and all 3 are just different ways of writing the same loading parameter. 2 of those being objective and set, 1 being subjective and variable. There is a time and place for both. All of these principles are just tools for progression in strength and the application is based on individual preference and need.