RPE is commonly used metric to measure the intensity of an exercise. It is a subjective measure, meaning it is based on one's feeling/perception of the exercise/task at hand and how hard they feel like their body is working. This is the opposite of an objective measure such as heart rate that is influenced by physiological factors independent of your own personal feeling/perception (although the scale can surely correlate what is happening with heart rate).
HOW TO USE RPE
The scale has been modified to include a 1-10 range of intensity with 1 being lowest intensity and 10 being the highest. The table below gives you a good reference of each intensity level and how to grade them. For most healthy individuals, we should be aiming to exercise at a RPE of 4 or above depending on the desired stimulus.
The chart above is a great reference to use during cardiovascular exercise and HIIT, but we can also use the RPE scale with weightlifting. As you can see from the chart below, RPE can be converted into reps in reserve (RIR). RIR is a number value indicating how many more reps you would have in you before you hit failure.
For example, if the program calls for strict press x5 reps at an RPE of 8, you should use a weight that feels like you could only complete ~7 reps with (5 reps as programmed + the 2 RIR from RPE 8 as outlined in the chart below).
WHY USE RPE
RPE (and RIR) is a great metric to implement in exercise programs for purposes of individual autoregulation, being that everyone's response to exercise is a little bit different. It allows for more appropriate loading/intensity across a wide group of people with less risk of overtraining or undertraining them.
Written by: Marissa Oxenford, PT, DPT, CMFA-cert, CF-L1 Trainer, CPT