Rate of Perceived Exertion (RPE)
RPE (Rate of Perceived Exertion) is a simple scale for how hard an effort feels to you, usually from 1 to 10. It makes training by feel concrete and works without sensors — a full signal alongside pace, power and heart rate.
What is RPE?
The thinking behind it: your body bundles everything that makes an effort hard — breathing, muscle fatigue, heat, daily form — into one feeling, and that feeling is surprisingly reliable. On a 1–10 scale a 3–4 is easy and long to sustain, a 6 is hard but controlled, and 8–9 is very hard and only holdable briefly. A 10 is all-or-nothing.
RPE has two big advantages: it works anytime and anywhere, even without a watch or power meter, and it captures what sensors miss. On a bad day the same pace feels harder — and that is relevant information. The drawback is that it’s subjective and takes practice: beginners under- or overestimate their numbers more often.
How do you use RPE?
Give your RPE for the session as a whole, shortly after finishing, and be honest — the scale only works if you don’t fill it in to suit yourself. Use it both to steer (a recovery day should be low) and to check: if an easy endurance run still felt like a 7, that says something about your recovery.
In strength training there is a related measure, RIR (reps in reserve): the number of reps you had left at the end of a set. Two in the tank corresponds roughly to RPE 8. That way you translate feel into the weights you choose too.
How Trimetra personalises this
Trimetra combines your RPE with sport, duration, structure and available sensor data instead of looking at it in isolation. The app also learns your personal calibration: if you consistently give higher or lower numbers than the session design expects, the app corrects for that offset — so that "a 6 from you" really is a 6 from you.
Frequently asked questions
What does RPE 6 mean?
On the 1–10 scale a 6 is firm but composed: you are clearly working, but keeping it under control. For comparison: 3–4 is easy and sustainable for a long time, 8–9 is very hard and only briefly sustainable, and 10 is all-out.
Is training by feel reliable?
Surprisingly reliable — your body bundles breathing, muscle fatigue, heat and daily form into one feeling, and that captures exactly what sensors miss. It does take practice: beginners over- or underestimate their scores more often. Be honest about what you enter.
What is RIR in strength training?
RIR (reps in reserve) is the number of repetitions you had left at the end of a set. It is the strength counterpart of RPE: two reps in reserve corresponds roughly to RPE 8. That is how you translate feel into the weights you choose.
Every term at a glance in the full glossary.