Training intensity
Bodybuilding intensity measures the difficulty of the effort. Find out how to calculate it with % of 1RM, RPE, and RIR.
Training intensity
Definition
Intensity in strength training measures the difficulty of the effort relative to your maximum capacity. It's one of the 3 pillars of programming, alongside volume and frequency.
Important: in strength training, intensity does NOT mean "hard session" or "short but exhausting workout." It's a precise technical term.
💡 Intensity can be measured 3 ways: as % of 1RM, via RPE (perceived exertion), or RIR (reps in reserve).
The 3 measurement methods
1. Percentage of 1RM
Classic method. You calculate your load as a percentage of your 1-rep max.
| % of 1RM | Possible reps | Effort type |
|---|---|---|
| 95-100% | 1-2 | Max strength |
| 85-95% | 3-6 | Strength |
| 70-85% | 6-12 | Hypertrophy |
| 60-70% | 12-20 | Muscular endurance |
| < 60% | 20+ | Endurance |
2. RPE (Rate of Perceived Exertion)
Subjective scale from 1 to 10 measuring effort at end of set.
- RPE 10: absolute failure, impossible to do 1 more rep
- RPE 9: 1 rep in reserve
- RPE 8: 2 reps in reserve
- RPE 7: 3 reps in reserve
- RPE 6: 4 reps in reserve
3. RIR (Reps In Reserve)
RPE variant: how many reps you could still do in good form. RIR 2 = 2 reps left before failure.
What intensity for which goal?
| Goal | % 1RM | RIR |
|---|---|---|
| Max strength | 85-95% | 1-3 |
| Hypertrophy | 65-85% | 0-3 |
| Muscular endurance | 50-65% | 0-2 |
| Active recovery | 40-50% | 5+ |
The myth of systematic failure
For years, going to failure on every set was thought necessary for hypertrophy. Modern science strongly nuances this.
- ✅ Going to failure occasionally (1-2 sets at the end of an exercise): useful
- ❌ Going to failure on every set: too much fatigue, degrades technique
- ✅ Working at RIR 0-3 on most sets: optimal
⚠️ Systematic failure on heavy compound exercises (squat, deadlift) significantly increases injury risk.
How to progress on intensity
Several levers:
- ✅ Increase load at equal reps
- ✅ Reduce RIR (from 3 to 2 to 1)
- ✅ Increase eccentric tempo (slower descent)
- ✅ Reduce rest times (higher density)
- ✅ Intensification techniques (drop sets, rest-pause)
Common mistakes
- ❌ Confusing intensity (% 1RM) with perceived intensity (RPE)
- ❌ Going to failure on every set of the session
- ❌ Stopping too far from failure (RIR 5+) thinking it's enough
- ❌ Not adapting intensity to exercise type (failure ok in isolation, dangerous in heavy compound)
- ❌ Testing 1RM too often
Key takeaways
Intensity is the qualitative training lever. Working at RIR 0-3 on most sets ensures sufficient stimulus without overtraining. For hypertrophy: 65-85% 1RM. For strength: 85-95%. Well-dosed intensity + coherent volume = the formula for progress.
Termes associés
1RM is the maximum weight you can lift for one rep. Reference for calculating % and planning your strength training.
RPE (Rate of Perceived Exertion) is a 1-10 subjective scale to measure the intensity of your effort during training.
Training volume represents the total amount of work performed. 12-20 sets per muscle per week for steady progression.
RIR (Reps in Reserve) measures how many reps you have left before muscular failure. Key tool for managing intensity.
