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.

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?

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.