Two different meanings of intensity
In the gym, people use "intensity" two ways: how heavy the weight is (percent of your one rep max), and how hard you push the set (how close to failure you go).
Confusing the two causes problems. A light weight taken to failure can be brutal. A heavy weight stopped early can feel easy. Both matter, but separately.
Setting load (percent of 1RM)
- Strength work: 80-95 percent of your 1RM, for 1-5 reps.
- Muscle-building work: 60-80 percent of your 1RM, for 6-15 reps.
- You do not need to test a true max to estimate this — a weight you can do for 5 hard reps is roughly 85 percent, for 10 hard reps is roughly 75 percent.
Setting effort (RIR and RPE)
RIR means "reps in reserve" — how many more reps you could have done. RPE is a similar 1-10 scale of effort, where 10 is a true maximal effort.
Most working sets should land at 1-3 RIR: hard, but with a rep or two left if you needed it.
Why not every set should hit failure
- Training to failure on every set increases fatigue and soreness without adding much extra muscle or strength compared with stopping 1-2 reps short.
- Failure sets take longer to recover from, which can cut into your next session's quality.
- Save true failure for occasional top sets or the last set of an exercise, not every set of every session.
- If your performance is dropping session to session, you are probably running effort too high too often.