Hypertrophy
How close to failure should you train?
Effort is the part of training you cannot see on paper. Two people can do the same 3 sets of 10 and get very different results, because one stopped with 6 reps left and the other with 1. Here is where to stop a set.
Jeff Shaverian, fitness trainer and physical therapist · 3 min read · Reviewed October 2026
The short answer
0 to 3 reps left
For muscle growth, finish most working sets with 0 to 3 reps left in the tank. Stay 1 to 3 reps short on heavy squats, deadlifts and presses. Go closer to failure on machines and single-joint exercises, where a missed rep is safe.
Reps in reserve, explained
Reps in reserve (RIR) is how many more good reps you could have done when you stopped the set. Stop a set of 10 when you could have done 12, and that is 2 RIR. Many coaches pair it with a 1 to 10 effort scale (RPE): RPE 10 means no reps left, RPE 9 means one, RPE 8 means two.
| Reps in reserve | RPE | What it feels like |
|---|---|---|
| 0 | 10 | You could not do another good rep |
| 1 | 9 | One more, and only just |
| 2 | 8 | Two more, with the bar slowing down |
| 3 | 7 | Hard, but the bar still moves fast |
| 5 or more | 5 or less | A warm-up: good practice, little growth |
Why it matters for muscle
Muscle grows when the fibers doing the work are pushed hard. Near the end of a hard set, the bar slows and your body brings in more fibers to keep it moving. Stopping a set with many reps left skips most of that.
The research backs this up. A 2023 meta-analysis by Refalo and colleagues found that going all the way to failure gave about the same growth as stopping a little short, when the total work was the same. A 2024 analysis by Robinson and colleagues found that growth improved the closer sets got to failure, while strength gains depended on it much less. Close matters. Actual failure on every set is optional.
Most people stop too early
When lifters guess how many reps they have left and then keep going, they usually do more than they guessed, and beginners miss by the most. A set you think is 2 reps from failure is often 4 or 5 reps away.
You get better at judging with practice, and guesses get more accurate near the end of a set.
Try this
Calibrate your effort
Once a week, take the last set of a safe exercise, like a machine press or a dumbbell curl, to true failure. Before you start, guess how many reps you will get. The gap between your guess and the real number shows how far off your "2 reps left" really is.
Where failure costs more
Failing a rep on a leg extension costs you nothing. Failing a heavy squat or deadlift is different: technique breaks down in the last reps, the fatigue lasts longer, and a missed rep can be dangerous without a spotter or safety bars.
- Big barbell lifts (squat, deadlift, bench, overhead press): 1 to 3 reps in reserve. Stop when the bar slows sharply or your position changes.
- Dumbbells and cables: 0 to 2 reps in reserve.
- Machines and single-joint exercises (curls, extensions, raises): 0 to 1. These are the safest places to go to failure.
Technique comes first. If your form breaks before you reach your target, that is where the set ends. A rep that changes the movement is not a rep I count.
Quick questions
Is training to failure dangerous?
On machines and single-joint exercises, no. On heavy barbell lifts the risk goes up, because form breaks down in the last reps and a missed rep needs a spotter or safety bars. Stay 1 to 3 reps short there.
Should beginners train to failure?
Beginners grow quickly without it, and their first job is learning technique. Keep 2 to 3 reps in reserve on the big lifts, and use the occasional failure set on a machine to learn what hard really feels like.
Does it matter for strength?
Much less. Strength depends more on lifting heavy loads and practicing the lift than on how close each set gets to failure.
How I coach it
In sessions I watch bar speed and position, not just the rep count, and I tell you when there is more in the tank. Over a block, you learn what 2 reps in reserve actually feels like. That skill keeps paying off long after we stop training together.
About the author
Jeff Shaverian
Fitness Trainer and Physical Therapist · Da Nang · Phan Công Bình
I coach strength, muscle and fat loss in Da Nang, and I assess how you move, using the Kinesiopathological Model, before I load it. I have coached clients for seven years and worked in rehab for two, in English and Vietnamese.
Sources
- Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine. 2023;53(3):649-665.
- Robinson ZP, Pelland JC, Remmert JF, et al. Exploring the dose-response relationship between estimated resistance training proximity to failure, strength gain, and muscle hypertrophy: a series of meta-regressions. Sports Medicine. 2024.
- Halperin I, Malleron T, Har-Nir I, et al. Accuracy in predicting repetitions to task failure in resistance exercise: a scoping review and exploratory meta-analysis. Sports Medicine. 2022;52(2):377-390.
- Helms ER, Cronin J, Storey A, Zourdos MC. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal. 2016;38(4):42-49.
This article is general education, not medical advice. Reviewed October 2026.