Training to Failure: How Close Natural Lifters Should Go

Effort is the part of training you control every single set. Too easy, and the set does little. Too hard on every lift, and fatigue eats into the next session. Natural lifters grow best in the zone between those two errors.

This guide shows you what the research says about failure, how to measure effort with RIR and RPE, and where to place true failure in your week.

What the failure research actually shows

Three lines of evidence point the same way. Sets taken close to failure build muscle well. Going all the way to failure adds little, and it costs more recovery.

The 2022 and 2023 meta-analyses

A 2022 meta-analysis of 15 studies compared failure and non-failure training (Grgic et al., 2022). It found no significant difference for strength or hypertrophy overall. In the subgroup of resistance-trained lifters, failure showed a small advantage for muscle size.

A 2023 meta-analysis by Refalo and colleagues reached a similar answer. It also tested velocity loss, a proxy for how close sets get to failure, and found no advantage for high (over 25%) versus moderate (20–25%) velocity loss thresholds.

"Overall, our main findings suggest that (i) there is no evidence to support that resistance training performed to momentary muscular failure is superior to non-failure resistance training for muscle hypertrophy and (ii) higher velocity loss thresholds, and theoretically closer proximities-to-failure do not always elicit greater muscle hypertrophy."

Refalo, Helms, Trexler, Hamilton and Fyfe, Sports Medicine (2023), Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy

Closer is better, up to a point

A 2024 series of meta-regressions estimated reps in reserve for each study (Robinson et al., 2024). Muscle growth improved as sets ended closer to failure. Strength gains were similar across a wide range of effort.

So effort matters for hypertrophy. The gap between 1–2 reps in reserve and true failure is small, though. A study in trained lifters found similar quadriceps growth over 8 weeks whether sets went to failure or stopped at 1–2 reps in reserve (Refalo et al., 2024). The failure sets also caused more acute fatigue.

RIR and RPE: how to measure effort

Reps in reserve (RIR) is the number of clean reps you could still do at the end of a set. The RIR-based RPE scale turns that into a score: RPE 10 means 0 RIR, RPE 9 means 1 RIR, and so on. The scale was tested in squatters lifting single reps at 60, 75, and 90% of 1RM (Zourdos et al., 2016).

RPE	RIR	What it feels like
10	0	No more reps possible with good form
9	1	One more rep, maybe
8	2	Two more reps, sure of it
7	3	Bar speed still fast, clearly more left
6 or less	4+	Warm-up or technique work

Calibrate your estimates

Many lifters misjudge how many reps they have left, especially on high-rep sets. Fix that with a few test sets.

1. Pick a safe exercise, such as a machine press or leg press.
2. Before the set, predict your RIR at a target rep count.
3. Do the target reps, then keep going to failure.
4. Compare the extra reps you did with your prediction.

Repeat this every few weeks. Your RIR calls get sharper, and your training effort becomes more precise.

How close natural lifters should train

Use these default targets. They fit most natural lifters on most programs.

• Heavy compound lifts (squat, deadlift, bench, rows): RPE 7–9, or 1–3 RIR. Heavy failure on these lifts carries the most fatigue and form risk.
• Machine and cable compounds (leg press, hack squat, chest press): RPE 8–9, or 1–2 RIR. The last set can go to RPE 9–10.
• Isolation lifts (curls, raises, extensions, leg curls): RPE 9–10. Failure on the last set is low cost and a good fit here.
• Higher-rep sets (15–30 reps): go closer to failure. Your RIR estimate is least accurate in this range, so push a bit past where you think you should stop.

A natural lifter's main limit is recovery between sessions. Effort that leaves you able to beat your logbook next week beats effort that wipes you out today.

Where failure fits in your week

Think of failure as a tool with a fixed budget. Spend it where it pays and where it costs little.

Put failure last

Use failure on the final set of an exercise, and on the last exercises of a session. A failure set early in the session lowers performance on every set that follows.

Match failure to the exercise

Use failure on stable, low-skill movements where a missed rep is safe. Keep it off heavy barbell squats and deadlifts, where form breaks down before the muscle does.

Plan your effort across the block

Start a block at RPE 7–8 on most sets. Move toward RPE 8–9 as the weeks go on. Use failure sets in the final hard week before a lighter week. That lighter week then clears the fatigue you built.

A sample effort plan for one upper day

Exercise	Sets x reps	Effort
Bench press	3x6–8	RPE 8 (2 RIR)
Chest-supported row	3x8–10	RPE 8–9
Machine shoulder press	3x10–12	RPE 9, last set RPE 10
Cable lateral raise	3x12–15	Last set to failure
EZ-bar curl	2x10–12	Last set to failure
Triceps pressdown	2x12–15	Last set to failure

Rest 2–3 minutes on the first two lifts and 60–90 seconds on the rest. Add reps within the range before you add load.

Signs you are pushing too hard or too easy

Use your logbook as the judge.

• Too easy: your reps and loads climb every session with no effort, and your RIR calls are often off by 4 or more.
• Too hard: your rep records fall for two weeks in a row, joints ache, or sleep worsens.
• About right: you add a rep or a small amount of load on most lifts over each block.

Build it in the free builder

Put your effort targets into the plan itself. Open the free program builder and enter your training days per week and the lifts your equipment allows. For each lift, set sets x reps and an RPE target, then mark the last isolation sets as failure sets.

Want a ready start? Open the starter programs and load the four-week foundation block. Raise the RPE targets a little each week, and save your failure sets for the final hard week.