RPE and reps in reserve: how hard each set should feel

Reps in reserve and RPE

RIR is how many more good reps you could have done. The lifting RPE scale is built on it: RPE 10 is no reps left, 9 is one, 8 is two, 7 is three, and 5 to 6 means four to six left.

Sources 1, 2

How hard sets should be

Big compound lifts at 2 to 3 reps in reserve (RPE 7 to 8), the last set of small isolation moves at 0 to 2, and 3 or 4 in reserve while you learn, as our plans say. The ACSM (American College of Sports Medicine) says sets near failure or at 2 to 3 reps in reserve are enough, and that exact targets aren't established.

Source 3

Failure isn't needed

Two meta-analyses of 15 studies each found no clear advantage for strength or muscle from training to failure. Exploratory analyses suggest muscle growth rises a little as sets end closer to failure, while strength doesn't.

Sources 4, 5, 6

Most people are about one rep out

In 12 studies with 414 people, most underestimated the reps they had left by about one on average, so they stopped a little further from failure than they thought. Judgements were better near failure, in later sets and in sets of 12 reps or fewer.

Source 7

Experience and practice

In the meta-analysis, training experience didn't change accuracy. Practice may help: in a small study, calling out your reps in reserve and then carrying on to check cut the average error by up to 2.3 reps over six weekly sessions, in younger and older adults.

Sources 7, 8

Cardio RPE is a different scale

For cardio, RPE usually means a 0 to 10 scale, where moderate is 5 or 6 and vigorous 7 or 8, or Borg's 6 to 20 scale. RPE 8 in the gym (2 reps left) is not the same as 8 out of 10 on a run.

Sources 9, 10, 11

Reps in reserve (RIR)

How many more good reps you could have done when you stopped the set. 2 RIR means you stopped 2 reps short of failure: the point where you can't complete another rep with good form.

Sources 2, 3

The lifting RPE scale

Published in 2016, it ties each number to the reps you had left:

• 10: maximum effort, no reps left.
• 9: one rep left.
• 8: two reps left.
• 7: three reps left.
• 5 to 6: four to six reps left.
• 3 to 4: light effort.
• 1 to 2: little to no effort.

Sources 1, 2

Two ends of the same thing

From RPE 7 to 10, RPE is 10 minus your reps in reserve: 2 RIR is RPE 8. Below 7, the scale uses ranges and feelings instead, because reps far from failure are hard to judge.

Sources 1, 2

Half-points

Some coaches use half-points such as 8.5. They aren't in the published scale, and since most people are about a rep out, they're finer than most of us can judge.

Sources 1, 2, 7

Session RPE

One rating for a whole session, multiplied by its minutes, gives a training load score for tracking how hard your training has been.

Source 12

Reps done plus reps left

Our one-rep max calculator takes the weight, the reps you did and the reps you had left, and estimates your maximum from a normal set.

Your first two weeks, or a new move

3 to 4 reps in reserve (RPE 6 to 7), as our plans start. You're still learning the move, and most people misjudge by about a rep.

Source 7

Big compound lifts

Squats, deadlifts, presses, rows and pulldowns: 2 to 3 reps in reserve (RPE 7 to 8). Our intermediate plans allow 1 to 3 (RPE 7 to 9).

Sources 3, 4, 5

The last set of small moves

Curls, raises, pushdowns and calf raises: 0 to 2 in reserve (RPE 8 to 10), as our plans allow. Growth may rise a little closer to failure: in 42 trained adults, single sets to failure grew some muscles slightly more than sets stopped 2 short, with no difference in strength.

Sources 6, 13

Drop sets and rest-pause

0 to 1 in reserve on each part (our editorial target): these methods work by going close to failure, so keep them to safe moves.

Source 14

Lighter weeks

4 or more in reserve (RPE 6 or less), as our plans' lighter weeks say; most athletes in a survey cut their effort in deload weeks.

Source 15

Warm-up sets

Well short of failure, about RPE 3 to 5 (our editorial target).

Source 2

Older lifters, or high blood pressure

2 to 3 in reserve, without going to failure. The ACSM says failure may be unwise for older people, and blood pressure rises steeply near failure, especially with a held breath.

Sources 3, 16, 17

About a rep out, on averageEmerging evidence

In 12 studies with 414 people, people underpredicted the reps they had left by 0.95 on average, so they had a little more in the tank than they thought. Results varied a lot between studies.

Source 7

Better near failure and in shorter setsEmerging evidence

Predictions were better closer to failure, in later sets and in sets of 12 reps or fewer; long, light sets were the hardest to judge. In 58 men and women on machine moves and rows, the same pattern held.

Sources 7, 18

Experience and practiceEmerging evidence

In the meta-analysis, training experience didn't change accuracy, and newer studies of men and women on machines, the bench press and the squat found the same. One study of 141 trainees found a tendency to improve with experience.

Practice may help, though the studies are small. In 26 younger and older adults, with no comparison group, calling out reps in reserve during sets taken to failure cut the average error by up to 2.3 reps over six weekly sessions, and accuracy improved over 8 weeks in another trial. In two small trials of trained men, it didn't improve over 6 weeks.

Sources 7, 18, 19, 20, 21, 8, 13, 22, 23

Trained lifters close to failureEmerging evidence

Trained men and women judging 1 or 3 reps in reserve on the bench press, with about 75% of their one-rep max, were within about two-thirds of a rep on average, whatever their sex, experience or strength.

Source 19

Older adultsEmerging evidence

In 25 adults aged about 68, predictions at 2 and 4 reps in reserve were about 2 reps out, while 6 in reserve was accurate, and their RPE ratings barely differed between the three sets (8.0, 7.6 and 7.3). With practice, older adults improved as much as younger ones in another small study.

Sources 24, 8

Experienced lifters rate a true maximum betterEmerging evidence

At a true one-rep max, experienced lifters gave ratings closer to 10 than novices: 9.8 against 9.0 in the squat, and 9.86 against 9.35 on the bench press. Ratings also tracked bar speed closely, because each rep slows as a set nears failure.

Sources 1, 25

Check before you rely on itEmerging evidence

An expert review advises beginners to record their reps in reserve alongside their training, and to check their accuracy with a set to failure at the same weight before basing loads on it.

Source 2

RPE tracks effortEmerging evidence

Across 75 studies, RPE ratings tracked how hard resistance exercise was, whatever people's sex, age or training, though results varied a lot between studies.

Source 26

RPE-based against percentage-based loadingEmerging evidence

In 21 trained men, setting loads by RPE worked as well as fixed percentages of a one-rep max, with a probable small edge for strength. Across 6 studies, adjusting loads on the day gave similar strength gains to fixed percentages.

Sources 27, 28

The ACSM's viewStrong evidence

The ACSM found too little evidence to say whether adjusting loads within a session changes strength or muscle.

Source 3

What to do

For most people, our plans' double progression with a reps in reserve target is enough. RPE charts and percentages suit people chasing a maximal lift; our one-rep max calculator works with them.

Bar-speed trackersMixed evidence

In 46 trained people, a bar-speed model built for each person predicted squat reps in reserve to within 2 reps on average, but general models did worse. In the hex bar deadlift, bar-speed predictions lacked accuracy, and in another study bar speed explained only about 30% of the reps people felt they had left. A tracker doesn't replace learning to judge it yourself.

Sources 29, 30, 31, 32

The 0 to 10 scale

Health guidelines rate effort from 0 to 10 relative to your own fitness: light activity is about 2 to 4, moderate 5 or 6, and vigorous 7 or 8.

Sources 9, 10

The talk test

A cross-check: in moderate activity you can talk but not sing; in vigorous activity you can't say more than a few words without pausing for breath.

Sources 33, 10

The Borg scale

The Borg scale rates effort from 6 (no exertion at all) to 20 (the hardest you could manage). It was designed so that your rating times 10 roughly matches your heart rate, but treat that as a rough guide. Our heart disease guide explains how cardiac rehab uses it, what the numbers in between feel like, and the range rehab works at.

Sources 11, 34

The same number, different meanings

RPE 8 in the gym means about 2 reps left; 8 out of 10 on a run is vigorous; and on the Borg scale the numbers run from 6 to 20. Check which scale a plan uses.

Sources 1, 9

Heart rate zones

Our zone 2 guide explains heart rate zones and the talk test, and our HIIT (high-intensity interval training) and VO2 max guides cover hard intervals. On a beta blocker, go by effort or the talk test rather than heart rate, as our zone 2 guide explains.

Check with your GP first if

For healthy adults, strength training is safe: in trials with more than 38,000 people, it didn't raise serious adverse events. Speak to your GP or cardiac team before hard sets if:

• You have a heart condition, or get chest discomfort, unusual breathlessness or dizziness when you're active.
• Your blood pressure is high and not yet controlled. Once it's controlled, low to moderate-intensity strength training with steady breathing is safe, the American Heart Association says.

Sources 16, 3

Call 999 now (911 in the US)

Stop and call 999 for:

• Chest pain that feels tight, heavy or like squeezing, or that spreads to your arms, neck, jaw, stomach or back.
• Chest pain with sweating, feeling sick, light-headedness or breathlessness, or sudden chest pain or discomfort that doesn't go away.
• Severe difficulty breathing: gasping, choking or not able to get words out.
• Someone who faints while exercising.
• A sudden, extremely painful headache, or a headache with weakness or numbness, or difficulty speaking.

Sources 35, 36, 37, 38

Call NHS 111 (in the US, your doctor or urgent care)

Get advice the same day for:

• A headache brought on or made worse by exercising, coughing, sneezing or bending down.
• In the days after a hard session, especially a new or much bigger one: muscle pain or weakness far worse than normal soreness, with dark (tea or cola-coloured) urine or passing less urine than usual. These can be signs of rhabdomyolysis, a rare but serious breakdown of muscle, so get medical help straight away.

Sources 38, 39, 40

Stop, and get checked before you train again

Dizziness, unusual breathlessness, chest pain or pressure, or palpitations (a racing, pounding or irregular heartbeat) during strength training.

Source 16

See a GP

• A faint at any time other than during exercise (fainting during exercise needs 999).
• A sprain or strain that's getting worse, or isn't getting better.
• Tiredness that rest and sleep don't relieve.

Sources 37, 41, 42

Checking sets, and effort with a heart condition

Take sets to failure only on machines, or with safety arms or a spotter, and stay 2 to 3 reps short if you're older. In cardiac rehab, follow your team's targets; our heart disease guide covers how rehab uses the Borg scale.

Source 3

"RPE 8 means 8 out of 10 effort"Strong evidence

On the lifting scale it means about 2 reps left. On the general 0 to 10 scale, 7 to 8 is vigorous.

Sources 1, 2, 9

"Beginners always stop too close to failure"Emerging evidence

On average the error runs the other way: people stop with about one more rep in them than they think.

Source 7

"You can't use reps in reserve until you're experienced"Emerging evidence

Training experience didn't change accuracy in the meta-analysis or in a study of trained and untrained men and women, and small studies suggest practice helps. Start with 3 or 4 in reserve while you learn.

Sources 7, 18, 8

"Half-points make your training more precise"Mixed evidence

Half-points such as 8.5 aren't in the published scale, and people are usually about a rep out.

Sources 1, 7

"Sets to failure are what build muscle"Strong evidence

Training to failure gave no clear extra muscle or strength in two meta-analyses, though growth may rise a little closer to failure. Failure sets also felt harder and less pleasant.

Sources 4, 5, 6, 43

"A bar-speed app knows your reps in reserve"Mixed evidence

Predictions from bar speed were often 2 or more reps out, and less accurate on some lifts.

Sources 31, 32