Repetitions in reserve: how to dose your effort – Knowledge

1. What this article is about

In strength training, every set raises the same question: how heavy should the weight be, and when do you stop? In our practice we answer that question with a single number. It is called "repetitions in reserve". It means how many repetitions you could still have done at the end of a set.

This article explains the number from the ground up. It shows what research says about its effect. It shows how accurately people can estimate their reserve, and where the estimate goes wrong. It gives the critics of the method their say. And it describes step by step how to calibrate your own sense of the reserve.

The article is written for patients. In our practice we treat you like athletes in one respect: we dose your training. Someone building strength after an operation, with osteoarthritis or at the age of 75 needs the same number as an athlete. The target values differ. The method is the same.

One thing belongs at the start. Almost all studies of this method were done in young, healthy and mostly male people. On older adults there is a single study of accuracy, and it came out differently from the studies in younger people. On people in rehabilitation there is one small study in cardiac patients. What this article says for you is therefore partly transfer and experience. The text says at each point what is proven.

2. What "repetitions in reserve" means

You do twelve repetitions on the leg press and put the weight down. Now you ask yourself: how many more could I have done? Your sense says: a thirteenth and a fourteenth, the fifteenth would have been the end. Then you had two repetitions in reserve. Specialists abbreviate this as RIR [1].

The number describes your effort. Two in reserve means: hard, but with distance to the end. Zero in reserve means: nothing more was possible. Five in reserve means: noticeable, but far from the end. The number is independent of the weight and of the exercise. Two in reserve on the leg press with 80 kilograms and two in reserve standing up from a chair without using your hands describe the same effort.

2.1 What "muscular failure" means exactly

Zero repetitions in reserve presupposes that "the end" is clearly defined. Researchers have proposed a definition [3]. Muscular failure is present when you attempt another repetition and the movement stops despite full effort. The bar no longer goes up. The leg no longer straightens.

To be distinguished from that is stopping by your own decision. You stop because it burns, because you are out of breath or because you are afraid of the next repetition. At that moment further repetitions would still have been possible. This distinction is the core of the whole article. The reserve counts repetitions the muscle could still perform. Discomfort, breathlessness and fear belong to other numbers. Section 6.3 comes back to this.

Execution is part of the definition too. If you manage the last repetition only with momentum, with a rounded back or with half the range of motion, it counts as failed [3]. In our practice the rule is: the end of a set is reached when the next clean repetition does not come.

2.2 The scale from 10 to 5

In sport the reserve is often expressed as an effort scale. A research group from the USA proposed a scale from 1 to 10 in 2016 whose upper steps correspond directly to the reserve [2]. In practice you only need the upper half:

• 10 = 0 in reserve. Nothing more was possible.
• 9 = 1 in reserve. One more would have worked.
• 8 = 2 in reserve.
• 7 = 3 in reserve.
• 5 to 6 = 4 to 6 in reserve. It was work, but without strain.
• Below 5 = light. This set counts as a warm-up.

We talk with you in repetitions, not in scale points. "Two in reserve" is understood by everyone at once. "An 8" has to be translated first. Studies use both forms, and they mean the same thing [1].

3. Why we work with this number

Classically, strength training is planned in percentages of the maximum weight. For that you need a test in which you lift the heaviest weight you can manage once. For many patients that test is out of the question. It loads a freshly operated knee, a painful joint or a sensitive cardiovascular system all at once. The reserve bypasses the test. It describes your effort directly.

Three further reasons speak for the number.

Percentages fit the person poorly. How many repetitions someone manages with 70 per cent of their maximum weight differs from person to person and from exercise to exercise [30]. A study in 15 young beginners shows the reverse: the same effort corresponded to quite different percentages in the deadlift [4]. One repetition in reserve lay at 88 per cent of the maximum weight in a set of three repetitions, at 84 per cent in a set of five and at 79 per cent in a set of eight. The same reserve, three different numbers on the weight plate. Repeated on two days, almost the same weight came out in the same people. The deviation lay between 3 and 6 per cent [4].

The number adapts to your day. After poor sleep, after a cold or at the end of a demanding week you manage less. A percentage from a test six weeks ago knows nothing of that. The reserve knows, because you feel it today [1]. Conversely, the weight rises by itself as you get stronger.

Without a target, most people choose too light. In a study of 30 people without training experience, participants were allowed to choose their own weight. All of them chose below 60 per cent of their maximum weight. The range lay between 42 and 57 per cent [5]. Such weights are insufficient for strength and muscle growth. The reserve gives you an anchor: if eight more repetitions would have been possible at the end of the set, the weight was too light.

4. How close to the end? What the studies say about the effect

The reserve is a dial. You can train with five in reserve, with two or with zero. What comes out depends on the goal.

4.1 For strength you do not need the end of the set

A research group from the USA, Australia, New Zealand and England pooled in 2024 all studies in which the reserve at the end of the set was known. Instead of comparing two groups, they calculated a curve across the whole range from zero to well over five in reserve [6]. For maximal strength no relationship was found across the whole range. Someone who trained with four in reserve became about as strong as someone who went to zero.

For practice this means: if you want to build strength, you may stop two to four repetitions before the end. On current knowledge you lose nothing by it.

4.2 For muscle growth, closeness to the end matters, with diminishing returns

For muscle growth the curve looked different. The closer sets were taken to the end, the greater the gain in muscle thickness [6]. The relationship was continuous. A set with one repetition in reserve brought more than one with four. The authors themselves call their calculation exploratory rather than conclusive. One reason is concrete: in most studies the reserve was estimated, not measured. How large that error is, section 5 shows.

Two further pieces of work put the curve in context. A summary of 15 studies found a very small advantage in muscle growth for sets taken to the end compared with sets with reserve [7]. When "the end" was strictly defined as muscular failure, the advantage disappeared. And in a study of 18 trained people each leg trained differently for eight weeks [8]. One leg went to muscular failure on the leg press and leg extension, the other stopped at two and one repetition in reserve respectively. Muscle thickness in the thigh increased equally on both sides: by 0.18 centimetres.

For practice this means: if muscle growth is the goal, closeness to the end pays off. The last repetition to a standstill adds, on current knowledge, nothing measurable over one to two in reserve.

4.3 What muscular failure costs

Sets to the end have a price, and it can be measured.

Fatigue. In one study, 24 trained women and men did six sets of bench press with the same weight on three days [9]. Once to muscular failure, once to one repetition in reserve, once to three in reserve. Four minutes afterwards, movement speed with a test weight had fallen by 25 per cent after failure, by 13 per cent after one in reserve and by 8 per cent after three in reserve. After 24 hours the first two conditions were still 3 per cent below baseline, the third was 2 per cent above. After 48 hours all had recovered. Discomfort, muscle soreness and general well-being worsened the closer the sets went to the end.

An older study in ten trained men confirms the direction [10]. Three sets of ten repetitions to failure needed 24 to 48 hours longer for recovery than six sets of five repetitions. The total number of repetitions was the same in both cases.

Blood pressure. At maximal effort with held breath, blood pressure rises sharply. A study in five bodybuilders with a measuring catheter in the arm artery found a mean of 320 over 250 millimetres of mercury during the two-legged leg press [11]. In one person the value exceeded 480 over 350. Even the one-arm biceps curl to failure raised it to 255 over 190. These values come from five young, highly trained men with weights near their maximum. They show the direction, and they are the reason we practise breathing with you and avoid the end of the set.

Execution. Someone at the end moves differently. The back rounds, the knee drifts inwards, the shoulder hitches up. For a joint in rehabilitation, precisely this last repetition is the riskiest. Two in reserve keep the movement clean.

4.4 Does the reserve beat a fixed plan?

Five studies have compared this directly.

• 31 trained men, 12 weeks of squats. One group followed a fixed plan with percentages from a test at the start. The other chose the weight set by set according to their reserve. Both got stronger, the second more so: by 11.7 and 10.8 per cent in the front and back squat compared with 8.3 and 7.1 per cent [12].
• 21 trained men, 8 weeks of squats and bench press. Both groups gained similarly. A small advantage for the reserve group was possible but not certain [13].
• Summary of 15 studies. Whether the weight was chosen by reserve or by percentage made no difference to strength gain [14].
• 82 older adults, average age 72, 11 weeks. Four ways of increasing the weight were compared: by percentage, by effort scale, by reaching a repetition target, and by reserve with always at least one repetition short of the end. Strength, walking speed, standing up from a chair and the other everyday tests improved equally in all four groups. The effort-scale group found the training more pleasant and easier to keep up than the other three [15].
• 16 men with coronary artery disease, average age 60, 9 weeks of cardiac rehabilitation. One half trained by percentage, the other by reserve. Both gained equal strength, on the leg press for example 24 kilograms in the reserve group [16]. This study is small and a first attempt.

The picture is consistent. The reserve works at least as well as a fixed plan. In one study it worked better. Its advantage lies less in the result than in the way there: no maximal test, no outdated percentages, and for older adults a training they find more pleasant.

5. How accurately do people estimate their reserve?

The whole method stands or falls with one question: is the number you name correct? Researchers test this with a simple experiment. They have a person call out their reserve in the middle of a set. Then the person carries on until nothing more is possible. The difference between the call and reality is the error.

A summary of 12 such studies with 414 participants gives the answer [17]. On average, participants underestimated their reserve by 0.95 repetitions. The confidence interval ranged from 0.17 to 1.73. So they could almost always have done a little more than they thought. The error went in one direction: too cautious. Practically never in the other.

This one repetition is an average across all conditions. Behind it are situations in which the estimate is very good, and others in which it is off by three to five repetitions. Those differences matter more for your training than the average.

5.1 When the estimate is good

Close to the end. In an Australian study of 81 people, the error was about one repetition as long as five or fewer repetitions remained [18]. With seven to ten remaining it grew to over two. The summary of 12 studies found the same: the closer to the end the call came, the more accurate it was [17].

With heavy weight. Heavy weights allow only a few repetitions. With few repetitions the estimate is more accurate than with many [17], [18]. A set of six to ten repetitions is easier to judge than one of twenty.

In later sets. The first set of an exercise is almost always judged too cautiously. In a study of 20 trained men, participants consistently named a smaller reserve in the first set than they actually had [22]. From the second set on, the number fitted better. The body needs one set to know how the weight feels today.

In single-joint exercises. The estimate on the chest press was more accurate than on the leg press [18]. On the leg press many large muscles work at the same time, and breathing becomes an issue. Both make it harder to sense the individual muscle.

5.2 When it is off

Far from the end. In a study of 25 men, participants called out their reserve three times during a set of squats: at five, at three and at one repetition in reserve [21]. Then they continued to failure. At "one in reserve" the error was 2.05 repetitions. At "three in reserve" it was 3.65. At "five in reserve" it was 5.15. Someone estimating far from the end is guessing.

Before the set. In a study of 141 people, participants were asked before each set to predict how many repetitions they would manage [19]. The measurement error lay between 2.6 and 3.4 repetitions. A prediction before the set is clearly worse than a call in the middle of it.

When you believe you are at the end. In two experiments with 14 and 24 trained people, participants stopped the leg extension when they believed they could not manage another repetition [20]. In a second round they were instructed to continue until the movement really stopped. On average they managed two more repetitions. So even the feeling "nothing more is possible" is two repetitions too early. For you as a patient that is good news: your own end has a built-in safety margin.

With many repetitions. The more repetitions a set has, the larger the error becomes [21], [24]. In sets of 15, 20 or 30 repetitions the reserve is therefore only a rough figure.

Whether you know the weight makes no difference. In the study of 20 men, one half knew how much weight was loaded, the other did not [22]. Accuracy was the same. Your sense follows the effort, and the number on the plate changes nothing about it.

5.3 Experience helps less than you would think

An obvious thought is: someone who has trained for a long time estimates better. The studies barely support it.

• In the summary of 12 studies, training status made no difference to accuracy [17].
• Nor in the Australian study of 81 people [18].
• In a study of 27 men and 31 women with biceps curl, triceps pushdown and rowing, neither sex nor training years nor experience with the scale played a role [23].
• In a study of 16 people, eight experienced and eight beginners estimated equally accurately in the squat [25]. The authors suspect that training years matter less than whether someone has ever experienced the end of a set.
• In the study of 141 people there was a slight hint that experienced people predict better [19].

Even more revealing is a study that followed the question over time. Nine trained men did bench press three times a week for six weeks [24]. In each session they called out their reserve in the last set and then took the set to failure. Over the six weeks the estimate did not become more accurate. They received the feedback indirectly each time by finishing the set. Even so, they barely learned.

The same shows in professionals. 259 certified strength coaches watched videos of people doing squats and biceps curls to failure [26]. They were to estimate the reserve. After one third of the set they were off by 4.8 repetitions on average, after two thirds by 2.0, shortly before the end by 1.2. The coaches' years on the job played no role in this. What helped was something else: whoever had already seen the same person in another exercise estimated markedly better the second time.

From these findings we draw a conclusion for section 7. Experience alone helps little here. What calibrates is the comparison between call and reality, made consciously and written down.

5.4 What we know about older adults

Of the 31 studies that a 2024 review found on the use of the reserve, participants were almost everywhere young, healthy and mostly male adults [28]. 855 people in total. On older adults we found a single accuracy study, and it is recent.

25 people with an average age of 68 did the chest press with 65 per cent of their maximum weight [27]. They were to stop at a reserve of six, of four and of two repetitions. At six in reserve the number was right: the error was 0.1 repetitions. At four in reserve they stopped on average 1.6 repetitions too early. At two in reserve they stopped 2.1 repetitions too early. So they had about four in reserve when they called two. They rated their effort on a scale from 1 to 10 almost the same for all three targets: 7.3, 7.6 and 8.0.

The result runs contrary to the findings in younger people. There the estimate becomes more accurate close to the end. In these older adults it became less accurate close to the end. The authors conclude that in older adults the reserve may be too imprecise as a prescription for the weight. As a count of how much someone has trained, they consider it usable together with the effort scale.

Three things help to put this in context. First, it is one study with 25 people and a single exercise. Second, participants had been familiarised with the method only briefly before the measurement. Third, the 11-week study of 82 older adults shows that training with the reserve works nonetheless and brought as much strength as the three other methods [15]. For us it follows: with older patients we estimate the reserve together, we watch the movement, and we rely less on the bare number. Section 7.9 describes how.

A Spanish research group shows another route for older adults. In training with elastic bands they had participants rate the effort after the very first repetition [29]. That number predicted well how many repetitions were possible in total. The advantage: the weight can be corrected before the set is over. We use this question with bands and light weights.

6. What the critics say

The method has critics, and they have good arguments. Some come from the same researchers who developed the method.

6.1 The number is estimated, and the error is larger than the target

The target is often "two in reserve". The error at two in reserve is one to two repetitions [17], [21]. Someone who says "two" therefore actually has between two and four. Someone who says "zero" still has two [20]. The target and the error are the same size. The researchers who studied 141 people therefore write that the reserve should be prescribed with caution [19]. For muscle growth the error could reduce the result, because people stop too early.

Our reply: the error almost always goes in the same direction, namely too cautious. For patients that is the right direction. And the error can be reduced. Section 7 shows how.

6.2 The same number describes different stimuli

Two in reserve after five heavy repetitions and two in reserve after 25 light repetitions carry the same number. The stimulus to the muscle and the fatigue behind it are different. A research group from Florida compared in 2022 the different ways of specifying closeness to the end [30]. It notes that to this day there is no uniform way of measuring it. Even the term "failure" is used differently across studies: sometimes as the movement stopping, sometimes as stopping by one's own decision, often without any definition.

For you this means: the reserve alone does not describe your training. The repetition count belongs with it. "Two in reserve at eight repetitions" is a complete statement. "Two in reserve" alone leaves half of it open.

6.3 Effort, discomfort and pain are three things

The reserve asks what your muscle could still do. People often answer a different question: how unpleasant it is right now. Two Israeli researchers showed in 2020 that effort scales in sports science are used with different meanings and that effort, discomfort and fatigue get mixed up in the process [31]. They propose asking separate questions for discomfort and fatigue.

How strongly the answer depends on the reference point is shown by a further study from the same group. 25 trained people rated the same effort twice [32]. Once the reference was the hardest execution of that one exercise, once the hardest effort they could imagine at all. For the squat the rating was 9.4 one time and 5.5 the other, on a scale to 10. For a hand-grip device 9.4 and 3.9. The same work, almost double the number. The reserve is somewhat better protected against this error because it counts in repetitions. It is not entirely free of it: someone who confuses "the end" with "unpleasant" calls a reserve that is too small. A study of 38 people found something reassuring here: how accurately someone estimated the reserve depended strongly on how close the end was, and hardly at all on how exhausted the person felt [35].

For patients a third point comes in: pain. A set that ends because of pain in the knee has not reached muscular failure. The reserve does not describe it. What to note in that case is in section 7.6.

6.4 Speed as a measurable alternative

The closer you get to the end, the slower each repetition becomes, even when you push as fast as you can. The research group that proposed the scale in 2016 found in 29 people a close relationship between the measured speed of the bar and the effort called out [2]. From this a separate approach has developed: a sensor measures the speed, and the set ends when it has dropped by a set proportion. Critics of the reserve see this as the better method because it measures instead of estimating [30].

Two limitations come with it. First, the method needs a device on every bar and machine. Second, the relationship between speed and reserve differs from person to person. In a Norwegian study with 19 trained people and 2'972 measurements, speed explained on average only 30 per cent of the reserve called out [33]. In some people the two fitted well together, in others hardly at all. The authors conclude that speed and reserve complement rather than replace each other. In the summary of 15 studies, control by speed brought similar strength gains to a fixed plan [14].

What you can take from this needs no sensor: watch your speed. Section 7.4 describes it.

6.5 Is the question even the right one?

Three English researchers objected in 2022 that research asks a yes-or-no question where a continuous quantity exists [34]. "To failure or not" is the yes-or-no question. The effort behind it is a continuum from zero to maximal. The calculation across the whole curve in section 4 is the answer to that objection [6]. And that calculation rests on estimated reserves with the error from section 5. The curve is therefore an approximation.

We stand by this uncertainty. The reserve is a practical quantity with a known error. It is the quantity you can apply without a test, without a device and anywhere. Its value arises with calibration.

7. How to calibrate your estimate

A scale is calibrated by placing a known weight on it and comparing the reading. You calibrate your sense of the reserve the same way: you name a number, check reality and remember the deviation. The following nine steps summarise what the studies from section 5 suggest and what has proven itself in our practice.

7.1 The calibration set: once to the end, under supervision

The core of calibration is a single set that you take to the real end. Only then do you learn how far your call is off.

1. Choose an exercise on a machine where a standstill is harmless. Leg press, leg extension, chest press or rowing are suitable. Squats and bench press with a free bar are suitable only with a spotter.
2. Do two warm-up sets with a light weight.
3. Load a weight with which you manage about eight to twelve repetitions.
4. Start the set. Say "three" out loud when you believe you have three repetitions left. Say "one" when you believe you have one left. Your physiotherapist notes both.
5. Carry on until the movement stops despite full effort or until execution becomes untidy. The professional stops you at that point.
6. Compare. Did you manage three more after "one"? Then your call was two too low. That is your personal calibration value.

Repeat the calibration set every three to four weeks with the same exercise. A single set to the end in four weeks costs little recovery [9]. It also shows you whether you have got stronger. For people with heart disease, with a freshly operated joint or with uncontrolled high blood pressure, the calibration set is dropped. There we calibrate through the observation described in section 7.9.

7.2 Estimate close to the end, and estimate twice

The call at five in reserve is uncertain by five repetitions [21]. The call at one in reserve is uncertain by two repetitions. So never estimate at the start of a set. Wait until it gets noticeably hard. Then name a first number, for example "three". Carry on and name a second, for example "one". The second number is more accurate, and the gap between the two shows you whether your sense is consistent. If only one repetition lay between "three" and "one", you know your first number was too high.

7.3 The first set is for feeling

The first set of an exercise is judged too cautiously [22], [23]. So treat it as a feeler set. Choose the weight from last time and observe how it feels today. Correct from the second set on. If you say "four" at the end of the first set, add a little in the second. If you say "zero" and execution suffered, take some off. The reserve is a number for the second and third set.

7.4 Watch the speed of the last repetitions

If you push as hard as you can and the movement still slows down, you are approaching the end [2]. That is your measurable sign without a device. Three observations help:

• The repetition takes noticeably longer than the first ones although you are pushing equally hard. That corresponds to about three to four in reserve.
• You get briefly stuck in the middle of the movement and then get through after all. That corresponds to about one to two in reserve.
• You have to help with momentum, twisting or holding your breath. That is the end. The set is over.

These three stages are experience values from practice. The relationship between speed and reserve differs from person to person [33]. Check in the calibration set at which speed your last three repetitions lie.

7.5 Stay at six to twelve repetitions

The reserve is more accurate with few repetitions than with many [17], [21]. Sets of six to twelve repetitions are the best range for calibration. They are heavy enough for a clear sense and light enough for clean execution. Sets of 20 or more repetitions have their place, for instance with bands or directly after an operation. There the reserve is a rough figure, and we rely more on the first-repetition question from section 5.4 [29].

7.6 Separate muscle, breath and pain

The reserve counts only what the muscle could still do. If you stop for another reason, write that reason down. Three reasons are common.

Breath. You stop because you run out of air, but the legs could have continued. Note "breath" and the reserve you had in the legs. The breathing technique in section 8 helps against the breathlessness.

Discomfort. It burns in the muscle and you do not want to go on. The muscle could have continued. The burning is normal in sets with many repetitions. Someone used to it underestimates their reserve less often [25]. A calibration set shows you how much still comes after the burning.

Pain. A joint or a tendon hurts and you stop because of it. In that case write down the pain on a scale from 0 to 10, and the reserve stays blank. With tendon complaints and with long-standing pain, exercises may hurt to a certain degree. Pain up to 5 out of 10 during the exercise was considered acceptable in a study of 38 people with Achilles tendon complaints, provided it had settled again by the next morning [36]. A summary of seven studies with 385 participants found a small short-term advantage for painful exercises over pain-free exercises, and no difference after months [37]. Which pain limit applies to you, we set together. It is recorded separately from the reserve.

7.7 Define what "the end" means for you

The study on reference points shows that the same effort can be called 5.5 or 9.4 depending on what you compare it with [32]. So define the reference point before you estimate. For the reserve it is: "The end is when the next clean repetition in this exercise with this weight does not come." Compare with this exercise, with this weight, today. Do not compare with a mountain run, with childbirth or with the hardest training of your life.

The calibration set from section 7.1 gives you this reference point as a memory. Someone who has once felt what the last repetition on the leg press is like has an anchor that no description can replace [25].

7.8 Keep a log

Six weeks of training without a conscious comparison did not improve the estimate in one study [24]. Coaches estimated better as soon as they had seen the same person once before [26]. Both speak for writing the numbers down. Note for each set the weight, the repetitions and your reserve. For the calibration set, note the deviation as well. After four calibration sets you see a pattern: perhaps you are always two too low on the leg press and almost right on the chest press. Then you know how to read your own call.

For writing things down you can use our strength diary (in German and French). It has a field for the reserve in every set and runs without an internet connection. A sheet of paper does the job too.

7.9 What we do about it in the practice

Your physiotherapist calibrates with you. Four things are part of it.

• We watch speed and execution. Professionals are off by 1.2 repetitions on average shortly before the end of a set [26]. Together with your call that makes two estimates which check each other.
• We ask about the first repetition. With bands and light weights we ask after the very first repetition how heavy it felt [29]. If the answer is "light", we change the weight before the set is over.
• We do the calibration sets with you. We stop you when execution breaks down, and we decide for which exercises a calibration set is an option for you.
• We keep the numbers apart. Reserve, breath, discomfort and pain stand side by side in your programme. What is slowing you down decides what we change next.

8. Which reserve suits you

From sections 4 and 5, three target ranges follow. They apply to the working sets after the warm-up.

• Strength as the goal: 2 to 4 repetitions in reserve. Going closer to the end adds nothing for strength on current knowledge [6] and costs recovery [9].
• Muscle growth as the goal, with no reasons against: 0 to 2 repetitions in reserve. The gain rises with closeness to the end [6]. The last repetition to a standstill adds nothing measurable over one to two in reserve [8].
• Older adults and rehabilitation: 2 to 3 repetitions in reserve. That is a deliberate distance from the calculated optimum for muscle growth. The reasons are blood pressure at maximal effort [11], clean execution and recovery [9]. In the study of 82 older adults, a reserve of at least one repetition brought the same strength as the methods without that margin [15].

Because you underestimate your reserve by about one repetition [17], your call of "two" is in reality often a "three". For the target range in rehabilitation that is fine. Someone aiming for muscle growth who calls "two" should know that they are more likely at three, and add a repetition depending on their calibration value.

On breathing. Breathe out while lifting and in while lowering. Do not hold your breath. If the last repetition only works with held breath, the set is over. That is the simplest measure against the blood pressure peaks from section 4.3.

On the last set. On the last set of an exercise you may go closer to the end than on the first. After it nothing follows that could suffer from the fatigue. On the first set two in reserve is the target, on the last it may be one.

9. When to get in touch

Stop training and call the emergency number 144 if any of these occurs during or after a set:

• Pressure or pain in the chest, arm, jaw or between the shoulder blades.
• Sudden breathlessness that does not improve at rest.
• Dizziness with visual disturbance, weakness on one side of the body or difficulty speaking.
• A sudden, very severe headache.

Get in touch with the physiotherapy practice if any of these applies:

• You regularly end sets because of pain and never because of the muscle.
• A joint is swollen or warmer than the other one on the morning after training.
• Your pain after training lasts beyond the next morning.
• Your calibration sets are off by four or more repetitions, and that does not change after three attempts.
• You have been at the same weight and the same reserve for four weeks without the repetitions rising.
• You are unsure whether a calibration set is an option for you.

10. What you should know

• Repetitions in reserve count what your muscle could still do at the end of the set [1]. Zero means: the next clean repetition does not come [3].
• The number replaces the maximal test and adapts to your day. The same reserve corresponds to 79 to 88 per cent of the maximum weight depending on set length [4].
• For strength you do not need the end of the set [6]. For muscle growth, closeness to the end matters, with no measurable addition from the last repetition [6], [8].
• Sets to the end cost recovery and drive blood pressure up [9], [11].
• The reserve works at least as well as a fixed plan, also in 82 older adults and in 16 men in cardiac rehabilitation [12], [15], [16].
• People underestimate their reserve by about one repetition [17]. Close to the end and with heavy weights the estimate is good, far from the end it is off by three to five [21].
• The feeling "nothing more is possible" comes two repetitions too early [20].
• Experience alone hardly improves the estimate [17], [24], [26]. What helps is the comparison between call and reality.
• In 25 older adults the estimate was less accurate close to the end than far from it [27]. We estimate together with you and watch the movement.
• Criticism: the number is estimated, the error is as large as the target, and the same number describes different stimuli [19], [30]. Effort, discomfort and pain get mixed up [31].
• Calibrating means: every three to four weeks one set to the end on a safe machine, a call at three and at one, deviation written down.
• Target ranges: strength 2 to 4, muscle growth 0 to 2, rehabilitation and older age 2 to 3 repetitions in reserve.

References

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[1] 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. https://doi.org/10.1519/SSC.0000000000000218

[2] Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, Helms E, Esgro B, Duncan S, Garcia Merino S, Blanco R. Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve. Journal of Strength and Conditioning Research. 2016;30(1):267–275. https://doi.org/10.1519/JSC.0000000000001049

[3] Steele J, Fisher J, Giessing J, Gentil P. Clarity in reporting terminology and definitions of set endpoints in resistance training. Muscle & Nerve. 2017;56(3):368–374. https://doi.org/10.1002/mus.25557

[4] Lovegrove S, Hughes LJ, Mansfield SK, Read PJ, Price P, Patterson SD. Repetitions in Reserve Is a Reliable Tool for Prescribing Resistance Training Load. Journal of Strength and Conditioning Research. 2022;36(10):2696–2700. https://doi.org/10.1519/JSC.0000000000003952

[5] Glass SC, Stanton DR. Self-selected resistance training intensity in novice weightlifters. Journal of Strength and Conditioning Research. 2004;18(2):324–327. https://doi.org/10.1519/R-12482.1

[6] Robinson ZP, Pelland JC, Remmert JF, Refalo MC, Jukic I, Steele J, Zourdos MC. 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;54(9):2209–2231. https://doi.org/10.1007/s40279-024-02069-2

[7] 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. https://doi.org/10.1007/s40279-022-01784-y

[8] Refalo MC, Helms ER, Robinson ZP, Hamilton DL, Fyfe JJ. Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. Journal of Sports Sciences. 2024;42(1):85–101. https://doi.org/10.1080/02640414.2024.2321021

[9] Refalo MC, Helms ER, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure, Determined by Repetitions-in-Reserve, on Neuromuscular Fatigue in Resistance-Trained Males and Females. Sports Medicine – Open. 2023;9(1):10. https://doi.org/10.1186/s40798-023-00554-y

[10] Morán-Navarro R, Pérez CE, Mora-Rodríguez R, de la Cruz-Sánchez E, González-Badillo JJ, Sánchez-Medina L, Pallarés JG. Time course of recovery following resistance training leading or not to failure. European Journal of Applied Physiology. 2017;117(12):2387–2399. https://doi.org/10.1007/s00421-017-3725-7

[11] MacDougall JD, Tuxen D, Sale DG, Moroz JR, Sutton JR. Arterial blood pressure response to heavy resistance exercise. Journal of Applied Physiology. 1985;58(3):785–790. https://doi.org/10.1152/jappl.1985.58.3.785

[12] Graham T, Cleather DJ. Autoregulation by "Repetitions in Reserve" Leads to Greater Improvements in Strength Over a 12-Week Training Program Than Fixed Loading. Journal of Strength and Conditioning Research. 2021;35(9):2451–2456. https://doi.org/10.1519/JSC.0000000000003164

[13] Helms ER, Byrnes RK, Cooke DM, Haischer MH, Carzoli JP, Johnson TK, Cross MR, Cronin JB, Storey AG, Zourdos MC. RPE vs. Percentage 1RM Loading in Periodized Programs Matched for Sets and Repetitions. Frontiers in Physiology. 2018;9:247. https://doi.org/10.3389/fphys.2018.00247

[14] Hickmott LM, Chilibeck PD, Shaw KA, Butcher SJ. The Effect of Load and Volume Autoregulation on Muscular Strength and Hypertrophy: A Systematic Review and Meta-Analysis. Sports Medicine – Open. 2022;8(1):9. https://doi.org/10.1186/s40798-021-00404-9

[15] Buskard ANL, Jacobs KA, Eltoukhy MM, Strand KL, Villanueva L, Desai PP, Signorile JF. Optimal Approach to Load Progressions during Strength Training in Older Adults. Medicine and Science in Sports and Exercise. 2019;51(11):2224–2233. https://doi.org/10.1249/MSS.0000000000002038

[16] Gismondi A, Iellamo F, Caminiti G, Sposato B, Gregorace E, D'Antoni V, Di Biasio D, Vadalà S, Franchini A, Mancuso A, Morsella V, Volterrani M. Rate of Perceived Exertion Based on Repetitions in Reserve Versus Percentage of One-Repetition Maximum for Resistance Training Prescription in Cardiac Rehabilitation: A Pilot Study. Journal of Cardiovascular Development and Disease. 2024;12(1):8. https://doi.org/10.3390/jcdd12010008

[17] Halperin I, Malleron T, Har-Nir I, Androulakis-Korakakis P, Wolf M, Fisher J, Steele J. Accuracy in Predicting Repetitions to Task Failure in Resistance Exercise: A Scoping Review and Exploratory Meta-analysis. Sports Medicine. 2022;52(2):377–390. https://doi.org/10.1007/s40279-021-01559-x

[18] Hackett DA, Cobley SP, Davies TB, Michael SW, Halaki M. Accuracy in Estimating Repetitions to Failure During Resistance Exercise. Journal of Strength and Conditioning Research. 2017;31(8):2162–2168. https://doi.org/10.1519/JSC.0000000000001683

[19] Steele J, Endres A, Fisher J, Gentil P, Giessing J. Ability to predict repetitions to momentary failure is not perfectly accurate, though improves with resistance training experience. PeerJ. 2017;5:e4105. https://doi.org/10.7717/peerj.4105

[20] Armes C, Standish-Hunt H, Androulakis-Korakakis P, Michalopoulos N, Georgieva T, Hammond A, Fisher JP, Gentil P, Giessing J, Steele J. "Just One More Rep!" – Ability to Predict Proximity to Task Failure in Resistance Trained Persons. Frontiers in Psychology. 2020;11:565416. https://doi.org/10.3389/fpsyg.2020.565416

[21] Zourdos MC, Goldsmith JA, Helms ER, Trepeck C, Halle JL, Mendez KM, Cooke DM, Haischer MH, Sousa CA, Klemp A, Byrnes RK. Proximity to Failure and Total Repetitions Performed in a Set Influences Accuracy of Intraset Repetitions in Reserve-Based Rating of Perceived Exertion. Journal of Strength and Conditioning Research. 2021;35(Suppl 1):S158–S165. https://doi.org/10.1519/JSC.0000000000002995

[22] Mansfield SK, Peiffer JJ, Hughes LJ, Scott BR. Estimating Repetitions in Reserve for Resistance Exercise: An Analysis of Factors Which Impact on Prediction Accuracy. Journal of Strength and Conditioning Research. Online vorab veröffentlicht am 31. August 2020. https://doi.org/10.1519/JSC.0000000000003779

[23] Remmert JF, Laurson KR, Zourdos MC. Accuracy of Predicted Intraset Repetitions in Reserve (RIR) in Single- and Multi-Joint Resistance Exercises Among Trained and Untrained Men and Women. Perceptual and Motor Skills. 2023;130(3):1239–1254. https://doi.org/10.1177/00315125231169868

[24] Remmert JF, Robinson ZP, Pelland JC, John TA, Dinh S, Hinson SR, Elkins E, Canteri LC, Meehan CM, Helms ER, Hall ME, Laurson KR, Zourdos MC. Changes in Intraset Repetitions in Reserve Prediction Accuracy During Six Weeks of Bench Press Training in Trained Men. Perceptual and Motor Skills. 2023;130(5):2139–2160. https://doi.org/10.1177/00315125231189098

[25] Droguett FAB, Festa RR, Quintana NAT, Gomez-Lopez J, Ojeda ÁH, Farias-Valenzuela C, Giakoni-Ramírez F, Jofré-Saldía E. Objective Accuracy in Estimating Repetitions in Reserve in the Back Squat: An Analysis between Experienced vs. Novice Subjects. Journal of Human Kinetics. 2026;102:145–158. https://doi.org/10.5114/jhk/205218

[26] Emanuel A, Har-Nir I, Obolski U, Halperin I. Seeing Effort: Assessing Coaches' Prediction of the Number of Repetitions in Reserve Before Task-Failure. Sports Medicine – Open. 2022;8(1):132. https://doi.org/10.1186/s40798-022-00526-8

[27] Gómez-Redondo P, Alcazar J, Valenzuela PL, Ara I, Alegre LM, Mañas A. Validity of repetitions in reserve for prescribing resistance exercise in older adults. Experimental Gerontology. 2025;210:112884. https://doi.org/10.1016/j.exger.2025.112884

[28] Bastos V, Machado S, Teixeira DS. Feasibility and Usefulness of Repetitions-In-Reserve Scales for Selecting Exercise Intensity: A Scoping Review. Perceptual and Motor Skills. 2024;131(3):940–970. https://doi.org/10.1177/00315125241241785

[29] Colado JC, Gene-Morales J, Chulvi-Medrano I, Babiloni-Lopez C, Moreno-Murcia JA, Saez-Berlanga Á. Perceived Exertion, Neuromuscular Activation, and Training Volume in Older Adults: Validating RPE-1 in Moderate-Velocity Elastic Band Resistance Training. International Journal of Sports Physical Therapy. 2026;21(1):13–25. https://doi.org/10.26603/001c.147897

[30] Pelland JC, Robinson ZP, Remmert JF, Cerminaro RM, Benitez B, John TA, Helms ER, Zourdos MC. Methods for Controlling and Reporting Resistance Training Proximity to Failure: Current Issues and Future Directions. Sports Medicine. 2022;52(7):1461–1472. https://doi.org/10.1007/s40279-022-01667-2

[31] Halperin I, Emanuel A. Rating of Perceived Effort: Methodological Concerns and Future Directions. Sports Medicine. 2020;50(4):679–687. https://doi.org/10.1007/s40279-019-01229-z

[32] Malleron T, Har-Nir I, Vigotsky AD, Halperin I. Rating of perceived effort but relative to what? A comparison between imposed and self-selected anchors. Psychology of Sport and Exercise. 2023;66:102396. https://doi.org/10.1016/j.psychsport.2023.102396

[33] Paulsen G, Myrholt R, Mentzoni F, Solberg PA. Exercise type, training load, velocity loss threshold, and sets affect the relationship between lifting velocity and perceived repetitions in reserve in strength-trained individuals. PeerJ. 2025;13:e19797. https://doi.org/10.7717/peerj.19797

[34] Fisher JP, Steele J, Smith D. Intensity of effort and momentary failure in resistance training: Are we asking a binary question for a continuous variable? Journal of Sport and Health Science. 2022;11(6):644–647. https://doi.org/10.1016/j.jshs.2022.03.002

[35] Hackett DA, Selvanayagam VS, Halaki M, Cobley SP. Associations between Perceptual Fatigue and Accuracy of Estimated Repetitions to Failure during Resistance Exercises. Journal of Functional Morphology and Kinesiology. 2019;4(3):56. https://doi.org/10.3390/jfmk4030056

[36] Silbernagel KG, Thomeé R, Eriksson BI, Karlsson J. Continued sports activity, using a pain-monitoring model, during rehabilitation in patients with Achilles tendinopathy: a randomized controlled study. American Journal of Sports Medicine. 2007;35(6):897–906. https://doi.org/10.1177/0363546506298279

[37] Smith BE, Hendrick P, Smith TO, Bateman M, Moffatt F, Rathleff MS, Selfe J, Logan P. Should exercises be painful in the management of chronic musculoskeletal pain? A systematic review and meta-analysis. British Journal of Sports Medicine. 2017;51(23):1679–1687. https://doi.org/10.1136/bjsports-2016-097383

Transparency

• Authorship: Roger Hilfiker
• AI assistance: Literature search and text draft were produced with Claude (Anthropic). Roger Hilfiker checked all statements, figures and sources and revised the text.
• Created: 5 September 2026
• Last updated: 5 September 2026
• Sources: the 37 papers in the reference list. All DOIs were checked against the Crossref registry.
• How the sources were searched: queries of the Europe PMC and Crossref databases in September 2026 on "repetitions in reserve", proximity to muscular failure, accuracy of the estimate, self-regulation of the load, effort scales and applications in older adults and in rehabilitation. Where this text says that no study or only one study exists on a question, that refers to this search.
• Conflict of interest: Our practice doses strength training by this method and earns from the treatment. This text names the counter-arguments in a section of its own and says that the accuracy studies were done almost exclusively in young, healthy people.
• Funding: Physiotherapie Tschopp & Hilfiker, 3902 Glis. The article was produced from the practice's own funds.
• Next review: 5 September 2028. We also revise this article continuously as soon as new studies on accuracy in older adults or in rehabilitation appear.