The most heated debates in the gym, in addition to the correct execution of exercises, revolve around the optimal rest time between sets. How long should you actually pause between two sets?

Key points:

1. If you’re training for muscle growth, getting enough rest between sets is essential for the quality of those sets. That quality is determined by the amount of mechanical tension you create through especially the stimulating repetitions just before muscle failure.

2. Aim to do about five stimulating reps in each set. If you do too few – because you only get a few reps, or because you stay too far away from muscle failure – you have to do more sets to compensate.

3. Very short rest is therefore no use: it comes at the expense of the amount of stimulating repetitions you can do in the next set. Several studies show that you build more or faster muscle mass when you use longer rest periods between sets.

4. Only start your next set when you feel completely ready physically and mentally: you must be able to use all your available strength and achieve a good mind-muscle connection. To this end, all fatigue from the previous set must be sufficiently resolved: the local fatigue (in both the target and auxiliary muscles), the central fatigue and the cardiovascular fatigue.

5. If you find it difficult to feel when you are completely ready for your next set, use as a guideline 1-2 minutes for isolating exercises, 2-3 for most compound exercises and 3-5 for squats and deadlifts. If necessary, use a stopwatch.

6. Shorter rest periods may not be optimal for muscle growth, but they can provide other benefits, such as improving fitness and burning more fat. The choice for more metabolic strength training, with short or even no rest breaks, therefore depends on the training goal(s).

7. If you train purely for strength gain instead of muscle growth, rest for 3 to 5 minutes, depending on the intensity of the set. Beginners are likely to arrive with shorter breaks.

WHAT IS THE FUNCTION OF RESTING BETWEEN SETS?

In short, the function of rest times between sets is that you can do sets that are effective enough for your training goal. If you’re training for muscle growth, each set should give you about five reps that are stimulative. That is, you do five reps that are close to muscle failure, also known as the effective reps. After all, with those repetitions most motor units in the muscle are addressed, which creates the most mechanical tension. Mechanical tension is the main training stimulus for muscle growth.

The total number of reps of the set, in theory, doesn’t matter. If you’re using a light weight, you may need fifteen reps to get to the five stimulative ones. Use a very heavy weight and you will almost immediately reach those five stimulating repetitions. Which is not to say that the repetitions before those five aren’t stimulating at all, but that aside.

So let’s say you do a set of ten reps to near muscle failure (ie with 1 Rep In Reserve). Reps 6-10 are about those five stimulating reps. Then if you hardly rest, say only ten seconds, you may only be able to do two repetitions to near-muscle failure in your next set. That is too little to count as a full set.

Mind you, muscle failure means that the muscle gives up: there is local fatigue (see next paragraph). If you have to stop a set due to some other type of fatigue, such as cardiovascular, you may still be a long way from muscle failure. Even then you ‘miss’ some or all of the stimulating repetitions.

In summary:
If you’re training for muscle growth, getting enough rest between sets is essential for the quality of those sets. That quality is determined by the amount of mechanical tension you create through the stimulating repetitions just before muscle failure.

TYPES OF FATIGUE

After completing the last rep, just before or even all the way to muscle failure, you experience an overall fatigue. You don’t have to think about picking up that dumbbell and barbell again and doing so many repetitions again. It is not only the trained muscle that is fatigued.

Neuromuscular fatigue, as this general fatigue is officially called, is a complex process about which not everything is known yet. We can more or less distinguish the following types of fatigue, which, however, are also intertwined.

LOCAL FATIGUE

After you have trained a muscle to (near) failure, you have used up energy that is stored in the muscle cell. This is done according to the energy system ATP-CP ^[ i ] . The muscle is therefore tired and needs time to recover. We call this local (also called peripheral) fatigue.

How exactly does that ATP-CP system work? ATP (adenonsine tri-phosphate) enables the muscle cell to convert chemical energy into movement. ATP is available for a few seconds and then needs to be topped up. This is done by splitting creatine phosphate (creatine phosphate, or CP).

It is generally assumed that the stocks of ATP and CP are fully replenished after three minutes of rest ^[ ii ] . Which does not automatically mean that you should only then start your next set. After all, 85 to 90 percent of ATP and CP stocks are already restored within one minute. And in bodybuilding or hypertrophy training, in addition to the ATP-CP system, the glycolytic system also supplies energy (ie energy from glucose), so that the body needs less rest between sets than with pure strength training (see also below).

Looking purely at local fatigue, you could often retrain a muscle within a minute with at least five stimulating repetitions. However, there are also other types of fatigue that play tricks on you.

CENTRAL FATIGUE

Central fatigue is the fatigue in the central nervous system, ie the brain and spinal cord. When this nervous system is fatigued, it has trouble activating your muscles. So even though the muscle itself is no longer fatigued, it no longer receives the correct instructions from the brain to use its full strength potential.

Long sets with light weights cause more central fatigue than short, intense sets ^[ iii ] . A set of 20 barbell squats to near muscle failure is much more tiring than a set of six to near muscle failure.

Central fatigue is somewhat more abstract than local fatigue. For example, it is reasonably easy to feel whether a muscle is fresh enough to train again, based on, among other things, the concentration of lactic acid in the muscle. If you still don’t feel ready for the next set – that is, you can’t deliver optimal power and achieve a good mind-muscle connection – you still have central fatigue.

It may take a few minutes for the central fatigue to resolve and so you can start your next set, while the local fatigue will likely resolve much sooner.

CARDIOVASCULAR FATIGUE

Cardiovascular fatigue is the fatigue related to the heart and blood vessels. This fatigue manifests itself very clearly in your breathing, just as it can during or after cardio exercises. In strength training, it is greatest after longer sets of compound exercises, in which several muscle groups are working simultaneously. If you start your next set too soon, you won’t be able to breathe enough for optimal strength performance. Your lungs ‘fail’, as it were, before your muscles do.

Cardiovascular (or metabolic) oriented strength training is not wrong in itself, if fat burning and fitness improvement are your main goals – see also below. But if muscle growth is your (main) goal, you have to make sure that you can fill your lungs with each set.

In summary:
Doing a set creates several types of fatigue, which are closely related: local fatigue, central fatigue and cardiovascular fatigue. Some fatigue resolves faster than others.

CHECKLIST

How long you need to rest before all types of fatigue are sufficiently resolved depends on several factors:

the type of exercise (isolating versus composite);
the absolute intensity (short versus long sets);
the relative intensity (~1-3 RIR versus complete muscle failure);
the moment in the workout (central fatigue increases the longer the workout lasts).

To determine the appropriate minimum rest time after a set, bodybuilding coach Mike Israetel recommends the following checklist ^[ iv ] :

Has the muscle locally recovered enough to be able to do another five stimulating repetitions?
Is central fatigue no longer a limiting factor?
Is cardiovascular fatigue no longer a limiting factor?
Are the synergistic muscles no longer a limiting factor?

An example at point 4 is your forearms on bent-over rows. If your back muscles have recovered sufficiently, but your forearm muscles have not yet, you won’t be able to produce optimal grip strength. As a result, your set can still fail prematurely, so before the target muscles have passed five repetitions for muscle failure.

In summary:
Only start your next set when you feel completely ready physically and mentally: you must be able to give all your available power and achieve a good mind-muscle connection. To this end, all types of fatigue must be resolved, including local fatigue in auxiliary muscles.

RESEARCH BASED GUIDELINES

Nice, such a checklist, but in practice it is not that easy, to feel good when you are completely ready for your next set. But perhaps we can also learn something from scientific research.

It has long been believed that one minute of rest between sets is optimal for muscle growth. That dogma still prevails. A dive into the literature, however, shows that this is hardly substantiated by scientific research.
A 2009 study favored longer rest periods (2.5 minutes versus 1 minute), at least in twelve untrained subjects ^[ vi ] .
According to a 2014 meta-study by Brad Schoenfeld and Menno Henselmans, you cannot simply state that rest times in hypertrophy training can or should be shorter than in pure strength training ^[ vii ] .
Research by Schoenfeld and Henselmans themselves, conducted on 21 trained young men, showed that it is better to take a break for 3 minutes between sets than 1 (see infographic) ^[ viii ] . The strength athletes studied all followed the same training program, in which sets of 8 to 12 repetitions were done, each time until muscle failure.
Update 03/07/2020: a new study by Schoenfeld shows that there is hardly any difference in the number of repetitions you can do with 2 minutes versus 3 minutes of rest between sets of a compound exercise (the leg press)^[ xiii ] . The muscle growth was not measured, however, only the acute training performance was looked at.
If you train with very light weights (40%1RM), ie in high rep ranges, it makes little difference to muscle growth whether you rest for 30 seconds or 2.5 minutes, according to another study by Schoenfeld ^[ ix ] .
From several studies we know you have to do less sets if you rest longer. Short rest periods therefore undermine the effectiveness of sets, probably because you can do fewer (stimulating) repetitions than if you wait a little longer.

Three minutes of rest is better than one, according to hypertrophy expert Brad Schoenfeld. (source: TEC Fitness, Facebook link expired, 3/19/2018)

CONCLUSIONS

Based on the available published research, we can conclude that you generally benefit from longer rest periods for muscle growth. If you start your next set too soon, the remaining fatigue will be at the expense of the quality of that set. And therefore also at the expense of muscle growth.

Only if you train with very light weights (≤ 40%1RM) you may be able to suffice with relatively short rest times. That may be because you have to do a lot of light reps before you get to the heavy ones. Although with extremely long sets, cardiovascular fatigue will start to play tricks on you, we think.

Most reputable coaches therefore recommend rest times of 1-2 minutes for isolation exercises and 2-5 minutes for compound exercises. The latter margin is quite wide, but that is because the fatigue with barbell squats and deadlifts in particular is much greater than with the overhead press, for example. After a set of heavy squats, you may need 4 to 5 minutes to fully recover, while after a set of shoulder presses you may need a 2 to 3 minute break.

If necessary, use a stopwatch to keep track of your rest times.

In summary:
Very short rests are not optimal: it comes at the expense of the amount of stimulating reps you can do in the next set. Studies also show that you build more or faster muscle mass when you use longer rest periods between sets. Guideline: 1-2 minutes for isolation exercises, 2-5 minutes for compound.

WHAT IF YOU’RE SHORT ON TIME?

If you have little time to train, there is a great temptation to use short rest periods. We have now seen that this is probably at the expense of muscle growth. To achieve optimal muscle growth, you should do more sets, so you probably lose at least as much time as if you rested longer (and therefore have to do fewer sets). If you have little time to train, you will simply have to accept that you will build muscle mass a little less quickly. Because that’s not a disaster, because gains don’t run away.

It is also true that with short rest periods you create more metabolic stress. Although this comes at the expense of the mechanical tension that is important for muscle growth, according to some studies, metabolic stress in itself can also be a ‘path’ to muscle growth. Short rest periods also make your training more cardiovascular, which usually has a beneficial effect on fat burning and fitness. That is why some people consciously opt for metabolic strength training, with short rest periods, supersets and so on. Keep in mind, however, that this is not a pure bodybuilding workout and so it will not give you maximum muscle growth.

In summary:
Short rest periods are not optimal for muscle growth. If you can do too few stimulating repetitions in a set by resting briefly, you will have to do more sets to compensate. Short rest periods can offer other benefits, such as improving fitness and burning more fat. The choice for more metabolic strength training, with short or even no rest breaks, therefore depends on your training goal(s).

CAN YOU REST TOO LONG?

Resting unnecessarily long between sets, for example because you are chatting with fellow athletes or are diligently editing your Instagram selfie, can in principle not hurt muscle growth. Resting too short is much more harmful than resting too long.

However, don’t make a habit of lengthy rest periods, as they can negatively impact your training performance: you’ll cool down too much causing you to do extra warm-up sets, you’ll lose focus, and/or you may not benefit from the momentum of multiple sets within a single set. Apart from that, you spend unnecessarily long in the gym.

If you consciously do metabolic strength training, use short rest periods (see previous section). Resting for too long then detracts from the accumulation of metabolites that you are deliberately trying to achieve.

In summary:
Do not rest longer than necessary.

REST TIMES FOR STRENGTH

If muscle size isn’t that important to you and you simply want to be the strongest in your gym, different rules apply. Clearer rules than in hypertrophy training.

For optimal results in this area, rest for 3 to 5 minutes between sets ^[ xi ] . Shorter rest periods come at the expense of exercise intensity, as the body needs a minimum of three minutes to fully replenish its phosphate energy supply (ATP-CP). In our opinion, 5 minutes is not a hard upper limit, although you have to make sure that your body does not cool down too much between sets.

BEGINNERS VS ADVANCED

With beginners, however, it doesn’t matter to your strength whether you rest 2, 3 or 5 minutes between sets. Brazilian researchers came to this discovery ^[ xii ] . They wanted to know what the influence of the rest interval between sets is on your muscle strength. They divided 34 untrained men in their twenties into two groups. They had both groups follow a 12-week training program, in which only the rest intervals differed between sets. One group rested twice as long between sets as the other group. Furthermore, the two groups trained identically.

The participants trained all major muscle groups twice a week with two sets of 8-12 repetitions until momentary muscle failure (read: until they could no longer perform a (complete) repetition without assistance).

Before and after the training program, participants’ one-rep max (1RM) on the bench press and leg press was tested. The 1RM increased almost equally in both groups. In other words, there was no statistically significant difference in strength gain between the group that rested briefly and the group that rested longer between sets. Conclusion: rest intervals between sets do not influence strength gains for novice strength athletes if the other training parameters (training frequency, volume and intensity) are equal. The influence on hypertrophy and endurance has not been studied.

Practical conclusion: beginners should therefore limit their breaks between sets to save time and train more efficiently.

Finally, we should note that although the 1RM, or pure strength, of the subjects was tested, they did not follow a strength training program; After all, 2 sets of 8-12 reps are typical ‘bodybuilding’ parameters, ie variables that focus on muscle growth rather than strength gain.

We estimate that if the subjects had followed a more intensive training program, ie a program with heavier weights and fewer repetitions, the group with the longer rest intervals would have trained more effectively and showed more strength gains.

CONCLUSION

For pure strength training, the following guidelines apply:

Rest, depending on the severity of the set, from 3 to 5 minutes. Not any longer, because then you cool down too much and increase the chance of injuries;
Beginners are likely to arrive with shorter breaks.

The rules for resting between sets are not set in stone, but it is evident that there is a difference between training for muscle growth and training for strength.

In summary:
If you train purely for strength gain instead of muscle growth, rest for 3 to 5 minutes, depending on the intensity of the set. Beginners are likely to arrive with shorter breaks.

IN SUMMARY

1. If you’re training for muscle growth, getting enough rest between sets is essential for the quality of those sets. That quality is determined by the amount of mechanical tension you create through the stimulating repetitions just before muscle failure.

3. Very short rests therefore do not make sense: it comes at the expense of the amount of stimulating repetitions you can do in the next set. Studies also show that you build more or faster muscle mass when you use longer rest periods between sets.

4. Only start your next set when you feel completely ready physically and mentally: you must be able to give all your available power and achieve a good mind-muscle connection. To this end, all fatigue from the previous set must be sufficiently resolved: the local fatigue (in both the target and auxiliary muscles), the central fatigue and the cardiovascular fatigue.

5. If you find it difficult to feel when you are completely ready for your next set, use as a guideline: 1-2 minutes for isolation exercises, 2-5 minutes for compound exercises. If necessary, use a stopwatch.