30, 90 or even 300 seconds. How to choose an optimal rest interval length between sets to maximize muscle growth? I’ve heard many conflicting approaches which made me a little confused. Starting from as little as 30 seconds and ending with several minutes. However, I’m sure that there should be some evidence-based guidance which allows us to more accurately select the best rest interval length. Thus, I’ve collected some credible studies and hope they’ll help you to quickly find out what works for you.
What is rest interval?
Rest interval is the time between consecutive sets. Sometimes, it is called interset rest interval or rest period as well.
For bodybuilding purposes, rest intervals are classified as:
- Short: less than 30 seconds
- Moderate: 60 to 90 seconds.
- Long: 3 minutes or more.
Overall, exercisers used to consider that shorter rest intervals were better for endurance, long for strength, and moderate for muscle building.
In addition, for other sports disciplines, we can find other rest interval classifications. It’s popular to express rest intervals as the work-to-rest ratios. For example, long is 1:12 – 1:20 whereas 1:3 – 1:5 (work/rest) is a short rest interval.
A Tricky Question
At first glance, the question about the best rest interval length could seem simple. You can use Google search and find a countless amount of articles, but prepare yourself. The opinions will differ.
Even nowadays there is no 100% certainty regarding muscle growth. As a result, researchers cannot provide us with clear answers about muscle building. Plus, rest interval lengths affect muscles in different ways.
Longer rest intervals allow us to lift heavier weights that are essential for many drug-free bodybuilders. In addition, if you work out really hard, your nervous system needs more time for recovery than usual. Otherwise, you move one step closer to overtraining.
However, taking extended rest intervals doesn’t allow you to perform many exercises within a workout session, so this reduces total workout volume. As you might know, workout volume is an important variable for gaining size as well. By the term workout volume we understand the amount of exercises, or total workload performed over a period of time.
On the other hand, some prefer and argue in favor of a short rest interval. This increases growth hormones and testosterone levels.
I even found one related large-scale analysis, which was carried out in 2009 and compiled information from 35 different studies. Guess what!? The researchers emphasized the hormonal spike importance in muscle building. And that followed an advice for exercising to use moderate intensity with in between-set rest intervals of 30 to 60 seconds while exercising.
However, this short hormone spike does not always result in an additional growth and what’s more, may significantly increase stress hormone cortisol levels as well.
Today, I simply can’t neglect to mention lactic acid. So many times these two words pop up in the discussions regarding interset rest period. Take a brief look at this in more detail.
Lactic acid builds up in the muscles during short bouts of relatively high intensity exercise. It occurs as a byproduct when our body utilizes glucose as a primary energy source. On the one hand, some amounts of lactic acid acts as a helper for muscle growth. On the other hand, too much lactic acid triggers muscular fatigue and consequently, you can’t continue to work out with such heavy weights. And that’s bad!
Our body systems need some time to reduce the level of lactic acid. Usually, it could take much more time than a couple of minutes to return lactic acid levels back to normal!!! For most people, enough rest could be between 5 – 20 minutes to significantly decrease lactic acid levels. It’s one of the reasons why those who are seeking strength improvement should consider a longer rest interval.
As I mentioned before, from bodybuilding perspectives, such a long rest interval isn’t always the best choice. It results in the reduction of total workout volume.
The latest studies and recommendations
I hope so far you get the point of the current evidence. In short, rest interval depends on many factors and, especially, two of them stand out: lactic acid and hormones. As a result, many current recommendations on how to choose rest interval lengths are based on them.
However, as I said before, the evidence that short hormonal spikes are enhancing muscle growth is lacking. For every individual exerciser it would be difficult to control the level of hormones and lactic acid as well. So, if you can’t control them by yourself, you should only rely on the general statistics and opinions.
In addition, very short rest periods could lead to incorrect exercise technique.
For these reasons, many fitness experts shift their focus. They advise monitoring how rest interval affects total workout volume. Your selected rest interval length should allow you to maintain a high training volume. As a consequence, it could let you pack on more muscle. I hope you agree that workout volume is easy to count and monitor.
There are some studies, which compared various rest time impact on muscle growth. I’ve compiled information about the studies and results in the table below.
As you can see, the results vary from one study to another. There is no one right rest interval length which suits every situation. As I mentioned previously, ‘your selected rest interval length should allow you to maintain high training volume.´ If it does, then you are on the right track. Usually, it’s between 1.5 to 4 minutes. I would like to add that the results of these studies support it as well.
How it looks in practice…
For example, you are doing bench press, hit 10 reps in the first set and then rest for 60 sec. Next you do the second set and hit only 5 reps. It’s a very significant decrease in the performance. In this case, you should extend rest time between sets. You rest for 2 min and perform the third set of 9 reps. Now, everything is ok without significant reduction in volume.
Be flexible! When you will work out using heavier weights and/or doing compound movements your rest interval should be longer than using lighter weight and/or isolation movements. If you need to, don’t be afraid to take a longer rest as many powerlifters do. Evidence reveals that powerlifting-type workout routines affect positively on muscle growth as well.
Keep in mind that rest interval in only one of many training variables. Don’t overestimate and, of course, similar to other training variables you should periodically change it.
How to maintain a short rest interval?
Maybe for some reasons you want to adhere only a short interval. What to do?
Over time, our body can adapt to a shorter rest interval. You can try to gradually cut down rest time. However, you can do it only to a certain extent (!?!?!).
In general, you’ll have difficulties to maintain resistance following strictly short rest interval protocol.
There was an investigation on how four different rest intervals: 30 s, 1 min, 2 min, 3 min, 5 min affected resistance and volume during 5 sets in the bench press. The 30 sec and 1 min rest interval groups experienced a reduction in resistance and volume over subsequent sets of 15 – 50 %. As a result, the total workout volume decreased. In contrast, 5-minute rest interval protocol reduction was observed only in the 5th set. If you want to maintain repetition range 8 – 12 using only a 60 sec rest interval, you should reduce the resistance of 5 % to 10 % load after each set. In this case, you can maintain a repetitions range of 8 -12.
An exception is young sportsmen (teenagers) who can maintain prescribed rep ranges even after short rest interval length.
How to control rest interval length?
From a time control perspective, there are two types of rest intervals: self-suggested (based on our feelings) and fixed (1 min, 3 min, and so on). I know many exercisers who don’t use any timers to control rest interval length. They rely on their intuition. There is a finding which reveals that self-suggested rest intervals tend to be shorter than fixed rest intervals. It allows for a shorter workout duration and it’s ideal when you have a busy schedule or are pushed for time.
Actually, I partly agree with this kind of approach. I observed that short rest interval followers tend to extend their rest. In contrast, when you choose longer rest intervals then self-suggested might be shorter. For newbies who want to be punctual and control rest interval length, I strongly suggest to use timers. Habitual exercisers can choose either approach.
What to do between sets?
Looking at your smartphone, chatting with your gym mates, or just sitting and dreaming big dreams… How to better spend time between sets?
Let’s dive into this question.
As long as your goal is to boost muscle growth, you should opt for proper inter-set activity which can maximize muscle building.
As suggested by some studies, a good bet is changing the activity to doing some light aerobic exercises between sets. We can describe it as an active inter-exercise recovery.
One study compared how three different 5 min inter-set activities (pedaling, stretching exercises, or lying supine) influenced high-intensity intermittent exercise results. After the comparison, performance was 3-4% higher for the pedaling group than the remaining two. However, we should keep in mind that this study wasn’t conducted for any specific bodybuilding workout. For this reason, we can’t be 100 % sure about its efficiency.
Next time when you go and hit the iron, instead of sitting, try to do some light exercises between sets. For example, between heavy sets of squats take some light upper body exercises. Let’s see if it does improve your results!
Another option is to focus mentally on your next set and, especially, if it is expected to be heavy. You should think and imagine that you can lift your target weight or even how your muscles are getting bigger and bigger. Nowadays, there are many various psychological techniques that can help to deal with that, e.g. emotional freedom technique. Even Arnold Schwarzenegger used his imagination to motivate himself to lift heavier and grow bigger.
Sometimes exercisers do some static stretches prior to a workout or between sets. I’ve heard two opposing arguments about this kind of approach: positive and negative. In order to satisfy my desire to find the truth, I compiled information from 6 related studies. And guess what? They revealed that static stretching isn’t a good activity prior to, or between sets. Almost all studies showed negative or mixed results about such routines.
For instance, one study analyzed how four different stretch protocols affected sprint performance. These four stretching protocols were: no-stretch of either leg, both legs stretch, forward leg and rear leg in the starting position stretch. Apart from non-stretch protocol, the remaining protocols increased sprinting time by about 0.04 sec in 20 meters distance.
Leave static stretching for cool-down as a good means for improving flexibility, mobility and enhancing recovery.
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- Weir, Joseph & L. Wagner, Loree & J. Housh, Terry. (1994). The Effect of Rest Interval Length on Repeated Maximal Bench Presses. The Journal of Strength & Conditioning Research. 8. 10.1519/1533-4287(1994)008<0058:TEORIL>2.3.CO;2.
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