Rest between sets

Geschatte leestijd: 6 minuten How long should you rest between sets for muscle growth? Recent research suggests that you should take 3 minutes of rest between sets for hypertrophy. However, it is questionable whether you should adjust your rest based on this research.

“Langere rust tussen sets voor hypertrofie”

The reason for this article is a study by Schoenfeld and colleagues that will soon be published in the Journal of Strength and Conditioning Research [1]. It shows that a rest period of 3 minutes between sets results in more muscle strength and more muscle mass than a 1-minute rest. 23 male students with at least six months of strength training experience were divided into two groups. Both groups did the same training. One group rested for 1 minute between sets, and the other group rested for 3 minutes. The training itself consisted of seven exercises per session:

• Barbell back squat
• Leg press
• Leg extension
• Flat barbell press
• Seated military press
• Lat pulldown
• Seated Cable row

So, well-known strength exercises to make it as relevant as possible for most people who train in the gym. The training was done three times a week, for 8 weeks. They did 8-12 repetitions per exercise with a weight that ensured this was also the maximum achievable (until muscle failure). So, especially focused on muscle mass in terms of the number of repetitions. Various results were then measured, such as:

• Muscle growth: The thickness of the trained muscles
• Muscle strength: 1RM test for the bench press and squat (with what weight can you do one good repetition)
• Muscle endurance: Maximum number of bench press repetitions with 50% 1RM (with half the weight with which you can do one repetition)

The three-minute rest period resulted in a significantly greater improvement in both muscle strength* and muscle mass (although the difference depends on which muscle and which part of it). Only in terms of muscle condition was there no (significant) difference between the two groups. *What I don’t understand is that the strength increase was tested with the bench press while this, or another specific chest exercise, was not included in the training program.

Remarkable outcome regarding the influence on

muscle growth The outcomes are surprising. Longer rest periods are often recommended for maximal strength development as in powerlifting and weightlifting. That is not a surprising outcome in this study. However, for hypertrophy, we normally recommend shorter breaks. The first reaction is therefore that this should be compared to other research. The researchers themselves also note this and they already refer to many of the comparable studies. There are, of course, many more possibilities than 1 or 3 minutes. They refer to a study in which 2 minutes and 5 minutes of rest were compared [2]. In that study, there was no difference in muscle growth. You could therefore think that 1 minute is too short for muscle growth and therefore 3 minutes of rest in this latest study yielded more. However, this is not in line with another study from the University of Southern California where 4 minutes of rest resulted in less muscle growth than 1 minute of rest between sets [3].

Rest between sets and its influence on training duration and volume

When reading the summary of Schoenfeld’s research, I wondered what this means in practice. After all, if you take longer breaks, your training will take longer, or you can do fewer exercises or sets in the same time. So, I wondered what this meant in the study. In the full text, you can read that they did the aforementioned seven exercises, both groups in the same order. There is mention of a full-body workout (or “total body” as the researchers call it) where all seven exercises are repeated three times a week. Here’s the important point: Both groups did 3 sets per exercise. So, a total of 21 sets and 20 times of rest in between. The group that took longer rest, therefore, needed a total of 20*2 minutes = 40 minutes more time for rest. In other words: The group that took shorter rest had 40 minutes more time. This is a huge difference. For some, the total training time is just over 40 minutes. So, the group that took shorter rest could stop training much earlier and start eating faster, for example, or more exercises or more sets could be done in the same time. Both groups received 24 grams of protein, which had to be ingested within an hour after training. However, it is not clear how the extra time was utilized by the group that took shorter rest. It is therefore also not clear whether this extra time was well utilized or whether they simply sat still during that time, did not stimulate their bodies anymore, and did not eat. In the study where 4 minutes of rest were compared to 1 minute of rest, the researchers did it differently. The training volume was made equal. What does that mean? In the group that takes longer rest periods, more weight can be moved or more repetitions can be done. If you multiply the number of repetitions by the weight being trained with, you will get a certain total training volume. To ensure that the group that takes shorter breaks still reached the same volume, this group did an extra set in the study from the University of Southern California. In that case, the shorter rest period of 1 minute resulted in more muscle growth than 4 minutes of rest. So, it is possible that when the training volume is equalized (and the extra time is well utilized), the shorter break still leads to more muscle mass. Another difference, by the way, was that the University of Southern California had older men as the test group (average age 68) instead of trained young men.

Too many variables for a hard conclusion

What I really appreciate in Schoenfeld’s recent research and colleagues is that the researchers themselves place all relevant annotations with the research. Such as the noted difference in training volume, the way muscle growth was measured at one location of the muscle (while muscle growth can occur locally at specific points of the muscle), the large differences in results within a group and even per muscle group in one person, and finally the relatively short duration of the research. This does not make the outcome black or white and does not offer the clear outcome that many would like to have. However, that is the reality, complex and dependent on a large number of variables of which we can hardly ever investigate the interaction in all possible situations. Let alone in an environment where all other variables are controlled. For example, they could not rule out differences in daily nutrition. The researchers have referred to and discussed more studies than I have here. I have omitted them because they do not change the practical recommendations that follow from the research. The researchers acknowledge that the fact that 1 minute of rest is optimal for muscle growth is not in line with current recommendations and based on what they know from other studies, they also recommend taking 2 minutes of rest between sets for muscle growth (although they did not investigate that rest time themselves). As a practical point, they finally indicate that the training in the long rest group did indeed take almost twice as long. Apart from the impact on energy and nutritional needs, a training session that lasts twice as long may simply not be practical or feasible for many. It is also not known whether the “optimal rest” depends on the exercise being performed. For example, with an exercise like the squat, you activate more muscle mass and use more energy. In theory, it is possible that a longer rest period is needed than when training, for example, your forearms (just to mention a contrast).

Rest between sets: the practice

So, it seems a bit like an article in the newspaper. The title is a catchy, sensational headline: “longer rest periods between sets promote strength and hypertrophy in trained men.” If you read the article yourself, it is immediately toned down to the point where little remains of that catchy headline. It may be useful to have some kind of bandwidth in mind, for example, not to rest for less than 2 minutes and not more than 4 minutes. However, it is not possible to name an exact “optimal rest time” between sets. In practice, I will mainly leave this to what my body indicates. I try to feel when I have rested enough by checking if my breathing has normalized and my heart rate has dropped again. In the back of my mind, I am always counting up to 90 to have an indication of the elapsed time, but the next set is only started when I am physically and mentally ready for it. References

1. Schoenfeld, Brad J. et al. Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men.Journal of Strength & Conditioning Research:Post Acceptance: November 20, 2015 doi: 10.1519/JSC.0000000000001272
2. Ahtiainen, JP, Pakarinen, A, Alen, M, Kraemer, WJ, and Hakkinen, K. Short vs. long rest period between the sets in hypertrophic resistance training: influence on muscle strength, size, and hormonal adaptations in trained men. J Strength Cond Res 19: 572-582, 2005
3. Villanueva, MG, Lane, CJ, and Schroeder, ET. Short rest interval lengths between sets optimally enhance body composition and performance with 8 weeks of strength resistance training in older men. Eur. J. Appl. Physiol. 115: 295-308, 2015.