We received a great question recently: “How do we reconcile studies where rest-pause and drop sets produce similar hypertrophy as straight sets, and data showing short rest periods produce less hypertrophy than longer?”
I’ve discussed this with other researchers (shout out to James Krieger; much of this is based on our discussion in Norway a few years back and his writings) without coming to a definitive answer. That’s exciting, as it means there’s more to learn about the nature of fatigue and hypertrophy. That said, just because this isn’t fully understood, doesn’t mean there isn’t a hypothesis consistent with the data. We’ll dive into this, and you’ll finish this blog with a nuanced understanding of rest periods, fatigue, their impact on hypertrophy, and ultimately, understand more than “short rest periods are bad”.
To do this, we’ll need to understand how we got to the modern concept of resting longer being superior for hypertrophy, from where exercise science used to be – believe it or not old recommendations were to rest for shorter periods for hypertrophy – and also discuss the nature of fatigue. So, strap in as we go through it all.
Originally, short rest periods were promoted as superior by the scientific community for hypertrophy based on data showing high volume training paired with restricted rest (the highest work:rest ratio) produced the largest acute growth hormone (GH) response. However, despite its name, “growth hormone” does not just impact growth. GH also regulates energy metabolism. Training with a high work:rest ratio creates a large, immediate demand for energy and increases lactate. Higher blood lactate levels create more acidic conditions. Given the metabolic role of GH, it’s unsurprising that GH release is enhanced under acidic conditions and that lactate and GH responses to exercise are significantly correlated. High work:rest ratio resistance training that increases GH (and lactate) can produce hypertrophy, but is the GH response necessarily the primary causative factor? Runners performing 30s sprints experience robust increases in GH (and lactate; which are strongly correlated); but, would you expect an entire 5x5RM full body training session with 3 minute rest intervals to produce less hypertrophy than a single 30s sprint, just because it resulted in a fraction of the GH response (1-5 vs 8-24 µg/L)? Obviously not! Indeed, a recent review examining this relationship concluded acute hormonal responses to exercise are not directly correlated with muscle growth per se.
With the background understood, let’s discuss the direct data on longer and shorter rest periods and hypertrophy. As the question indicates, most studies show that when matched for volume and effort, training protocols with longer rest periods produce similar or sometimes greater hypertrophy than those with shorter rest periods. However, “matched for volume and effort” is an important caveat. Most studies have participants train to failure. When you rest for a short period between sets, and get incomplete recovery, you’ll hit failure with fewer reps or have to reduce the load to perform the same number of reps. This is the principal hypothesis why shorter rest periods are thought to be worse for hypertrophy: less total mechanical stimulus (tension/load and volume of tension).
For example, Schoenfeld and colleagues compared two 3 day/wk full body protocols using either 1 min or 3 min rest periods with both groups doing 3 sets to failure on 7 exercises: squat, leg press, leg extension, bench, OHP, lat pulldown and cable row. In this case, load was adjusted each set to ensure failure occurred in the 8-12 rep range each set. Thus, number of sets were matched, effort per set was matched, but volume load (total tonnage lifted) was lower in the short rest group. Reason being, the short rest group had to decrease the weight more than the longer rest group to fail in the target rep range due to more cumulative fatigue set-to-set. However, if you were to rest a shorter period, but do additional sets to “make up” for lost volume due to incomplete rest, you can get on equal footing with a longer rest protocol as shown in a study by Ahtiainen and colleagues. In this way, you could argue that matching for effort and volume “biases” long rest periods to be better; because in reality, a group resting for a much shorter period between sets could accomplish more total sets in the real world, and perhaps end up doing more volume in the same time period.
But there are other ways researchers can match groups. If you match load instead of effort, you can actually bias a study the opposite way. Specifically, if you match % 1RM, you have to “hold back” the longer rest group. For example, specific to the “Good Question”, in a study on rest pause sets, the traditional group performed 3x6x80% 1RM, resting 3 minutes between sets. However, the rest-pause group performed their first set to failure at 80%, and then took a 20s mini-rest period, then did reps to failure with 80% 1RM, and repeated this rest-pause approach until they reached 18 reps. Thus, both groups performed 18 reps in total with 80% 1RM. However, in this case, the rest-pause group had a higher effort per set. Depending on the exercise, on average, you might be able to get 8-12 reps per set with 80% 1RM. Meaning, the traditional group on average was 2-6 reps short of failure for the whole study, while the rest-pause group was training to failure. Perhaps unsurprisingly, the rest-pause group outperformed the traditional training group in terms of performance and hypertrophy overall. With a study designed in this way, you could argue that matching for load and volume “biases” short rest periods to be better; because in reality a group resting for a longer period between sets could do more reps per set or lift a heavier load, and perhaps end up with a greater stimulus in the same time period.
So as you can see, depending on how you set up a study, a shorter or longer rest period could be seen to be better, as rest periods aren’t inherently bad or good; rather, we care about their impact on the stimulus you can impose when training. The logical conclusion, therefore, is whatever rest period allows for the theoretical “optimal” combination of load, volume, and proximity to failure, in an isolated training session, is ideal for hypertrophy. Rest too little, load and reps drop off too much per set, rest too much, you’ll only get a rep or two or 5kg more per set, when you would have been better off resting a minute less and doing an additional set per exercise.
But, it’s actually more complicated than that. Sets to failure with loads as low as ~30-40% 1RM are just as effective for hypertrophy as sets to failure with heavier loads so long as the set is sufficiently long, say at least ~5-6 reps. This observation has led to the hypothesis – that I agree with – that hypertrophy should be similar if effort is matched when the number of sets are also similar. You may be thinking…if that’s true, then it shouldn’t matter how long you rest! Incomplete rest makes fatigue accumulate faster, but so long as you don’t drop load below ~30-40% of 1RM or perform less than ~5-6 reps per set, it shouldn’t hinder hypertrophy. In fact, as the “Good question” hinted at, this notion is supported by the data on drop sets. In a study on drop sets, despite a reduction in load, similar hypertrophy was observed in a traditional group performing 3 sets to failure at 80% 1RM with 3 minute rest periods, compared to a group that did 80% to failure, followed immediately by dropping to 65, 50, 40, and 30% 1RM, going to failure on each drop, but ultimately performing a similar volume load to the traditional group.
With this understood, now we can revise our understanding to a new, more specific logical conclusion: whatever rest period allows for the theoretical “optimal” number of sets of at least ~5-6 reps, above ~30-40% of 1RM, at a sufficient proximity to muscle failure, should be ideal for hypertrophy. In actuality, this is only true in a vacuum, as obviously there is a limit to how much stimulus you can provide and recover from in a single session, but just for arguments sake let’s pretend that’s not the case.
So, are we there yet with this revised logical conclusion? We’re close, but unfortunately, there is still another wrinkle.
In a study where the anabolic response to training was measured, two groups performed four sets of leg press and leg extensions to failure with 75% 1RM, resting either 1 or 5 minutes between sets. Load was adjusted up or down by 5kg in cases where less than 8 or more than 14 reps were completed, which was rare. According to our revised conclusion, since load didn’t drop below 30-40%, reps didn’t drop below ~5-6, and sets and effort were equated, the anabolic responses should have been similar between groups. However, that’s not what happened; rather, the 1-minute rest period group had 50% of the initial muscle protein synthesis response that the 5-minute group had, and anabolic signalling was lower in the 1-minute rest group as well. Thus, it seems like there is something inherently inferior with short rest intervals. If we go back to the study I cited above by Schoenfeld and colleagues, this seems to be the case, as the 1 minute rest group did the same number of total sets, same reps per set (8-12), both groups trained to failure, and loads didn’t drop below ~30-40% 1RM; yet, the 1 minute rest group experienced far less hypertrophy. This also conflicts with our revised logical conclusion. Further, in the study I cited above by Ahtiainen and colleagues, if our revised conclusion was true, the short rest interval group should have grown more than the long rest interval group as they did additional sets to match volume load, instead of just getting back on equal footing with the longer rest group.
Now we’re at an impasse: both our original and revised conclusions are mutually exclusive, and the data appear in conflict. There could be an explanation though, and it may come down to the nature of fatigue.
Local muscular fatigue is helpful for the goal of hypertrophy. It’s the reason why a set of 20-35 reps can be as effective as a set of 8-12 reps for inducing muscle growth. Theoretically, a higher load set with fewer reps results in immediate recruitment of most muscle fibres, while a low-load set with many reps eventually recruits most fibres as local fatigue forces more and more fibres to “pick up the slack” as the set continues, ultimately getting you to the same stimulus. When local fatigue occurs, your nervous system is sending the signal to your muscles to contract and to keep performing reps, despite local fatigue preventing it from occurring. Locally, your muscles have given all they’ve got (Nice job muscles!).
However, not all fatigue is local. Central fatigue is characterised by a reduction in the actual neuromuscular signal to contract, which is inherently counterproductive for hypertrophy. So, what causes central fatigue? Ironically, very large amounts of local fatigue create a feedback loop that results in central fatigue. Specifically, a large, immediate cardiometabolic demand that drives up lactate can result in central fatigue. You heard that right, the exact type of training that was originally recommended to increase the GH (and lactate) response to training (high volume, short rest), can actually result in central fatigue inhibiting the signals for muscle contraction. Importantly, it’s not just your rest period that impacts cardiometabolic fatigue, another component is the amount of muscle mass that is trained. No one ever puked doing short rest periods between sets of curls, calf raises, or lateral raises to failure, but try doing that on squats and you better bring a bucket.
Specifically, in a study where single leg and bilateral leg extensions were compared, single leg extensions produced more local fatigue than extensions with both legs, presumably because when both quadriceps were trained, more cardiometabolic fatigue was generated and central fatigue kicked in, holding the participants back from generating the same amount of work, and subsequently, local fatigue. In fact, most of the training studies showing superior hypertrophy with longer rest intervals use a lot of compound movements (like the study by Schoenfeld I mentioned earlier). This also fits nicely with the drop set study I mentioned above, which was a study on dumbbell curls. Also, it explains some of the head scratching data where shorter rest periods trended towards outperforming longer rest periods. For example, in a study by Fink and colleagues, outcomes tended to favour short rest periods with 20RM sets compared to longer rest periods with 8RM sets; however, the training was only for the arms using isolation exercises.
This leads us to our final revision of our logical conclusion: whatever rest period allows for the theoretical “optimal” number of sets of at least ~5-6 reps, above ~30-40% of 1RM, at a sufficient proximity to muscle failure, so long as reductions in reps and load are primarily due to local rather than central fatigue, should be ideal for hypertrophy.
Is this the definitive answer to the question? Probably, but it’s possible something else might be going on. But as a hypothesis, it’s a pretty solid one that fits the data, is logical, and squares with anecdotal observations and experience.
The practical take homes are as follows:
- For compounds that train a lot of muscle mass, rest sufficiently so that you don’t generate a ton of cardiometabolic fatigue.
- Only use short rest, rest-pause, high-rep, drop, and failure sets on non-tiring isolation exercises.
- If you’re in great shape, you may get away with shorter rest periods but:
- To save time without hurting your gains, gradually acclimate to shorter rest periods over multiple sessions/weeks. Indeed, in two studies, a group resting 2 minutes grew similarly to a group gradually decreasing rest from 2 minutes by 15s per week, to eventually resting 30s between sets.
- You can also save time with antagonist paired sets. These are performed with short rest intervals after each exercise as one muscle group rests while you train the other (alternate an upper body push set with a pull, leg extensions followed by curls, etc.). This can be done with 30s to 1 min between sets. But, for compound push/pulls (vs bis/tris, or leg extension/curls), you need to be in good cardiovascular shape. Data shows this approach won’t compromise performance (if anything it might aid it).
Awesome read. I admire the way you present information; academic but digestible.
Disturbing fact: after watching every video you put out there, I can literally hear You reading the text in my head in that usual calm and collected manner, feels like listening to an episode from AO series.
Love your work.
Eric Helms says
Thank you! And apologies for my voice being in your head lol
Ahmad Abu Raddad says
Wow that was long and thorough and needed a lot of focus.
I like how you eased gradually into the final recommendation.
Another great article, thank you.
Eric Helms says
You’re very welcome!
Great article! I´m always learning something new from Eric. Interesting to see that lactate can result in central fatigue, i´ve heard many people in the fitness industry saying that was a mith.
Thanks, really aprecciate the content
Eric Helms says
Caio, thank you! And make sure you’re not learning something I’m not teaching haha. I didn’t say lactate results in central fatigue, I said “very large amounts of local fatigue create a feedback loop that results in central fatigue. Specifically, a large, immediate cardiometabolic demand that drives up lactate can result in central fatigue”. I didn’t say lactate is the causative factor
Sorry, i missunderstood. Thanks for clarifying!
Outstanding read indeed! The presentation and deep level of understanding combined with a know how to present this to the masses is phenomenal! Long live the TEAM!
I would be curious to see if there are any studies that correlate the ability to recover from this lactate threshold to aerobic training. It is commonly percieved that athletes with cardio vascular “training” recover from these affects quicker. Perhaps leading to a hybrid athlete that can lift more frequently because of their aerobic training.
Eric Helms says
check out the two studies at the end I cite on the groups resting 2 minutes vs decreasing by 15s every week down to 30s. At the very least this implies adapting to shorter rest intervals allows you to be more time efficient with the same program without sacrificing gains.
Damn. Your content just keeps getting better and better. Keep it up! You guys have been such an inspiration to me!
Tim K says
Great article and very helpful. There’s one thing I would like to get clarity on: would you say that there’s any downside to resting “too long” between sets (aside from the increase in overall length of the workout)?
Related to that, I both work from home and train at home, and in the past I’ve thought about stuff like doing sets of curls or lateral raises spread throughout the day instead of adding them on to my already-to-long powerlifting workouts. Tacking them on to a workout might add an extra 10-15 minutes even if I do antagonist paired sets, whereas dispersing them through the day (with no actual dedicated “rest time”) would be perceived as an almost insignificant additional time commitment since it only takes like 30 seconds to bust out a set.
Is this a dumb idea? It seems like it would allow for greater total volume as well. On the other hand I wonder if there’s some “per session volume threshold” that it might fall short of, or if there’s some other drawback to hours-long rest periods.
Eric Helms says
Thanks, glad you found it helpful! The main downside to resting too long, is it just makes training longer with no real upside. Mechanistically, vs practically, I could see resting too long being a problem if you got to the point of actually “cooling down”. But it would have to be pretty long, I’d not go past 5-7 minutes between sets for example. But yeah, like a 5RM on a squat or a deadlift, in someone who’s really strong (and maybe not in great shape), that person might need that long to rest, but I wouldn’t go beyond it.
As to your question, nothing wrong with doing that, as I don’t think there is a per session minimum volume threshold; just doesn’t make sense physiologically. There may be a per session minimum volume for motor development to be effective…like can you really get much out of a learning a movement if you just do 1 rep, once per week? Hard to reinforce the motor pattern. But a minimum for hypertrophy, I dont think so. We are constantly under load living on earth in a gravity well and that produces a constant stimulus and a given amount of hypertrophy proportionate to your activity level. To grow more, we have to increase the load and volume of that stimulus which tells me it’s probably additive in general.
In your specific question, I would be more concerned with HOW you are setting up the accessory sets throughout the day. If you did them in a row, as a series of sets, the cumulative fatigue would keep peripheral fatigue high after the first set and thus motor recruitment high as well. Thus, you’d get a good training effect, and since they’re single joint accessory work like curls and laterals, which doesn’t recruit a lot of tissue and won’t produce global metabolic fatigue, this would have a low risk of any central fatigue. So resting 60s between 3 sets of lateral raises for example, would take maybe 5 minutes in total to do all three sets. However, if you did a set at 3pm, 4pm, and 5pm, there would be no peripheral fatigue to keep recruitment high in sets 2 and 3, so you’d have to make sure each of those sets at 3, 4, and 5pm were hard, and pretty close to failure. If you viewed them as “just volume” without bringing some focus and intensity, you’d probably get less out of spreading them out hours a part vs doing them in a series, because peripheral fatigue would make the subsequent sets a bit more stimulative. Hopefully that makes sense.
Do you think every mini myo-reps series can be counted as a normal series if we keep the load higher than 30% RM and minimum 5 reps? Will every mini series count as a regular series then?
Eric Helms says
Andrew, to be clear, a set of 5 reps with 30% of 1RM will do nothing for you in isolation. That’s probably 40 reps short of failure. Sets that are near enough to failure (0-5 reps or so from failure), that are at least 30-40% of 1RM, and that last at least 5-6 reps long are stimulative. So if you did drop sets or rest pause sets and because of peripheral fatigue from previous sets, you could only do 5-6 reps with 30% of 1RM, all good, but that isn’t the same as 30% 1RM for 5 reps when fresh. Just saying that to make sure we’re on the same page.
To answer your question, Myo-reps/rest pause sets are effective specifically because the first set – “the activation set” – takes you to a point of high peripheral fatigue, meaning that when you do the next mini-set, you have to recruit more muscle fibers to keep the external load going (to keep doing reps). Your muscles don’t actually know the laod, they don’t know you did a drop set to 50% of 1RM, or that you did a rest pause set but only did 2 reps with 75% of 1RM when normally you could do 15; your muscles are just trying to do work. So long as the way you set it up results in that work being done in the presence of high peripheral vs central fatigue, those reps will recruit muscle fibers that they otherwise wouldn’t be recruited at that low of a load or that few of reps at a given load.
So, how do we count it? That’s a tough one to answer, and it’s the downside to these techniques. I wouldn’t recommend comparing straight sets to drop sets or rest pause sets. I would only compare these approaches to themselves. Comparing volume of straight sets to one another is easy. You’re progressing if you can do more reps or increase load, you’ve added volume if you’ve increased number of sets. Easy. But if you do drop sets or rest pause/myo rep sets, start fresh.
For example, this week if you are doing straight sets and you do 3x8x80% 1RM, that’s fine, but if next week you decide to instead do a drop where you do 10 reps at 80%, then 3-5 reps with 70, 60, and 50% of 1RM in a series of drops…make that a new starting point to progress from. Don’t try to compare that drop set series’ volume to the week you did 3×8. From that point on, just try to progress the load or reps on the drop set series. Same thing with myo reps/drop sets, if you did an activation set of 10 reps at 80% then you did 3 sets of 2-4 with 80% after the activation, don’t compare that to your 3×8, make the myo rep set your baseline, and try to increase load or get a few more reps on your myo rep sets following the initial activation set in the subsequent weeks.
Thanks for the answer. I just mean that whether every mini series that meets the appropriate load and the number of repetitions, e.g. bending a dumbbell for 18kg biceps where my max for 1 repetition is 24 kg, 8 reps + 5 reps + 5 reps will not be as effective as 3 regular series after 8 reps?
Eric Helms says
Andrew, please check out my response again as I specifically addressed comparisons between regular series of sets and drop sets.
Based on the conclusion of this article, I would think that myo / cluster / rest pause sets also should to stay above 5-6 reps after the activation set, which would only be possible for lower intensities. Is that correct?
I can’t remember the details of the studies on cluster sets, but I guess they resulted in less than 5-6 reps after the activation set, but still resulted in similar muscle growth. Myo reps also seem to be done mostly below 5 reps, that’s why I am confused.
Eric Helms says
Check out the part where I cited a rest pause study in which it was compared against traditional sets, outperformed traditional sets, and less than 5-6 reps were performed after the initial set to failure. I also explain why that occurred. If you were thinking a set of less than 5-6 does nothing and doesn’t count, or something like that, that’s not what I’m saying. Hopefully that helps?
While I do not think that sets of less than 5 don’t count, I can’t help but thinking that the recommendation “so long as you don’t drop load below ~30-40% of 1RM or perform less than ~5-6 reps per set, it shouldn’t hinder hypertrophy” means, that when you don’t rest enough between rest pause sets and fall below 5 reps, it hinders hypertrophy, and it would be more effective to keep reps at 5+, so that each rest pause/myo/cluster set has a similar anabolic response as traditional sets.
That’s my conclusion, but I am not sure if my thought process is correct, since you did not directly recommended to keep the reps at 5+ for rest pause/myo/cluster sets.
Eric Helms says
You’re trying to make an apples to oranges comparison, and I think you’re focusing too much on the recommendation without understanding why I made it. That recommendation is for straight sets specifically. A set of sufficient effort, that lasts sufficiently long, that is sufficiently heavy can be compared to another set that meets that criteria. That recommendation is not for a myo rep/rest pause set. We don’t have sufficient data to make such a comparison between straight sets and drop sets or rest pause sets which is why I’m telling you not to try to do it. Again, in the article, 3x6x80% was inferior to doing a set of 80% to failure followed by multiple rest pauses that were likely less than 5-6 reps, to equal 18 total reps when added to the initial set. So clearly avoiding rest pause sets of less than 5-6 reps isn’t a logical thing to do and it’s not the way you likely would count things. Again, don’t compare drop or rest pause sets against straight sets. The way that would make logical sense to count volume in a rest pause set would be to count reps after the activation set, and just try to progress from there. The initial activation set is a straight set, but the additional reps will achieve high activation because of the fatigue from that first set so they will likely all “count” to some degree. How much? We don’t know. How do they compare to straight sets? We don’t know. So again, don’t try to compare apples to oranges, I mean you can, but it’s a guess.
I understand now, for some reason I missed the fact that the sets after the activation set are different from straight sets and tried to apply the recommendations for all sets.
Thank you for answering all my questions!
Eric Helms says
AMAN WALIA says
Couldn’t be put down in a better way. Thank you for this!
Thank you Eric, that was a fantastic article!
There is however one thing that I don’t understand: When training to failure on all sets, it is still easily possible to follow the rules of your conclusion
“..at least ~5-6 reps, above ~30-40% of 1RM, at a sufficient proximity to muscle failure, so long as reductions in reps and load are primarily due to local rather than central fatigue”.
When following those rules, each set to failure should be equally effective for muscle growth as each set just close to failure with some reps in reserve, but the research / recommendation is to not go to failure.
What am I missing?
Eric Helms says
You might not be missing anything, or maybe if anything I think your missing the last part of what you just quoted “so long as reductions in reps and load are primarily due to local rather than central fatigue”
As I mentioned in the article, the study by Schoenfeld had the participants go to failure on a fullbody mostly compounds program and the short rest group grew way less. So failure is more problematic with short rest periods than long as more acute cardiometabolic fatigue accumulates. But failure with sufficient rest and not too high volume isn’t that bad. Some data suggests failure regardless of rest period is a bit worse for strength, but probably more so with higher volumes or frequency as it elongates recovery time for force production. For hypertrophy there is some data it could be worse for more advanced lifters, but overall the data is mixed. In the end, failure is a viable way to train if you account for the additional recovery demands, although it does limit your other options (frequency and volume).
How much volume would you recommend for a beginner/intermiediate.
How many Myo-rep sets per muscle per week should i approach? Myo-reps done after strengthtraining.
I train at home with only a barbell, powerrack and some dumbbells.
You consider doing Myo-reps only for isolate excercises.
exp. Can i do 2 Myo-rep sets of DB bench press after my strength bench press twice a week?
This would be a total of 4 Myo-rep sets per week.
great article btw, this stuff is OD
Eric Helms says
Thanks! And check out the products tab and the Muscle and Strength Pyramids link, these are my and my coauthors books that go into how to program.
Great Information 🙂 Do you think a program consisting of cluster sets only (like 1 activation set, followed by about 10-15 reps as clusters for each exercise) would be as good for muscle growth as a few straight sets per exercise? It would save a lot of time
Eric Helms says
Thanks Ben! Check out my responses to John’s questions/comments I cover this there.
Joanne Cugnet says
Thank you. It explains why when I do unilateral dumbbell overhead press it is easier than when I do it with arms simultaneously. Not the only takeaway that I had but one that made total sense to me. And yes I do her you talking as you write:) Thanks Eric! You have a heart of gold, Jo
Forgive me if I missed something, but what kind of fatigue is occurring during repetitive, 1 RM efforts? For example, during a pre-competition cycle, I will repeatedly hit singles at 90%+ on the snatch and clean & jerk. As the training session continues, I start to miss more lifts due to fatigue. I am absolutely fried after such training, and I’ve always considered that fatigue to be central. From what I just read, it seems that central fatigue is mostly caused from accumulated cardio-metabolic fatigue, which doesn’t happen from 1RMs (at least not to the extent of high-rep leg press sets w/ minimal rest). It doesn’t seem that peripheral fatigue would be occurring either, as there are minimal metabolic byproducts with 1RMS.
Am I still “training the nervous system” with these heavy singles? What kind of fatigue am I experiencing? Thank you! Great read, and great listen on Iron Culture.
Eric Helms says
Marten, that is a fantastic question, and you didn’t miss anything. Rather, this is just not something I directly addressed in this article. It’s not that central fatigue can’t come from heavy work, but rather, that just hasn’t been explored all that well. However, it is established that central fatigue can manifest from cardiometabolic fatigue creating a feedback loop, initiating central fatigue.
I certainly think there is something to what lifters describe as “CNS burnout”, exactly as you are describing. Right now, all we really know is what it probably is not, and it’s probably not central fatigue mediated by cardiometabolic fatigue, and it’s probably not muscle damage. That said, if you look at the overtraining research https://www.jsams.org/article/S1440-2440(19)30999-5/fulltext frequent high intensity “monotonous” (referring to varying loads and volumes not exercises) training is what most consistently is related to symptoms of overtraining.
I think part of this is related to the mental exhaustion from maintaining the focus and arousal required to train in such a way, but this hasn’t been well explored.
Very interesting – do you think there is an argument against full-body workouts then because of the larger amounts of muscle-mass it involves and thus the greatel potential to induce central fatigue which could then limit local recruitment?
Eric Helms says
its definitely an argument against short rest intervals and training to failure on compound lifts as a part of a full body routine, but that would apply to a leg day as well for example
This was an excellent read, so many valuable takeaways! A point that I’m curious about is whether or not there may be an increased risk of injury as a result of the central fatigue generated from shorter rest periods. I imagine this would be tricky to study.
Eric Helms says
Acute fatigue (central or otherwise) can contribute to injury risk on high velocity skilled movements, especially involving change of direction, high force absorption and other sporting movements, so it could be plausible for things like Olympic lifts, or ballistic training but probably not nearly as much for bodybuilding style training, maybe to a slight degree for compound free weight lower body exercises. Which is probably another reason not to do high rep, limited rest, to failure training styles regularly for squats/deads for example. But in general not something to worry about in the context of lifting
Hi Eric, after reading and digesting this great article I came up with the following rule of thumb for determining load, reps and rest for each exercise. First, I rest as long as I need between sets so I don’t feel out of breath (think I picked up this tip from Mike Israetel). Then I use whichever load allows me to get at least 6 reps on every set. So for example with squats, I need 2-2.5 minutes rest, but this allows me to use a heavy load and still maintain reps, so I do 6/6/6 with ~8 RM. With curls, I only need 30-45s rest, but due to the local fatigue I can’t maintain reps so I use a lighter load and do something like 14/9/6 reps with ~15 RM. Any thoughts on method?
Eric Helms says
Alex, sounds like you’re on track, but remember there’s nothing magical about six reps, really the crux of the article is that you want local rather than central mechanisms to cause fatigue. The example you gave is great though, as squats are the more globally fatiguing exercise likely to cause central fatigue than curls, so it’s a great way to set it up.
Ryan Cherry says
Back on the comments again…loved this article! As a busy father of twin boys, I find antagonist supersets and myo reps (or even drop sets) useful as time saving strategies to maintain volume or rest times while also saving time. I love watching Berto demonstrate employing clusters into his training (especially love the upper body video with Jeff Nippard).
I have a split question in terms of antagonist supersets. I’ve listened to and read about your take on frequency as a vehicle for higher volumes. I also have the Lifting Library and love it for practical programming strategies. My question is, as a casual or recreational lifter who typically sticks in the 12-16 set range for major muscle groups (depending on individual muscle group needs) is there anything wrong with running a 2x a week frequency in the form of a Arnold Split/Upper Lower Hybrid, for example:
Day 1: Chest/Back
Day 2: Shoulders/Arms
Day 3: Legs
Day 4: Rest
Day 5: Upper
Day 6: Lower
Day 7: Rest
I’ve always loved the arnold style antagonist superset style but wondered if it was okay to hit shoulders and arms the day after chest and back. Hearing your take on hitting muscles on consecutive days made me think that is potentially okay (though volume isn’t distribute as much throughout the week as the full body approach), taking into consideration smart exercise selection for presses falling on consecutive days for front delta and triceps. Anyway, I just love this style way more the ULPPL and find that I like more focus on each day rather than an ULULU 5 day set up. Granted I realize there is more to be considered with every individual. Sorry for the long winded comment that is semi connected to this article…just appreciate all your content and you as a communicator! Love the cult too #ironculture
Eric Helms says
Ryan it’s a great split! That said, I do think you’ll probably be a little fresher for your sessions if just swap Day 2 & 3. That way you always have at least a day off/hitting a different muscle group before hitting the same muscle groups again. Good luck!
Ryan Cherry says
Should I be concerned about shoulder and arm training being close in the middle of the week that way with only a day in between? Or am I overthinking it? So you mean:
So arms would be separated by a day. I guess you could say there is indirect work on chest and back too. I suppose I could shift some upper isolation to legs to balance it more? Sorry if that is a silly question!
Ryan Cherry says
Maybe I’m overthinking the spacing things out. So I’m not waiting too many days to hit shoulders or arms again? Which ends up being 4 days until direct training again on the tail end. Or does it only matter that I’m still at least training each muscle group directly 2x a week, aside how they are separated? Cognitive dissonance here lol 🧠😬
You could swap the UL at the end to LU.
48 hrs between arms on day 1 and 3 then another 72 hrs between day 3 and 6. Plus legs get a 72 hr break too
Eric, you have a gift for teaching. Even I got it after two read throughs. You’re a miracle worker!