Light VS Heavy Weights: What Builds More Muscle?

Foreign.

What's going on, everybody? And welcome back to the Filth the Science podcast. You're here with your host, as always, of course, me, myself and I, that is Max Coleman, AKA Coleman, et al. And sitting in front of me as tradition, as always, as per usual, Daniel Plotkin, AKA Danny Boy. AKA Danny Boy. AKA Danny Boy. And today we're going to be talking about heavy versus light load training for muscle growth, questioning the age old notion of train big to get big, lift big to get big. We're going to be talking about why we once believed that you needed to leave lift heavy in order to grow muscle. And then we're going to talk about some of the research that came out that started questioning that idea. And then we're going to talk about maybe there is some grain of truth to the notion of you can train a little bit too light, but there's also a little bit of truth to the aspect of you can train a little bit too heavy. And then we're going to give our practical takeaways for what general rep ranges you're probably going to want to stay in if you want to maximize muscle growth. But before we do any of that, Danny Boy, why don't you go ahead and tell us why we once believed that you had to lift big to get big.

Yeah. So I don't know if you noticed, but you glitched there. You said my nickname three times in the same exact way. So it was pointed.

It was. It was.

So, yeah. So why did we once believe that high loads are necessary in order to maximize growth? It seems like it's mostly a combination of Brolor and some EMG data. So the Brolor and even some scientists who, let's face it, a lot of the scientists who get into this space definitely have, you know, some real mentalities coming into it, believe that in order to stimulate those high threshold motor units, those motor units and associated muscle fibers that are most likely to grow, we needed to use higher loads. And there was just, you know, some reasonable speculation that once you get super high up in rep ranges, it's more akin to endurance training. And then some evidence from EMG data showing that you get lower amplitudes from lower loads. So based on that weak line of evidence, people were like, yeah, just to be on the safe side, it makes sense to do most of your training at higher loads. Which at the time was seemingly a pretty good recommendation. And honestly, even now, not the worst recommendation. But as we'll get into later on, we have a lot more data now and there's A much wider range.

Yeah, I mean we're basically going to get at the end of this because like the idea for a long time was like 1 to 5 or maybe it was like 1 to 3 was strength, 6 to 12 was hypertrophy and then 15 plus was muscular endurance. And we're basically going to talk about why. We kind of still think that 8 to 12 is probably where you want to spend most of your time anyway. But we're going to draw it out and make you guys listen to us for an entire hour before we tell you why that's actually the case. So yeah, for a long time. Excuse me. For a long time we thought that you had to absolutely lift heavy or at least within below like let's say 10 reps, you know, if you wanted to grow muscle and anything more was glorified cardio.

Right.

But then I believe, and you can correct me if I'm wrong, Danny Boy. In 2012, a study came out of Stu Phillips's lab out in Canada, shout out D money showing that it had untrained subjects, lifting, doing leg extensions, it might have been within subject, even doing heavy versus light leg extensions, showing similar growth between legs. And so that was the. And or between participants. I can't remember if it was within subjects or not, but it doesn't matter. That was the first study, at least to my knowledge, that showed, okay, maybe we can still grow muscle with light weights. But it lets, I mean some, some people were like, oh, they're untrained subjects. Untrained subjects grow from walking and cycling. So that's really not, that doesn't throw a whole lot of credence to the idea that you can gain muscle through a spectrum of rep ranges.

Right. But.

Sorry again, more and more evidence since then has come out showing that even within trained subjects, even within older individuals, younger individuals, across a wide spectrum, males, females, of populations, that both low load and high load training can result in similar muscle growth. So I believe the second one, not super sure about this, came from Dr. Schoenfeld, Danny Boy and I's former mentor from Lehman College in our master's program. He did his dissertation on high load versus low load training looking at individuals performing either 7 sets of 3 repetitions or 3 sets of 10 repetitions and also showed similar growth between individuals. And there's some issues there. Obviously that's more sets resulting in similar growth, but it at least shows that individuals can grow muscle through a somewhat wide variety of rep ranges. And then more and more studies that Danny Boy, I'm sure you have more DOIs and PMIDs locked in the back of your head that you can touch on, just showing essentially that both low load and high load training can result in similar growth.

Right.

There's even one study. Oftentimes the recommendation is anywhere from 30% of 1 RM to 85% of 1 RM is like a safe bet. We now have enough evidence to suggest that if you're within that spectrum of 1 RM, that spectrum of rep range, which can really extend anywhere from like 5 reps per set to 50 reps per set, generally 30 is the one that people often throw out.

Right.

But we have enough evidence to suggest that if you're within that general range, you can be pretty confident that you're going to build muscle, assuming that you're training to failure. Now there is some evidence to suggest that you can go too light, that even if you're trained to failure, if you're not using a sufficient enough load, you can result in perturbed muscle growth. Danny boy, you want to touch on that a little bit or is there anything else that you want to say with regards to my 10 minute word vomiting that I just did?

Yeah, I think we'll get into the details anyways, so let's start light and then we'll go heavy. So the question was whether it's possible to go too light in the gym. And I think the answer to that is seemingly yes. So we have two studies that point in that direction. Jesse et al and Ozaki et al.

I believe no. Ozaki is in defense of light training.

We have two studies on the topic, but Jesse points toward the fact that you can go too light while Ozaki sort of questions that. So not a whole lot of strong evidence or not a whole lot of evidence in general on that front, but some evidence pointing into, into the direction that once you go above 50, you're probably in the territory of not maximizing, maximizing growth, but definitely still growing. And we'll also get into. After you go over the, maybe some of the findings of the Ozaki paper, why practically speaking, it's probably not the best idea to do most of your sets above the 50 number.

Yeah, now that I'm thinking about it, I'm wondering if too light is a thing like the Ozaki paper had individuals start with 30% of their 1 RM for some. So this study was comparing high load training versus low load training versus drop sets.

Right.

And individuals had their arms randomly assigned to one of those three groups. And so within subject, very powerful design here.

Right.

And they. So in the low load group, they never increased load throughout. They kept it seemingly at least it's hard to find throughout the paper. It seems like they kept loading consistent throughout and just increase reps throughout the course of the study. And eventually the average number of repetitions that you saw in the low load group was a hundred repetitions on the first set and 40 on the second and 30 on the, on the third.

Right.

But they were training to failure concentric muscle failure and seeing the same exact muscle growth as the high load and the drop set group.

Right.

However, we, we, we just touched on this Danny Boy and I didn't really think about it until right now. Danny Boy and I spent like a good hour and a half talking about this podcast before actually starting recording, which was silly. But in the Jesse paper they stopped the sets at 90 reps no matter what.

Right.

Because just for some theoretical basis and.

That happened too often. So I get where you're going with this that like because they stopped the sets, maybe the fact that they didn't go to close or two concentric failure, that created a discrepancy, but I'm just not sure how often that occurred. So I don't think we can say with confidence that the reason why the Jesse paper leaned in favor of the 70% group or the higher load group is because of the fact that they didn't take all sets to failure in the lower load group. But I definitely get where you're coming from.

So. And I don't want to go back and forth too far in the, on the minutiae of it, but if the, the ozaki paper was 31 RM and they were doing on average across the duration of the study, a hundred Reps on the first set and the Jesse paper was 15% of 1 RM and they stopped them at 90 reps, it wouldn't be shocking to me at the very least that they, it happened relatively often that they were hitting 90 reps. Maybe I have no idea because they didn't present an average number of repetitions they did per set. They just said at most 90 and they cut it off if they went above 90. So it's certainly possible the study with a better design shows no difference is is all that it points to. So maybe there is too light. There is certainly a too light from a pragmatic standpoint and we'll get into that later. But the evidence doesn't necessarily point to that. And then you can even do certain things like BFR training for instance, where you're using very low loads, potentially even less than 30%. But again, speculation there all of this to say is that there probably is some reason to believe that you can go too light with respect to training. But hopefully the majority of the people listening to this podcast wouldn't be going that light anyway, because you're not going to want to be doing anywhere from 50 to 100 sets a set for a lot of reasons. One, it's it hurts like a. Two, it takes a lot of time. And then three, for reasons we'll get into later, it's kind of harder to tell if you're close to failure when you're doing sets of such a high number.

Right.

But do you have anything else you want to say about maybe going too light?

Yeah. So I think just to add on to the likelihood of you being very close to failure, I think the probability that somebody gauges proximity to failure accurately when there's a research assistant standing there, you know, egging them on, is much higher than in the gym where you don't have somebody motivating you constantly. So I think just from a practical standpoint, the likelihood that you'll gauge it is lower even probably in a. And that's, I think been shown a.

Few times that it's lower even in a research setting.

Exactly. Yeah. And then that's probably compounded with just a regular gym setting.

Yeah.

Because we do have some evidence to suggest that supervision during resistance training leads to hypertrophy. Okay. Anything else you want to say about too light before we move on to potentially, is there such thing as too heavy?

I think that's good.

Yep. All right.

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Well, then let's talk about if things can be a little bit too heavy. So again, not super clear evidence with respect to if things can be too light, but there's actually more. It's funny actually, if the. If the original bro science notion was you have to lift big, you have to lift big to get big, and now we have so much evidence on the topic, very little, very little evidence points to too light being a problem, but we do have some evidence pointing to too heavy. Being a problem. Do you want to touch on some of those studies?

Yeah. So one of them you touched upon doesn't really directly get at this question, but sort of in a roundabout way gets at this question where Brad's dissertation looked at either 3 sets of 10 reps or 7 sets of 3 reps. So since they found no differences in growth, you could say that 3 sets of 10 reps is at least more time efficient than doing 7 sets of 3 reps. So you can get more from less sets, presumably, but more from less time.

And on a set per set basis, like all in all.

Yeah. So you could start drawing weak conclusions from that. But ideally you would look at them head to head with same set number. And that's also been done by a later study by Brad. So they found that doing between two and four reps. And what was the higher is it. Was it.

It's 8 to 12 versus 2 to 4. And then he does have one that's like. Yeah, 20. It's like 8 to 12 versus 25 to 35 or something like that. Those showed no differences.

But those are different studies. Yeah, yeah, yeah, exactly. So but in the study that compared 2 to 4 versus like 8 to 12 there, even though I believe the differences weren't statistically significant, they did heavily favor.

Yeah, the effect sizes were very largely in favor of the moderate load, which was 8 to 12, as opposed to 2 to 4, even though it didn't reach.

Yeah, just, you know, obviously not something that we are going to put too much stock in. So. Yeah, two studies. One more strongly pointing toward the fact that you can go too heavy and one sort of in a roundabout way pointing toward the fact that you can go too heavy. So it seems like the Burls were pretty wrong on this one. So can. What can you do, folks? You know, sometimes the OG bodybuilders were not on the money.

Yeah. But when they're right out of one out of every 10 times, it's hard evidence that the bros knew what they were talking about all along.

Right.

So if you just flip a coin.

I, I always, you know, that's true. Yeah, it's a good point. Like the null hypothesis is almost always true in, in this field. It's like, like there's almost never actual differences between groups in these studies. Sorry, big lame ass tangent for Danny boy and I get on. But yeah, so this whole podcast could boil down to. Look, don't. You don't need to lift big to get big. And in certain instances you can go way too big and it's going to actually interfere with your ability to grow muscle. However, now let's talk about some actual practical takeaways from this. Like, given that you can grow muscle clearly from anywhere doing as little as five reps to seemingly doing even a hundred reps per set, where do you think that we should spend most of our time training? And why do you think that?

Yeah, so I think before we jump into that, let's maybe talk about since we did the same thing for light loads, why practically speaking, going less than 5 wouldn't make much sense.

Yeah, yeah, yeah.

Super heavy loads. Yeah. So I think the biggest reason by far is just is very heavy. So one, you need to probably do maybe a little bit more warming up to get to those heavy loads with, you know, three reps, two reps and so on. So even if it did produce the same growth, which as we know, there's some evidence showing that it does not produce the same growth warming up to that amount, the amount of focus that you need at that amount. And in Brad's, both anecdotally and in Brad's seven by three study, seven sets of three reps, people were complaining about, about joint pain and they weren't enjoying themselves too much when they were doing lots of sets at lower rep range. So I think practically speaking, to layer on top of the fact that we have some evidence pointing the direction of it's not as good for apertrophy, you probably want to stick to above 5. So just to put a cherry on that, but then getting into practical takeaways and which rep ranges we want to generally be at, I think most of your training should be within the 8 to 12 rep range and probably the 5 to 15 rep range just to have a wider array for different exercises. So for compound lifts, typically I like to be within the 5 to maybe 12 range. So that way I can be not limited by my cardiovascular system, not limited by other muscles that need to maintain my posture. And for isolation movements, I usually probably don't want to do around five, even though it'd probably be okay because of the fact that, you know, things tend to feel smoother on a lateral raise or a bicep curl or a tricep push down when I'm not doing, you know, very heavy loads. Could you do it?

Sure.

And if you feel fine doing it, definitely have at it. But anecdotally, some people tend to have a little bit more joint issues and find a better groove at that more moderate to even high, highish rep range where it's you know, closer to 12 to 15 and even up to 20 to 25 on those isolation movements. So I think 5 to 15, you have a whole lot of wiggle room where you can keep some exercises, mostly compounds in the 5 to 8, then most of your exercises around the 8 to 12, and then some of those isolation movements in the 12 to 15 range. And I think that would practically cover a lot of bases while also traversing a wide array of reps where you can maybe pick up some potential different mechanisms and things like that as well.

Yeah, the reason that I didn't. Yeah, yeah. If. If it exists. Very big if there, but very potential if at the same time, in my opinion. So, yeah, the reason I didn't get. So the reason I was giving practical takeaways for too light is because we don't have empirical reasons why you shouldn't go too light, really. But we have direct, empirical reasons why you probably shouldn't go too heavy. Because there's like inherently outside of. Of practical or the pragmatic side of lifting, it inherently affects growth.

Right.

But yes, there are also really good practical reasons why you shouldn't go too heavy as well. One, it fucking hurts. Like, no. No question about it. And even we have some loose data, like the injury rates per 10,000 hours for, like, power lifters are higher than bodybuilders.

Right.

Is that because they're lifting heavier? Maybe. We're not exactly sure, but it's one of the biggest differences between powerlifters and bodybuilders is the rep ranges by which they operate in.

Right.

A lot of bodybuilders are doing squat, bench and deadlifts.

Right.

But just to be clear, those numbers are very low for both.

For sure. Yeah, yeah, for sure.

Yeah. I just. I know, you know that. I just wanted to make sure people weren't like, oh, man, I'm gonna get.

Injured as a. I don't. Power lift. Yeah, no, Powerlifting is still safer than like football or basketball or even like gymnastics, I believe, from. From an injury perspective.

Sheer gymnastics.

Yeah, yeah, yeah. So anyway, yeah, practical reasons. Danny Boyle kind of really summed that up super well right there. But there's a lot of good reasons to stick into the 8 to 12 rep range.

Right.

1 or. Or 5 to 15, regardless. Anyway, just normal, like, moderately, what we call moderate load training.

Right.

And I think that one thing that's really important, you basically touch on this, but I just want to say it explicitly is that exercise, like loads that you choose oftentimes will be predicated on these specific exercises. That you're doing. So like Danny Boy was saying, like dude, I'm not doing a lateral race set for like five to six reps. I'm literally only going to feel that in my rotator cuff and I'm not going to. My delts aren't going to feel like a thing. And I don't necessarily care how your muscles feel during an exercise, but if you're experiencing pain, it's probably not a good, good thing to do. And then conversely like I'm not going to be doing squats in the 20 to 25 rep range either because I like, I can barely go up a flight of stairs without being out of breath, let alone do something like that.

Right.

It's going to, I'm going to be limited by my inability to breathe than I am my ability, my like quads inability to continue producing force.

Right.

So I think that, I think Brad said this on, on other Revive Stronger podcast or something like that, but he basically said I keep almost all of my training in the 8 to 12 rep range and then I like 75% of all of my training in the 8 to 12 is rep range and then sprinkle like 25% a little bit lower to like the 5 to 6 and like another couple of percentage to like the 15 to 25 to 30 is rep range. Like Danny Boy said, very loose, very limited evidence to suggest that there might be something additionally hypertrophic like compound, like there might be some compound hypertrophy that happens as a result of doing heavy and light load training. Because maybe there's some sort of specific hyp. Specific hypertrophic mechanism in the heavier loads and some other specific hypertrophic mechanism in the lighter loads that results in differential type 1 versus type 2, whatever fiber growth. But that's very loose. And we're only saying that as a. If you want to be sure that you're checking every single box that you can to make sure you're growing as much as you can, it's probably a good idea to lift through a very wide array of ranges. But you can be very confident if you stick. If you do everything in the 8 to 12, you can be very confident that you're checking the majority of your boxes or 5 to 15 to quote any, because one, they're just more time efficient. Generally speaking, you can be a little bit more confident in your proximity failure and it lends itself to most exercises. Because I don't mind doing squats for a set of five and I certainly don't mind doing a set of bicep curls or tricep extensions for a set of 15. Right, cool. This was like probably one of the fastest episodes we've ever done. I think we've covered it pretty well. Do you have any tie together thoughts or anything you want to say about what I said?

Yeah, I think there's a bit to add there. So I think even if it doesn't matter for fiber type specific differences, there could just be different mechanisms going on even for the same fiber type. So I think that's one thing I wanted to mention. Another is that to talk a little bit about the higher rep ranges, there is some evidence that you need to go closer to failure at those higher rep ranges in order to get all of the benefits. So that is something that I think we failed to mention earlier. While it doesn't really matter too much from a practical standpoint because you still. We're still going to be in the 5 to 15 range practically. That's another reason why we may want to veer away from, from those very high rep ranges. And I think one thing that's super important that we would need to touch on from a practical standpoint that we didn't yet is I think monotony is something that people don't talk about a lot with training. But being able to traverse 5 to 15 for one exercise is something that motivates me a lot in that if an exercise is starting to become stale and I don't necessarily want to take it out because I really like the exercise. Having something where you can consistently get wins, even if it's from a psychological standpoint just by switching that rep range from like, you know, around 8 to more around, you know, 12 or 13 can have a lot of, if not for anything else, psychological benefits, which makes me more motivated to do the exercise and keep on pushing those numbers. I think that's worth it just from that standpoint. So breaking a monotony for the same exercise is I think a super valid reason. And even for obviously potential physiological reasons, but just the psychological reason alone I think is enough to validate that.

I think it's a really. Yeah, that's a great point. It's something I like to do as well. Now we're kind of talking like bros at this point, but it's something I really like to do in my own programming, is that I. There are certain exercises that just click really well for me, like overhead dumbbell tricep extensions just give me the sickest, most gnarly tricep pump ever. And there's a Good reason to believe it's a really good exercise. Right. Good empirical reasons to believe it's a really good exercise.

Right.

So what I like to do is because I don't want to perform the exact same exercise twice a week, I'll do on Monday, let's say overhead dumbbell tricep extensions, 3 by 5 to 10. And then on Friday, later that week, I'll do the exact same exercise, but 3 by 15 to 20. That way I'm not worried about having to beat myself for Monday or anything like that. And it's just the same exact exercise, but it's fun. Like, it's fun. It's like a different stimulus almost to a certain extent. And when you've been in the game for so long, you have to find really silly, stupid ways of making training fun for you, whatever those might be.

Right.

So, yeah, I think that was a really beautiful point, dude.

Anything else? Yeah, I do the same thing for like, leg extensions, for example. I think hitting the rec fin makes a whole lot of sense. There's not a whole lot of exercises to choose from for certain muscle groups, honestly. So varying rep ranges for that, just from a psychological standpoint, makes a whole lot of sense. I do the same thing with drop sets. I'll have one regular straight set day and then a drop set day where I can, you know, be motivated by beating the drop as opposed to beating the load and so on. Like beating the rep number.

Yeah. Cool.

Anything else you want to say before I tie this? Tie a bell on this bad boy.

I think that's good.

All right, sweet. Okay, so thank you guys so much for listening. Just to tie this all together, we did once believe that you had to lift big to get big, based on some loose speculation of the Henman size principle, as well as some EMG data that we had.

Right.

However, we then had more and more studies come out suggesting that light versus heavy load training kind of produced similar results. Assuming that you're staying within a General Percentage of 1 RM between 30 and like 85%.

Right.

Which generally equates to somewhere between 5 and 30 repetitions.

Right.

Not a whole lot of evidence suggesting that you can go too light, but a lot of really good practical reasons why you probably don't want to, and definitely some empirical evidence suggesting that you can go too heavy and that'll actually in of itself result in less growth.

Right.

However, big practical takeaway, spend the majority of your time in the 5 to 15 rep range with 5 being used. The. The general closer to 5 being used more often for things like squats, RDLS, bench pressing, things like compound movements and things closer to 15 for your isolation movements like lateral raises, bicep curls, calf raises, and stuff like that. Plus, don't be afraid to and don't ignore higher rep ranges in the like 15 to 30 ish rep range, because there might be some special benefits to doing that on top. Maybe some additive hypertrophy that we'll get on top of doing traditional training.

Right? All good.

Perfect.

Sweet. So it looks like the bros were kind of right all along. 8 to 12 is your hypertrophy your best hypertrophy rep range? All right, thank you all so much for listening to the Built With Science podcast. If we have a topic that we haven't covered yet, please feel free to reach out to us at Built With Science on Instagram. And as always, thank you so much for listening.

Peace.