Ep. #237: Research Review: Dr. Mike Zourdos on Blood Flow Restriction Training

BFR produces comparable hypertrophy to heavier training but less strength gain

The systematic review shows BFR at 20-30% of 1RM produces significant hypertrophy similar to other training methods but less strength gain because BFR does not train neuromuscular adaptation.

"It's pretty clear that blood flow restriction training does increase strength and it does increase hypertrophy. It's also clear that blood flow restriction training at 20 to 30% of 1RM doesn't increase strength as much as training at a higher load without blood flow restriction training."

Apply BFR wraps at 6-7 out of 10 tightness for safe and effective use

The tightness of the wrap is critical for safety. A 6-7 on a 1-10 scale is optimal. If you tie the wrap and cannot stand up, it is too tight. You want to restrict blood flow, not occlude it entirely.

"Proximal meaning close to, but proximal meaning above. So rather than distal, which would mean below. So if you have the upper part of your leg, you have your thigh, you would tie, if you want to work anything on the lower body, you would tie the knee wrap for blood flow restriction training at the top of the thigh. So just as if you wanted to exercise your biceps, you would tie the knee wrap. In this case, you might use an ACE bandage or something that's a little bit smaller because the upper body muscles are smaller. And you would tie that proximal or above your bicep. So kind of just below your shoulder there. Restricting blood flow to it. Because if you go below, you're not restricting blood flow. Exactly. Hence the name. And so... I just looked in the dictionary. So proximal, situated near to the center of the body or point of attachment. Hey, learn a new word. There you go. See, you know? To be fair, I've actually cleared that word to dictionary before, but it didn't come back to me properly. Brain fail. You know, we got it, man. But, you know, I know that word and some other things because we're talking about an area that I'm interested in. But you have me on the podcast and we want to talk about something that doesn't have to do with exercise science. I'm in deep, deep trouble. So, you know, I only know what I kind of do for a living. So, but in 2008, 2009, I was doing that. And I would go into the gym and do squats with this or do curls with this, whatever it might be. And I would have people come up to me and they would say things like, hey, man, you know you're not using those right. Or what are you doing? Or are you trying to have a heart attack? And the countless times that somebody came up to me unprovoked in the gym and to try to question me on what I was doing, it was pretty crazy back then, you know, 10 years ago when really nobody knew about it. There were only a few people researching it and it was really new. And so then I would calmly try to explain what it was. And not a whole lot of people were willing to listen. There were a couple people. I remember I got one person to listen and he actually did it in the gym with me that one day, some random dude. And it was pretty fun. But a lot of people weren't willing to listen back then, and they thought I was a crazy person or had no idea what I was doing. And I probably didn't really know what I was doing back then. But I was trying to do blood flow restriction or occlusion training. But it's amazing to see how far it's come over the past 10 years. And I don't know if it's mainstream yet, but it's definitely out there much, much more, and it's talked about a lot more. So it's pretty cool. But nonetheless, that's the basis of how you would apply blood flow restriction. So the study we're looking at here is actually a systematic review. And a systematic review is kind of a review paper that has strict guidelines for how it searches other papers. And then it reviews all of the other papers that are in that area based upon its guidelines to kind of give an overarching recommendation, if you will. Is this a good idea? Is this not a good idea? What are the overall findings? So it's similar to a meta-analysis, but it doesn't run as many in-depth statistics as a meta-analysis. So we can't quite call it that. So for a systematic review here, this wanted to look at the efficacy and safety of blood flow restriction. So for the efficacy, kind of how the results are for hypertrophy and strength. So there are a few things to keep in mind here when looking at this, which is that blood flow restriction is compared in two different ways to other training modalities most commonly. One, it's compared to high load training, and then also compared to low load training. And now when we talk about using blood flow restriction training, when you're using that knee wrap, and you're let's say you're using using that knee wrap on the lower body, and then you're you're restricting blood flow, and then you're squatting. Typically, you only need to squat with about 20 to 30% of 1RM. And that applies to all exercises. So if you were to do a leg extension, 20 to 30% of 1RM, and obviously, you're most likely not going to know your 1RM leg extension. But the point is, you can take a very, very light load and utilize blood flow restriction training. So what the systematic review shows is that it's pretty clear that blood flow restriction training does increase strength, and it does increase hypertrophy. It's also clear that blood flow restriction training at 20 to 30% of 1RM doesn't increase strength as much as training at a higher load without blood flow restriction training. And I think that's pretty logical because if you can understand the mechanisms by which strength occurs, strength can occur via hypertrophy, meaning as muscle size increases, that should play some role in the long term in muscle strength. But strength also increases from a neuromuscular perspective or an efficiency perspective. And this is really illustrated that if you think back to the first time you ever bench press, right? In any male's life, the first time they ever bench press, they probably can remember it. I know I do. And I was in eighth grade and I benched 65 pounds. And I pretty much thought I was the strongest person in the world. I remember the bar path on the bench. If you can remember back to when you bench press at first, it wasn't a straight bar path. It probably one side went up more than the other. It kind of teetered around a little bit. Then you finally were able to lock out that lift. And then the next time you did it, it was better and better and better. Then ultimately, not only were you stronger, but you had a straighter bar path and the movement was more fluid. That's with any skill, right? That's looking at a skill or a neuromuscular adaptation. So at high loads, if you want to increase your 1RM, you're going to get much better neuromuscular adaptations for other reasons as well that are going to increase the 1RM. Blood flow restriction training isn't really training for neuromuscular adaptation, so it's not going to be as good for strength as high loads. But from a hypertrophy perspective, when compared to low loads, and then somewhat when compared to high loads, blood flow restriction training does seem to cause pretty robust hypertrophy that's similar to the other methods of training. The last thing that this meta-analysis pointed out is that blood flow restriction training is definitely safe. And I think that if you're going to use kind of an alternative training method, just as it's the first question I ask. So if somebody, same thing I ask if somebody says, hey, are you going to take this supplement or would you recommend this supplement? Even before figuring out if it works or not, I want to say, hey, is this safe? And blood flow restriction training is definitely safe. The way to make sure it stays safe though, is if you can think about when you tie that knee wrap on your upper part of your thigh or the upper part of your arm, you have to think about the tightness in which you tie it. So if you can think about tightness on a scale of one to 10, which you're shooting for is about a seven. So if one is really not tight or no pressure at all, and 10 is maximum pressure, it's tight. And you know, you can't even stand up with the knee wrap tied around the proximal part of your thigh, you know, that's too tight. And I think that could lead to certainly could play a much much greater role in injury than tying the knee wrap, you know, much looser. So, I think you're shooting for around a seven, maybe even a six in terms of the tightness scale or the discomfort scale that you would have. So, if you can do that, you'll be fine. I think maybe it might help if people understand what are you going for? Like what physiologically are you going for, right? Yeah, I think so. So, I think this is, I mean, it's hard to state in exactly how each individual person is feeling, but what I would say is that if you are on a basic sense, if you're sitting down when you tie that knee wrap and you're having trouble standing up and you have to waddle over to the squat rack, it's too tight. If you're seeing discoloration in your leg before you even do an exercise, it's too tight. If you can go ahead and stand up and get over to the rack, no problem. And you feel pretty good. And then after the first or second set, you start to feel like, hey, there's some discomfort there. Then you're on the right track. And that's what you're looking for. Just what you're accomplishing is you're occluding the flowing toward the limbs, but you don't want to go so tight that the blood can't get back. Yes, exactly. So I think that, and just a kind of minor comment on that is I think that you're not really occluding, rather you're restricting. Hence why I would say in 2008, 2009. Oh, because occluding meaning blocking then. Yeah, occluding meaning shutting that off, right? So I think the connotation involved with occlusion or the word occlusion, much more strict or putative, if you will, than blood flow restriction. And that blood flow restriction is just restricting that. So I think the way you phrase that physiologically, what are you doing, is you're just restricting that blood flow. And a 10 tightness or a 9 tightness isn't really restricting it, it's occluding it, it's blocking it. But a 6 or a 7 is a little bit more of a moderate restriction of blood flow. So it's still going to allow you to perform the exercise appropriately. So if you're doing that, again, the main conclusions, this is safe, especially if you use it appropriately there. The increases in strength are going to happen, but not as much as high-load training. Then hypertrophy is pretty similar to low-load and high- high load training. Now, I would say though, that the two limitations of this for hypertrophy are when studies seem to compare blood flow restriction training at 20 to 30% or 1RM to low load training at 20 to 30% of 1RM, they typically equate for volume and for load and for stress, meaning that they typically also equate for reps as well. So if you're doing 20 reps at 20% of 1RM with blood flow restriction training, that's going to be a lot harder than doing 20 reps at 20% of 1RM with no blood flow restriction."

BFR is best used during injury rehabilitation to maintain muscle mass

BFR shines during injury periods when heavy loading is impossible. It allows you to maintain muscle mass with very low loads and minimal joint stress while rehabilitating.

"If you're in a time of injury, I think BFR would be an excellent thing to use. If you can't really load 70, 80, 90% of 1RM and really do a lot of reps with that. But when I stayed around 20, 30% of 1RM, I can do this no problem and I can train."

BFR works through metabolic stress, not mechanical tension like heavy training

Unlike heavy training which relies on mechanical tension and volume, BFR likely works through metabolic stress and cell swelling by trapping metabolites in skeletal muscle.

"So while it does match up for hypertrophy in that sense, I don't think it would match up if there was more stress placed on the low reps in the other group. all the time. do more reps, I think it'd be a better comparison. So while it does match up for hypertrophy in that sense, I don't think it would match up if there was more stress placed on the low reps in the other group. Also, when you look at blood flow restriction training versus high loads, there's really not that much information out there to say, hey, blood flow restriction training for hypertrophy is going to be the same as 70%, 75% of 1RM training. That's pretty close to failure, maybe to an eight or nine RPE. So I do think it could be comparable in some sense. But, you know, if you look at the training status, if you were to get really, really well trained people, and you say, hey, do only blood flow restriction training, versus doing only training, you know, typical hypertrophy training between 65 and 75% or 80% of 1RM, I think it's highly unlikely that BFR would win out or would even be similar. That's not to say, though, that this isn't a strategy that we can use. So when can we use it? Well, this systematic review did show that there was markedly lower joint stress when using BFR. So I think if you're in a time of injury, I think BFR would be an excellent thing to use. If you can't really load heavy and you say, you know what, I can't really load 70, 80, 90% of 1RM and really do a lot of reps with that. But when I stayed around 20, 30% of 1RM, I can do this no problem and I can train. Well, certainly training is going to be better than not training. And if that's not going to lead to more injury and it's much lower joint stress and it's going to keep you in the gym, you're going to be able to, if not grow muscle, at least sustain and not lose muscle if you're not able to train for a few months with higher load. So I think that's a really, really good application to utilize it, to get that in there in times of injury, assuming that the injury is not provoked or not harmed at squatting at that low intensity or benching at that low intensity, doing curls, whatever the exercise might be. Yeah, that absolutely makes sense. And just for those people listening who are wondering, why does this work? What physiologically makes this legitimate? You know, it's a really good question. I don't think we have all of the answers to that. Although I do think we know that it's likely a different mechanism than high load training. You know, high load training is going to be based upon, you know, mechanical tension, which is, you know, really predicated by volume and the amount that you can load, you know, mechanical loading. So you calculate volume sets times reps times load. If you're increasing the number of sets you're doing, you're increasing the reps you're doing, or you're increasing the load, that's going to increase that individual's total volume. And to a point, we know there's a point of diminishing returns for volume, but to a point, you should get better hypertrophic adaptation. With blood flow restriction training, that doesn't really seem to be the case. There's good evidence that more volume isn't really better. So the mechanisms here are probably more along the lines of metabolic stress and cell swelling. And I think those are mechanisms more and more that we know with high load training don't seem to be huge drivers of skeletal muscle hypertrophy. While metabolic stress and cell swelling may play some role in high load training, I do think it's more of the mechanical tension and I do think it's training volume. So I think the mechanisms are more mechanistic here. They could be the pathways that are associated with hypertrophy also leading to protein synthesis response and anabolic protein expression and things like that, those may play some role here with blood flow restriction training. But I think metabolic stress trapping metabolites in skeletal muscle, like we've talked about, if you can restrict the blood flow in, that means you're also restricting the blood flow out. So you're trapping things inside skeletal muscle, which are stimulating some of those anabolic pathways. So I think that plays a much greater role with blood flow restriction training than it does high load training, whereas high load training is more volume. Blood flow restriction training isn't necessarily volume, it's probably more metabolic stress, and those mechanistic factors. But a lot of elucidating a lot of that still remains to be determined. Even though we talked about, you know, this has been a little bit more popular for 10 years, 10 years in the scheme of science is still a relatively short timeframe. So we still have to flesh some of that out, but those are the most likely mechanisms, at least in my opinion, at this point. Yeah, that makes sense. So practically speaking, let's say somebody is dealing with injury now or they're not, but maybe at some point, I mean, hopefully you never do, but if you lift intensely enough for long enough, I guess I wouldn't say the injuries are inevitable, but some aggravations, there are things you're going to have to work around that, that is inevitable, I think for all of us. So let's say practically speaking, if somebody is, let's say before, obviously before an injury, or even just if it's an aggravation of enough severity that they need to work around it, they're doing, let's say a lower body workout is, you know, in mass in, in your whole, in the writeup on it, you have like, okay, cool. So they were, they used to do, or they were doing a squat, a Romanian deadlift, a leg curl and a standing calf raise. And then something happens to where they can't do that, but they would like to continue training lower body. How could they use BFR to do that? Yeah. It's a fantastic question because that's really where we're advocating this here. I'm going to come back to in a moment that this certainly isn't a standalone training method, meaning it's not something that you would do always and all the time. But to answer the question directly, like you said, if somebody was squatting and then all of a sudden they have an injury and for whatever reason, they can't axial load, meaning they can't place the bar on their back, but they want to be able to maintain, you know, as much muscle size as possible. So then when they get back to squatting, they're still in a decent position. A hip thrust is a decent alternative. You could use that instead of squatting. Well, if you do leg curls, you know, you could certainly do BFR with leg curls when you come back. But if that's not the case, you can find something else that stresses the hamstring. Like for example, if you have an RDL, an RDL works on the hamstring, but that also stresses the lower back a little bit, whereas a leg curl isn't going to stress the lower back as much. So maybe when you come back to training, you can do BFR on the leg curl rather than the RDL, and you're still going to be able to stress the hamstrings, but you can do so with a really low load until you can work back up to doing something like RDLs. So it's just a question of if you can still do that exercise, you can replace, let's say a squat with a BFR squat when you come back from injury. If you can't do that exercise, find something else that you can do that stresses the same muscle group and use blood flow restriction on that. And with the goal of not necessarily saying, hey, I'm going to get a ton stronger and a ton bigger, but okay, I'm going to need to do this for about a month until I can get back to my normal training. I want to be able to attenuate or slow the losses and maintain as much as I possibly can until I get back there, find an exercise that stresses that same muscle group, utilize BFR with it. And I think it's pretty safe to say that you're going to be far better off doing that than just simply not training at all. And that's a difficult thing to do. I think sometimes it's hard to find the motivation for that. It's hard to say, you know, I was used to doing this. And now I got to go in, and I got to lift, you know, I'm doing a leg extension, instead of doing the whole stack, I got to put the pin on the second level of the stack and do blood flow restriction, you know, for 2030 reps at a time, it's hard to do. But I think that dedication is going to be what makes the difference for a lot of people in the long run because everybody can train for the long term, but those that are able to be consistent and stick with it, and I think this is one of the things of being consistent is saying, hey, I'm going to adhere to what I need to do. It's easy to go into the gym and it's easy to crush it when you're injury-free and you're feeling great. It's hard to come back from something like this. It's hard to stay focused in doing what you need to do. It's hard to say, I'm not going to aggravate that injury and go bench press heavy today or deadlift heavy today. Rather say, hey, I'm going to do some blood flow restriction on the pec deck today. While that's not as fun, it is what you need to do sometimes. So I think BFR is a really good tool to be able to do that and say, all right, my goal this next month is to maintain as much muscle as I can, not necessarily grow new muscle, but maintain as much muscle as I can. So when I do get back to training normally, I'm in a much better position than if I took the month off. Yep. And, you know, I've gone through that within a few different instances. I had some biceps tendonitis that was annoying and had to, you know, work with a sports doctor and just really had to work around it and not aggravate it. I've had neck tightness. I haven't sustained an acute injury per se, but that's probably because I've at least, I haven't tried to push through pain to the point where I've sustained an acute injury. And also to be fair, I mean, I'm not a competitive weightlifter. I'm not tremendously strong. I have never put up super impressive numbers. I mean, I put numbers that are good enough for me, but you know, so I've had to learn that lesson for people listening. And it was interesting because let's say in my mid to late twenties, it was kind of like what you were saying. It was just always felt good. Nothing really ever even bothered me. I could just go in and, you know, hit everything heavy every week and not really even think about it and recover just fine. And now I'm 33 and I've noticed that, and it's just also the nature of repetitive use. There's something to be said for that, but I'm a little bit more just cognizant of where the boundaries are and what is training smart and what is not. And I can't necessarily do, I can't, I just can't train as intensely, especially on, um, I've noticed it on just the, the big lifts, primarily squat and deadlift a little bit with bench pressing because of the, uh, of the biceps tendonitis. That was, that was annoying. Anyways, I'm, I'm just saying that for people out there, it's, it's, if when you first experience that and having to modify and do things that you know are suboptimal because you are either working around a problem or you see a problem on the horizon, you don't want to have the problem. Yeah, at first, mentally, it can be a little bit demotivating. But you just reframe it. And for me, it's just looking at the long term and looking really what is my goal. Sure. I want to look good, but also I want to feel good. I want to remain injury-free ideally because I want to be doing this for the long haul and I want to be healthy. So that was my experience in terms of shifting from just a pure performance. I just want to lift more weight. I just want to be bigger and stronger to yes, I do. But you know, I have some qualifications now. Yeah, it becomes a secondary goal. I think it's a really good way to look at it from the perspective of, all right, if I'm going to be getting bigger and stronger, that's a relatively short timeframe in my life. You know, if you look at a lifespan where that's going to be the case. So while that is a goal, and if you have progressive overload and abide by the fundamentals, that's going to happen. But it doesn't mean you can't do that in a little bit smarter way. And the other thing I would say is, you know, if you're training, you know, as we talked about a little bit ago is, you know, while injuries, not necessarily, it's not fair to say that's inevitable, I think you put that well, you know, a little aches and pains and aggravations here and there are almost always going to come about for almost everybody. So whenever you have those, or whenever you can feel those coming on, I think a good way to look at this is to say, okay, I got two sets that are left on my program here today. Do I want to do those and then possibly have to take two or three weeks off from the gym because I'm going to aggravate something? Or do I just want to be smart and forego those and realize that missing two sets in the grand scheme of things is completely irrelevant. And then I'm good to go 48 hours from now by being a little smart. You know, I think we've almost all been in a situation where we've decided, you know what, I'm not great. I'm not 100%. But I feel okay. I had to crush these last two sets. And then on that last rep of that last set, man, you feel something snap. And then you just sit down on the bench and just realize, man, I'm out for three weeks, I'm out for four weeks. And then you're just in a bad mood for that next month or so. And then you're trying to rehab it and trying to do all the right things. And hopefully you don't aggravate it again. Whereas if you skip those last two sets and say, I'm going to be smart, you're good to go 48 hours later, that aggravation is never to be heard from again. And you haven't set yourself back. So, and just from a quality of life perspective, I think that's a good idea. I know I've been at fault. I've been at both sides of that. And I've been at fault for pushing it when I knew I shouldn't have sometimes. So I think it's really, really easy to do the wrong thing and say, hey, I'm going to crush it today. I'm going to do this. And it's difficult to say, hey, I'm going to back off. I'm going to miss these last two sets, because you know what, it's just not worth it. And those two sets aren't that big of a deal. So I think it's more difficult to make the smart play. Unfortunately, sometimes we do make the wrong play. And if we do, that's where I think getting back to our conversation, BFR can be a strategy over that next month while you are rehabbing to get back to full strength without losing too much muscle or too much strength. But I just keep that in mind. I would ask yourself, if you are in that situation, that situation arises, would you rather take one day off or two days off, or would you rather take a month off? And if your answer is, I would rather take a day or two off, go ahead and forego those final sets once you feel something aggravated. You might miss out on that training that day, but you'll be a lot happier 48 hours later when you can walk around. Totally agree. So we know we can use it to work around injuries. You don't have to be injured to use it, but not to make it like a primary training modality. Yeah. It's just not a standalone method of training. And I think, um, you know, Mike, this is something we talked about briefly last time I was on and it's, it's that to understand the concepts from research and more and more, that and more, that's something I'm trying to get across. Whereas somebody will look at a research study and say, hey, this was the protocol they did. I'm going to do this exact thing. This is what I do for training now. Well, not necessarily. It's important to understand the concept."