Dr. Patrick: One thing I want to talk to you about, I know we're getting close to the end, and this is something that I know you've talked about in your book before and I've heard people talk about. In fact, I think Joe Rogan was the first guy that told me about this, he talked about it and I was like...you might just see my face on camera, I'm like, "What?" this blood-flow restriction. What is it? You know, are there benefits, drawbacks to it? Like, what...

Dr. Schoenfeld: Yeah. So again, another topic that I've carried out quite a few studies on. So, we talked about light-load training. Blood-flow restriction training uses a cuff. And it's used proximally in the muscle, meaning the upper portion of the muscle that you're looking to train. The caveat is, number one, you can only use it on your arms and legs, you can't train much really your chest or your back or your shoulders because you only can do it proximally. But let's take your biceps, for instance. You would cuff up by the deltoid, the deltoid muscle is your shoulder muscle, you'd place a cuff here, and then you do, let's say, biceps curls, maybe do tricep pressdowns, you know, same thing, the cuff in the same place. With the legs, you would cuff at the groin area, you know, the very upper region of the thigh, and do, let's say, leg extensions or squats.

And generally, you do this with very light loads. They've tried it with heavier loads but it doesn't seem to work as well. Even very light, 20% to 30% 1RM. But when you're using these very light loads, you fatigue much more quickly than if you just did the light load without the cuff. So, let's say, if you're using 30% 1RM, your first set you might get 25 reps, and your second set you're down to 20, and then 15. And usually, the rest intervals are rather short between them.

Good evidence that it promotes similar muscle development to doing traditional resistance training, regardless of the rep range. Strength is similar to light-load training without blood-flow restriction, your strength is not going to be...it's good for hypertrophy but strength is somewhat compromised, which is always going to happen. Heavier loads are going to be better for strength, it's just the way it is. But you still will get...this, again, has been taken...it's not binary, it's not strength, no strength, you just don't get quite as much strength. But you can substantially improve your strength as well, even in well-trained subjects.

Now, the thing is is it better than light-load training? Well, light-load training, I should've mentioned this, and you've done it, you say, it's not fun for a lot of people because you get metabolic acidosis. Again, you have to train hard and you get this burn. And when you're doing it over 30 repetitions, let's say, and it's a 3-second rep, that's a 90-second set. Let's see...70, 80, 90 seconds is a long period of time where you're experiencing that burn, quote unquote. Whereas, if you're doing, let's say, a leg extension or a biceps curl, with blood-flow restriction, you're cutting the time, you're still using the lighter loads, meaning that you're not putting as much joint stress on, but you're cutting the time of that set and, thus, somewhat reducing the discomfort.

Is it necessarily better, from a result standpoint, than lighter-load training? There's been no evidence that we've had, certainly that I've seen on that. But there is some hypotheticals...I can make cases for certain, like, the hypoxia-inducible factor is a substance that is thought to increase the hypertrophic response, intracellular hypertrophic response. So, there are some logical rationales but we don't have any longitudinal evidence showing it's better. And like I said, the limitation to it is the inability to do it, it's only specific to the extremities.

There are some potential...I want to at least bring up the fact, in general, it's shown to be safe but...and people that have blood-pressure issues, I'm not completely convinced there might not be potential issues. And the other thing that I want to point out too is that the research we have is in very controlled environments with researchers that know what they're doing. You get people, they just, like, put a cuff on, their arm starts turning purple where you can really do some damage if you're not doing this properly. So, you have to be cognizant of how to go about doing it if you're going to employ BFR.

Dr. Patrick: I was going to ask you about that, like, "What kind of cuff are we talking about here?" Like, I always think of a tourniquet with blood pressure where it's like...

Dr. Schoenfeld: Well, so, in research settings, there are actually blood-pressure-type cuffs that are used that we can monitor the pressure that's going on. People just use, like, bandana ties and they use a rating scale, like, a discomfort scale of 1 to 10 and saying, "You should be at a 6 or a 7." But a lot of times people don't gauge their, you know, 1 to 10 well and they're saying they're the seven and their arm's turning purple. So, you got to be careful.