 Time for some truth. If you skip leg day, your arms aren't going to grow as much either. All right. Let's talk about this a little bit. I remember the first time I read that somewhere. I thought that was an inch. You know, I don't remember. I think it was like a, I feel like it was a T nation article that I read that where it was like, the article was titled something like, you know, hit a plateau or your arms won't grow, then work on your squat. Yeah. It was like, what? Yeah, I know. Yeah, that blew my mind. So, so here's the science behind it, right? So, and by the way, this has been anecdotally observed in strength building and muscle body building world for a long time. I mean, there were articles written in the seventies that would talk about how adding weight to the squat would get your arms bigger. Or if you gained muscle in your legs, you would notice that you get bigger arms. So people have observed this for a long time. What does this mean? Like, how do we, you know, explain this scientifically? Well, there are studies that show great studies, by the way, where if somebody has, let's say an arm that's broken or an arm that's incapacitated, it will atrophy less if you work the arm that's available. In other words, if I break my left arm, I'm better off training my right arm because it actually prevents muscle loss from happening in my left arm. So what's happening here in the way it's explained is that there isn't a localized acute effect from resistance training. In other words, the muscle you train is going to get most of the muscle building effects, but there's a systemic effect. That happens as well. Do you think this is all attributed to the CNS? Or do you think there's other factors at play? That's a good question. Or is it just the irradiation effect? Which would be the CNS, right? Which would be the CNS. So it's, yeah, I mean, in terms of also being able to stabilize and have that isometric contraction, I'm sure would play a factor in that. Because if I, after I read that, the way that I would explain it to like a client, and I wouldn't do it exactly this way, but I'll refine it with your analogy because I like it so much. And I've brought up your analogy many times on the show since you've brought it up because I think it's one of the best analogies. And I think it works here also, which is your amplifier and speaker analogy. And it's a good example of- I don't use any of your analogy. Come up with random words. You're like, ramp water. Yeah, ramp water. No, it's just so, because this is hard to explain to somebody, right? Yes. It's really like, huh, squatting more. But if you can explain the amp and the speaker analogy, then it does make sense. It's like, oh, even though you're not directly working on the speaker, right? For example, or one of the speakers, you're building the amplifier. And of course, if you build a bigger, better, stronger amplifier, it is going to directly affect all the other muscles or speakers. And so I think that's how I would explain it to a client is like, even though we may not be working on these specific speakers right now, by you squatting, it's squatting so much to building a, I don't know, the more sophisticated CNS, maybe you'd say, or a stronger CNS signal because of its difficulty, right? So and that carryover bleeds into the other muscles. Yeah, the systemic effect is very interesting, right? There's a lot of things that happen. One is what you're talking about. Then there's this like general, you know, increase in muscle protein synthesis. There's these general changes in hormone levels. Myostatin generally gets affected as well, not just acutely or locally, but also kind of systemically. Now I like to explain it from an evolutionary standpoint. I think the body, to become super imbalanced is evolutionarily disadvantageous. So although the body will allow you to build a certain amount of imbalance in order to make you better at whatever you're attempting to do a lot of, too much of an imbalance starts to become a detriment, right? And I think that the systemic muscle building effect is larger with larger muscle groups and smaller with smaller muscle groups. So if I work my biceps, I'll get a localized muscle building effect to the biceps and I'll get some small systemic effect overall. But if it's like my lats or my quads or my glutes or big muscle groups, I mean, if you're working out your legs, you're working out half of your body, you get that localized effect, but then you get this, again, this systemic effect. And so when people skip body parts, they're actually not only are they not developing the body part that they're skipping, which is most of the effect, but they're also impeding the benefits or the muscle building effects that they could get on other body parts. And you talk to anybody who's, and I know I had clients like this where they skip leg day all the time. And then they hired me and I'm like, look, we can't do that. I'm going to train your legs. I'm a trainer. I have integrity. So we got to do it. And then they also gained upper body strength and mass. Yes. And they all comment on it. Why are my upper body is getting stronger? My arms feel bigger. Like what's going on? I'll explain this and say, well, you know, your body doesn't want to be that imbalanced. So skipping leg day, yeah, your legs are small, but your arms are not as big as they could be as well. That's why I always trip on the human body has so many of those mechanisms in place to prevent a lot of those imbalances from happening or at least like kind of bring it back to somewhat of a homeostasis where it's most optimal and like, and this is the same thing with like, you know, when you're in a state of famine, you know, and you're preserving calories, you know, and it has all these like mechanisms in place to make sure that you're utilizing, you know, the energy the most efficient way possible. Totally. If you're training free weights also, there's actually not very, and I actually can't think of any right now that are free weight. I can think of some machines, but if you're training legs, you're almost always incorporating upper body too. Oh, it's holding your stabilizing. There's that factor too. Yeah. I mean, you put 225 pounds or more on your back and your shoulders, your upper back, your abs and core. It has to account for that load. Yeah. So it's getting worked. Of course, it's not like a direct effect like if you were to do shoulder press or do a row or what like that, but it's still, it's still getting worked, you know, so there's got to be some value in that. And right, I can't think of a free weight exercise that you don't use everybody. Now you could do leg extensions, leg curls, leg press where you take the upper body out of it, but most free weight, if not all free weight, lower body exercises still incorporates the upper body. This is one of the reasons why I think generally speaking, people debate this all time, but I think if you were to interview 100 top strength conditioning and muscle building coaches, a majority, maybe not all, but a majority would say that free weights generally build more muscle and strength than machines do. And I think that's one of the reasons why, right? Free weights have, you have that localized effect, but they have more of a systemic effect because so many things are involved. You have to stabilize, you have to stand with the weight typically. If you're working your lower body, you're still holding the weight with your upper body and all that stuff. Here's another example. If you're watching this right now, if you have something that can measure your grip strength, go ahead and try squeezing as hard as you can while maintaining total relaxation in the rest of your body. Don't grit your teeth, don't squeeze the other hand. Everything totally relaxed and just activate your grip and then try it again, even though you might even be a little fatigued from your first attempt and then squeeze your entire body and see how much stronger you are. You'll notice a 10%, 15% increase in strength. By the way, you'll notice how hard it is to activate maximally while relaxing everything. It's not a natural thing. Your body wants to turn on its CNS to generate muscle force. Oh, I don't even think you need something to measure. Someone right now could literally just relax your mouth, relax your body, squeeze your hand and then allow yourself to grit your teeth and squeeze the other hand and you can instantly feel your palm just get tighter. Oh, totally. But the studies on right to left, it's so interesting. You'll have like one leg totally incapacitated, so of course it's going to atrophy. They'll train the other leg and they'll compare this to groups where they don't train the other leg and they just leave them both. You lose less muscle in the leg that's not trained. It's such an interesting, but again, evolutionarily speaking, it makes perfect sense. I mean, our bodies evolved always trying to make us help us survive and so all of it makes sense from that standpoint. Like you mentioned, famine and the metabolism adapting and all that. I mean, it makes absolute perfect sense, but it is interesting. And a lot of people don't, by the way, this is true for women too. You want to build a bigger butt and you're not working out your upper body. You're not going to build the butt that you can because you're avoiding training the rest of your body. There's a lot of my female clients that would avoid a lot of upper body exercises, especially chest press or something like that. Yes, it all works together. So this is all very, very important. Hey, if you enjoyed that clip, you can find the full episode here or you can find other clips over here. And be sure to subscribe.