Science of Muscle Growth, Increasing Strength & Muscular Recovery | Huberman Lab Podcast #22
- Welcome to the Huberman Lab Podcast where we discuss science and science-based tools for everyday life. [upbeat music] I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. This podcast is separate from my teaching and research roles at Stanford. It is however, part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public.
In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is InsideTracker. InsideTracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and reach your health goals. I've long been a fan of getting blood work done for the simple reason that many of the things that impact our immediate and long-term health can only be analyzed from a quality blood test. And now with the advent of modern DNA tests, we can also get insight into things like metabolic factors that tell us whether or not we metabolize caffeine well or certain proteins well, what our fat metabolism genes are like. Things of that sort can only be analyzed from quality blood and DNA tests.
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Today's podcast is also brought to us by Belcampo Meat Company. Belcampo is a regenerative farm in Northern California that raises organic grass fed and finished certified humane meats. While I don't eat a lot of meat, when I do, I insist that that meat be a very high quality. How the animals were cared for is extremely important to me and the life that the animal had and what it consumed is very important to me. So the way that I eat I've discussed on this podcast before, but very briefly, I basically fast until about noon then I eat a piece of beef or chicken with lunch and a salad. So that's basically my lunch.
That's what optimizes my levels of alertness for work throughout the day. Then in the evening, I shift over to eating primarily carbohydrates. That's what allows me to sleep very well. So I'm not eating huge volumes of meat, but am eating meat every day. Conventionally raised animals are confined to feed lots and need to die of inflammatory grains, which is bad for them and it's bad for us when we eat their meat. Belcampo's animals graze on open pastures and seasonal grasses resulting in meat that is higher in nutrients and healthy fats.
And I've talked before about the importance of omega-3 fatty acids for both brain and body health, and Belcampo meats are high in omega-3 fatty acids. The way Belcampo raises its animals isn't just better for your health, it also has a positive impact on the environment. It's what's called climate positive and carbon negative, which means good for the planet and good for us. My favorite meats from Belcampo are the ribeye and the flank steaks. That's typically what I eat. I think I probably eat about three or four of those across the week and then I'll eat chicken on some other days.
They're really delicious and as I mentioned, they're very good for us. You can order Belcampo's sustainably raised meats to be delivered straight to your door using my code Huberman at belcampo.com/huberman. If you do that, you'll get 20% off first time order. That's belcampo.com/huberman for 20% off your first order. Today's episode is also brought to us by Headspace.
Headspace is a meditation app backed by 25 published studies and has over 600,000 five star reviews. So I've been meditating on and off since I was about 15, 16 years old, mostly off at first. What I found is that I'll sometimes start a meditation practice but it's very hard to stay with. And then a few years ago I discovered Headspace and I started meditating more regularly. In fact, very recently because I've had an exorbitant amount of work on my plate and I've been getting less sleep than I would like in order to complete that work, I've brought back a regular meditation practice twice a day not just my usual once a day.
Headspace makes it really easy. They have so many meditations on there and they guide you into the meditation and out of the meditation in a way that just makes it very simple and makes maintaining the practice really straightforward. Right now if you want to try Headspace, you can go to headspace.com/specialoffer. And if you do that, you'll get a free one month trial, so that's totally free, with their full library of meditations for every situation.
So there's no meditations that you can't get access to with this offer, you can get access to everything they've got. You just go to headspace.com/specialoffer, you get a free one month trial and hopefully you'll decide to stay with it. I've found that staying with meditation has been immensely beneficial for all aspects of my life. Today's episode of the Huberman Lab Podcast is our fourth and final episode in this month, which is all about skills and athletic performance.
Now, in a previous episode, we talked about science-based in particular neuroscience-based tools for accelerating fat loss. Previous to that, we talked about ways to improve skill learning, motor movements, which also included things like music and piano playing not just athletic performance. And we've also been exploring other aspects of physical performance throughout the entire month.
Today I want to talk about something that is vitally important for not just athletic performance, but for your entire life and indeed for your longevity and that's muscle. Now, many of you when you hear the word muscle think muscle growth and building big muscles. And while we will touch on muscle hypertrophy, muscle growth today and science-based protocols to enhance hypertrophy, we will mainly be talking about muscle as it relates to the nervous system. And I can't emphasize this enough, the whole reason why you have a brain is so that you can move.
And one of the things that's exquisite and fantastic about the human brain is that it can direct all sorts of different kinds of movement, different speeds of movement, movement of different durations. We can train our musculature to lift heavier and heavier objects or we can train our musculature to take us further and further, so-called endurance. We can also build smoothness of movement, excuse me, smoothness of movement as well as speed of movement, suppleness of movement. All of that is governed by the relationship between the nervous system neurons and their connections to muscle.
So when you hear the science of muscle and muscle hypertrophy, you might think, "Oh, well I'm not interested in building muscle." But muscle does many critical things. It's important for movement, it's important for metabolism. The more muscle you have and not just muscle size but the quality of muscle, that's a real thing, the higher your metabolism is and indeed the healthier you are. It turns out that jumping ability and ability to stand up quickly and to get up off the floor quickly is one of the most predictive markers of aging, in biological aging and no surprise, that is governed by the brain to muscle connection.
In addition, muscle and musculature is vital for posture and we don't talk about posture enough. We all have been told we need to sit up straight or stand up straight, but posture is vitally important for how the rest of our body works. It's vital to how we breathe, it's actually even vital to how alert or sleepy we are. So we're going to talk about the musculature for posture. We also are going to talk about muscle as it relates to aesthetic things.
Now, these are all linked, muscle for metabolism, movement, posture and aesthetics of course are linked, right? As our posture changes, our aesthetic changes. As our posture and aesthetic changes, how we move changes. And as we improve muscle quality, whether or not that's increasing muscle size or not, that changes the way that our entire system, not just our nervous system and our muscular system but our immune system and the other organs of the body work. So today as always, we're going to talk a little bit of mechanism. I'm going to explain how neurons control muscle and then we're going to look at muscle metabolism, how muscle uses energy.
I promise to make all of this very simple. I'm actually going to keep it very brief, probably about 10 minutes total. And by the end of that 10 minutes, you will understand a lot about the neuromuscular connection, how your brain and nervous system control your muscle and how those muscles work. Then we are going to talk about how muscles use energy and can change how they use energy for sake of getting stronger.
If you like, for also increasing the size, so-called hypertrophy of muscle and for improving endurance, as well as for improving posture and how you move generally. We will touch on some nutritional themes and how that relates to muscle in particular a specific amino acid that if it's available in your bloodstream frequently enough and at sufficient levels can help you build and improve the quality of muscle. And we'll talk about specific exercise regimes as well as of course, supplementation and things that can enhance neuromuscular performance overall. We are also going to talk about recovery.
Recovery, as everybody knows, is when things improve. That's when neurons get better at controlling muscle, that's when muscle grows, that's when muscle gets more flexible. None of that actually happens during training, it happens after training and there is a lot of confusion about how to optimize recovery and how to measure whether or not you are recovered and ready to come back in for another neuromuscular training session. So we'll talk about that as well.
Today is going to have a lot of protocols and you're going to come away with a lot of understanding about how you move, how you work and these incredible organs that we call the nervous system and the musculature, the so-called neuromuscular system. Before we dive into today's topic, I want to just take about three minutes and cover some essential summary of the previous episode. In the previous episode, we talked about fat loss, talked about shiver induced fat loss. We talked about neat non-exercise activity thermogenesis for increasing caloric burn and fat oxidation. And we talked about how to use cold, specifically to enhance fat loss.
I described a protocol involving getting into cold of some sort, whether or not it's ice bath, cold shower, some form of cold, could even be a river or an ocean if you have access to that and inducing shiver and then getting out not crossing your arms or huddling, but allowing that cold to evaporate off you and continuing to shiver and then getting back into the colder environment of water or stream or shower, et cetera. All of that is described in a beautifully illustrated protocol that I didn't illustrate. That's why it's beautifully illustrated at thecoldplunge.com. They've made that protocol for you and they've made it available free of charge for you. So there's no obligation there of any kind financially. You can go to the coldplunge.com.
There's a little tab that says protocols and you can download that protocol. Someone there, I don't know who exactly illustrated it and you can come away with a PDF of what I described in the previous episode. So I just want to make sure that you are aware of that resource.
The other announcement I'd like to make is that many of you have asked how you can help support the podcast and there's a very straightforward zero cost way to do that. And that's to subscribe to our YouTube channel. So if you go to YouTube, if you're not already there watching this now, hit the subscribe button, that helps us tremendously to get the word out more broadly about the podcast and we thank you for your support. Most people when they hear the word muscle, they just think about strength. But of course, muscles are involved in everything that we do. They are involved in speaking, they're involved in sitting and standing up, they're involved in lifting objects, including ourselves.
They are absolutely essential for maintaining how we breathe. They're absolutely essential for ambulation, for moving and for skills of any kind. So when we think about muscle, we don't just want to think about muscle, the meat that is muscle, but what controls that muscle. And no surprise what controls muscle is the nervous system. The nervous system does that through three main nodes of control, areas of control.
And I've talked about these before on a previous podcast. So I will keep this very brief. Basically we have upper motor neurons in our motor cortex.
So those are in our skull and those are involved in deliberate movement. So if I decide that I'm going to pick my pen up and put it down, which is what I'm doing right now, my upper motor neurons were involved in generating that movement. Those upper motor neurons send signals down to my spinal cord where there are two categories of neurons, one are the lower motor neurons and those lower motor neurons send little wires that we call axons out to our muscles and cause those muscles to contract. They do that by dumping chemicals onto the muscle. In fact, the chemical is acetylcholine.
I've talked before about acetylcholine in the brain which is vitally important for focus and actually can gait neuroplasticity, the brain's ability to change in response to experience. But in the neuromuscular system, acetylcholine released from motor neurons is the way, the only way that muscles can contract. Now there's another category of neurons in the spinal cord called Central Pattern Generators or CPGs and those are involved in rhythmic movements.
Anytime we're walking or doing something where we don't have to think about it to do it deliberately, it's just happening reflexively, that Central Pattern Generators and motor neurons. Anytime we're doing something deliberately, that top-down control as we call it from the upper motor neurons comes in and takes control of that system. So it's really simple, you've only got three ingredients.
You've got the upper motor neurons, the lower motor neurons and for rhythmic movements that are reflexive, you've also got the Central Pattern Generators. So it's a terrifically simple system at that level. But what we're going to focus on today is how that system can control muscle in ways that make that system better. Now, when I say better, I want to be very specific. If your goal is to build larger muscles, there's a way to use your nervous system to trigger hypertrophy, to increase the size of those muscles. And it is indeed controlled by the nervous system.
So you can forget the idea that the muscles have memory or that muscles grow in response to something that's just happening within the muscle, it's the nerve to muscle connection that actually creates hypertrophy. I'll talk exactly about how to optimize that process. In addition, if you want to improve endurance or improve flexibility or suppleness or explosiveness, that is all accomplished by the way that the nervous system engages muscles specifically. And so what that means is we have to ask ourselves are we going to take control of the upper motor neurons, the Central Pattern Generators or the lower motor neurons or all three in order to get to some end point of how the nervous system controls muscle. So neurophysiology 101, I'll give you one piece of history because it's important to know.
Sherrington who won the Nobel prize called movement, the final common path. Why did he say that? Well, the whole reason for having a nervous system, the whole reason for having a brain is so that we can control our movements in very dedicated ways. That is one of the reasons, perhaps the predominant reason why the human brain is so large. You might think, "Oh, it's so large for thinking "and for creativity." Ah, no, when you look at the amount of real estate in the brain that's devoted to different aspects of life, it's mainly vision, our ability to see and movement, our ability to engage in lots of different kinds of movements, slow movements, fast movements, explosive, et cetera. Other animals don't have that ability because they don't have the mental real estate, they don't have the neural real estate in their brain.
They have neuromuscular junctions, they have Central Pattern Generators. What they don't have are these incredible upper motor neurons that can direct activity of the muscles in very specific ways. So we can all feel blessed that we have this system. And today I'm going to teach you how to use that system toward particular end points. So if we decide that we are going to direct our muscles in some particular movement of any kind, whether or not it's a weightlifting exercise or whether it's a yoga movement or simply picking up and putting down a pen, we are engaging flexors and extensors and our body is covered with flexors and extensors all over. So for instance, our bicep is a flexor and our tricep is an extensor.
Those are what are called antagonistic muscles. They move the limbs in opposite directions. So if you bring your wrist closer to your shoulder, that's flection using your bicep. If you move your wrist further away from your shoulder, that's extension, using your tricep. And without getting into a lot of detail, the way that the nerves and brain are wired up to muscle make it such that when a flexor is activated, when the nerve dumps chemical acetylcholine onto the muscle to activate the biceps, the triceps is inhibited.
It's prevented from engaging. There are ways to bypass this, but that's the typical mode of action. The converse is also true, when our tricep is activated, when we move our wrist away from our shoulder, our bicep is inhibited. And we have flexors like our abdominal muscles and we have extensors in our lower back. Many of you probably know this, but some of you probably don't that your spine has flexors to move basically your chin toward your waist.
And it has, those are your abdominal muscles among others. And you have extensors that move your chin, basically back like looking up toward the ceiling, and those are your extensors. You have other muscles that are stabilizing muscles and things of that sort, but those movements of flection and extension, and the fact that they are what we call reciprocally innovated or mutual inhibition, you hear different language around this, is characteristic of most of our limb movements. So hamstring and quadriceps.
The hamstring brings the ankle closer back towards the glutes. Basically it's lifting your heel up, which is almost always done toward the back. Whereas your quadriceps is the extensor, opposite to the hamstrings.
So you get the idea. So there's flexors and extensors and it's the neurons that control those flexors and extensors that allow us to move in particular ways. So now you have heard a neuromuscular physiology in its simplest form, but I do want this to be accessible. I want to get just briefly, just briefly into some of the underlying metabolism of how muscles use and create energy, because in doing that, we will be in a great position to understand all the tools that follow about how to optimize the neuromuscular system for your particular goals. So in the previous episode about fat loss, we talked about lipolysis, the breakdown of fat into fatty acids so it can be used as fuel and it ended in a step where we got ATP, which is the bottleneck and final common path for all energy producing functions in the body.
There are other ways, but basically ATP is the key element there. Now with muscles, they don't function on fats normally, what they are going to function on their ability to move and their ability to do things and allow us to move in any way that we want to is based on a process of glycolysis, the breakdown of things like glycogen and glucose into energy. And it's a very simple process. You don't have to know any chemistry. So if I say the words carbon or hydrogen or something like that, don't freak out, you don't have to understand any chemistry. But basically what happens is you've got this available sugar resource that stored in muscle.
And that's glucose. And that glucose has six carbons and six waters basically. That can be broken down into two sets of three carbons.
All right, so basically you take glucose and you break it into these two little batches of carbons that we call pyruvates. So six divided by two is three, so you get three pyruvates. And that generates a little bit of ATP of energy, but just a little bit. Now, if there's oxygen available, okay, if there's sufficient oxygen there, what can happen is that pyruvate can be brought to the mitochondria and through a whole set of things that you probably don't want to hear about right now like the electron transport chain and citric acid cycle. What happens is it's broken down and you get 28 to 30 ATP, which is a lot of ATP.
So the only things you need to know, the only things you need to know about this process is that glucose and glycogen are broken down into pyruvate. You get a little bit of energy from that. And when I say energy, I mean the ability to move. It's fuel, literally just gets burned up. But if there's oxygen available and that's key, then within the mitochondria, you can create 28 to 30 ATP which is a lot of ATP.
Now, what does this mean? This means that movement of muscle is metabolically expensive and indeed compared to other tissues compared to fat, compared to bone, compared to almost all other tissues except brain tissue, muscle is the most metabolically demanding, which is why people who have more muscle relative to adipose tissue, to fat, they can eat more and they're more of a furnace, they just kind of burn that up. So even if you didn't understand anything that I just said, what you probably did hear, and that I hope you heard is that if you have oxygen around, you can create energy from this fuel source that we call glycogen and glucose. But what if there isn't oxygen around and what is that like? Well, you've experienced that.
I'm not talking about oxygen in the environment, I'm talking about oxygen in the muscle. So if you've ever carried a box while moving or you're carrying heavy groceries to the car or you're exercising particularly hard and you felt the burn, well, that burning which most people think is lactic acid is actually a process by which pyruvate, which as I said before, normally could be converted into ATP if there's oxygen. Well, if there's not enough oxygen 'cause that muscle is working too hard or too long, what ends up happening is that a hydrogen molecule comes in there and you get something called lactate. So believe it or not, humans don't make lactic acid, that's in other species, we make lactate.
And we think, and we hear that lactate is bad. We need to buffer the burn or avoid the burn, that lactic acid and lactate are what prevent us for performing as well as we ought to be able to, or for going as far as we possibly could in an endurance event. Guess what, that's not true at all.
Lactate has three functions, all of which are really interesting and really important. First of all, it's a buffer against acidity. You don't want muscle to get too acidic because it can't function. You don't want any body tissue to get too acidic. So that burn that you feel is acidity in that environment, that and lactate what most people call lactic acid, but again, we don't make lactic acid.
Lactate is there to buffer that, to reduce the amount of burn. So most people have this exactly backwards. So when you feel that burn, that is not lactic acid, that is lactate that's present to suppress the burn, to suppress acidity. It's also a fuel. When you feel that burn, lactate is shuttled to those areas of the muscle and there's an actual fuel burning process where in the absence of oxygen, you can continue to generate muscular contractions.
Now, this is informative 'cause it also tells us that that burning, that acidity that we feel can inhibit the way that our muscles work, but that lactate comes in and allows our muscles to continue to function. So we'll talk a little bit more about what this whole lactate thing and the burn means, but it's a really important process. And it's amazing to me that most people understand it in exactly the incorrect way. They think a lactic acid is bad and the burn is bad. No, it reveals a number of really important things are going on with this vital molecule lactate, which can reduce acidity, reduce the burn as well as act as a fuel.
Now here's where it gets really, really cool. And if you don't have enough of an incentive to exercise based on all the information out there about how it'll make you live longer and make your heart better, et cetera, here's a reason that regardless of what kind of exercise you do, if it's weight training or running or cycling or swimming, that every once in a while, about 10% of the time you should exercise to the point of intensity where you start to feel that so-called burn. The reason for that is that lactate shows up to the site of the burn, so to speak, and it acts as a hormonal signal for other organs of the body in a very positive way.
As you may recall from a very early episode of the Huberman Lab Podcast, I talked about what a hormone is and how it works. We have lots of different kinds of hormones, but hormones are chemicals that are released in one location in the body and travel, have effects on lots of other organs of the body. So when I say that lactate acts as a hormonal signal, what I mean is that it's in a position to influence tissues that are outside of the muscle. And basically it can send signals to the heart, to the liver, and to the brain, and it can have effects on the heart, the liver, and the brain that are very positive. So just to zoom out for a second, I promise we won't get any more technical than this.
We will get into tools and protocols that are really straightforward. But what I'm telling you is that if you feel a burn from a particular exercise or movement, that burn is going to be buffered by this molecule we call lactate. Lactate will then provide additional fuel for additional work. So this is a good incentive provided you can do it safely to quote unquote, work through the burn.
That burn acts as a beacon to the lactate, which comes in and allows you to do more work. It's not a signal to stop necessarily. I mean, stop if you're doing something unsafe, but it's a signal that lactate should come in and allow you to continue to do work. And it can act as a hormonal signal.
Lactate can then travel to the heart and to the liver and to the brain and can enhance their function in positive ways, not just in those moments, but in the period of time that follows. So many people are curious about how they can exercise to make their brain better. That's one of the most common questions I get. What I'm telling you is that provided you can do it safely by engaging the so-called burn, which is at a different threshold for everybody. Your hill run will be different than my hill run to generate the burn. But provided you can do that for about 10% of your workouts or of an individual workout or activity of any kind, you are generating the activity of this lactate based hormonal signal that can improve the function of neurons and it does that if you want to know for the aficionados, by improving the function of another cell type called the astrocytes which are a glial cell type.
Which are very involved in clearance of debris from the brain, they're involved in the formation of synapses, connections between neurons in the brain. So put simply, if you're an exerciser, if you're doing movement of any kind and you're interested in allocating some of that movement toward enhancing brain, heart and liver health, there is a nice set of scientific data that points to the fact that getting lactate shuttled to the muscles by engaging this burning sensation is advantageous for the health of those other tissues. I want to avoid too much detail, but there is an interesting twist in this that you can leverage as well.
So, as I mentioned, that burn is from lack of oxygen being present, something called the covacycle. Actually, let me, I don't want to give any more nomenclature. So as I mentioned, that burn is present from lack of oxygen being present, and then the hydrogen comes in and you get this lactate.
But this process of lactate acting as a buffer of fuel and a positive hormonal signal for other tissues occurs only if there's oxygen. So if you feel the burn, you definitely want to focus on your breathing at that point. That will be the time to take deep inhales and try and bring more oxygen into your system. It's definitely not a time to hold your breath. And if ever you've run to the point of feeling the burn and then you were exercised in any way on the treadmill or on the bike or whatever and felt that burn and then you held your breath, it feels much more intense.
By breathing, you bring lactate to the site and you are able to allow lactate to act more as a buffer, a fuel and a hormonal signal. And the reason I brought this up today is because as I mentioned so many people are interested in using exercise, not just for sake of improving physical health and wellbeing and performance, but also for enhancing their brain. And there are a lot of data out there speaking to the findings that exercise of various kinds can increase neurogenesis, the creation of new neurons. Well, the unfortunate news is that while that's true in mice, there is very little evidence for enhanced neurogenesis from exercise or otherwise in humans. There's a little bit and there are a few sites within the brain, such as the dentate gyrus of the hippocampus, which may be involved in the formation of new memories. To be clear, the dentate gyrus is definitely involved in the formation of new memories, whether or not the new neurons that are added there in humans are involved in new memories is, the evidence for that is weak at best, frankly, whereas in animals the data are quite strong.
But most of the data points to the fact that hormonal signals, things that are transported in the blood during exercise are what are beneficial for the brain, excuse me. And that those signals are not causing the increase in the number of neurons in the dentate gyrus or otherwise, that it's more about the health of the connections between the neurons, growth factors of various kinds things like IGF1, there's a long list of these things. So if you've heard that exercise increases the number of neurons in your brain, well, that's not true. And that probably is a good thing, frankly because we always hear more neurons, more neurons as if it's a good thing, but the brain doesn't do so well with bringing in entirely new elements. It has a hard time negotiating that and making use of those new elements.
We know about this from things like the cochlear implant where deaf people are given a device where they suddenly can hear. Some people really like that, deaf people really like that and can benefit from it. Other deaf people find that it's very intrusive, that is hard to take an existing neural circuit in the brain and incorporate a lot of new information into it. So new neurons, as great as that sounds more neurons, more neurons, it actually might not be the best way for the nervous system to change and modify itself and to promote its own longevity. So when I tell you, not such great evidence for a new neurons past puberty, that's what the data really show in humans. And I sort of knocked back the data on exercise and neurogenesis, don't let that depress you.
If you have dementia in your family, don't translate that into necessarily that you will develop dementia. Understand the exercise is still beneficial for the brain and other aspects of the nervous system, but that it's going to be doing it through these hormonal signals. Things like IGF1, things like this lactate pathway when you experience the burn from exercise.
And again, you don't want to try and get this feeling of a burn throughout the entire episode of exercise, there'll be far too intense and would inhibit your recovery. I don't think you'd be good for performance either. It's only about 10% of your total effort in any one exercise about that's going to give you this positive effect.
So now you know how to devote a small portion of your exercise, 10% in order for muscle and lactate to benefit other tissues, namely your heart, your liver, and your brain. And now I'd like to shift our attention to how to use specific aspects of muscular contraction to improve muscle hypertrophy, muscle growth, as well as improving muscle strength. There are a lot of reasons to want to get stronger. And I should just mention that it's not always the case that getting stronger involves muscles getting bigger. There are ways for muscles to get stronger without getting bigger. However, increasing the size of a muscle almost inevitably increases the strength of that muscle, at least to some degree.
Reasons why most everyone should want to get their muscles stronger is that muscles are generally getting progressively weaker across the lifespan. So when I say getting stronger, it's not necessarily about being able to move increasing mounts of weight in the gym, although if that's your goal what I'm about to discuss will be relevant to that. But rather to offset some of the normal decline in strength and posture and the ability to generate a large range of movement safely that occurs as we age. As I mentioned at the beginning of the episode, we just tend to lose function in this neuromuscular system as we get older, and doing things to offset that has been shown again and again to be beneficial for the neuromuscular system, for protection of injury, for enhancing the strength of bones and bone density. So there are a lot of reasons to use resistance exercise that extend far beyond just the desire to increase muscle size, because I know many of you are interested in increasing muscle size, but many of you are not.
So there's an important principle of muscle physiology called the Henneman's size principle. And the Henneman's size principle essentially says that we recruit what are called motor units. Motor units are just the connections between nerve and muscle in a pattern that staircases from low threshold to high threshold. What this means is when you pick up something that is light, you're going to use the minimum amount of nerve to muscle energy in order to move that thing.
Likewise, when you pick up an object that's heavy, you're going to use the minimum amount of nerve to muscle connectivity and energy in order to move that object. So it's basically a conservation of energy principle. Now, if you continue to exert effort of movement, what will happen is you will tend to recruit more and more motor units with time. And that process of recruiting more neurons, more lower motor neurons. If you recall from the beginning of the episode, these lower motor neurons are in our spinal cord and they actually dump a chemical acetylcholine on muscle, cause the muscles to contract.
As you recruit more and more of these motor units, these connections between these lower motor neurons and muscle, that's when you start to get changes in the muscle, that's when you open the gate for the potential for the muscles to get stronger and to get larger, if that's what your goal is. And so the way this process works has been badly misunderstood in the kind of online literature of weight training and bodybuilding and even in sports physiology. The Henneman's size principle is kind of a foundational principle within muscle physiology but many people have come to interpret it by saying that the way to recruit high threshold motor units the ones that are hard to get to is to just use heavy weights.
And that's actually not the case as we'll talk about, the research supports that weights in a very large range of sort of a percentage of your maximum, anywhere from 30 to 80%. So weights that are not very light but are moderately light to heavy can cause changes in the connections between nerve and muscle that lead to muscle strength and muscle hypertrophy. Put differently, heavy weights can help build muscle and strength, but they are not required. What one has to do is adhere to a certain number of parameters, just a couple of key variables that I'll spell out for you.
And if you do that, you can greatly increase muscle hypertrophy, muscle size and or muscle strength if that's what you want to do. And you don't necessarily have to use heavy weights in order to do that. Now I'm sure the powerlifters and the people that like to move heavy weights around will say, "No, if you want to get strong, you absolutely "have to lift heavy weights." And that might be true if you want to get very strong, but for most people who are interested in supporting their muscular such that they offset any age-related decline in strength or in increasing hypertrophy and strength to some degree, there really isn't a need to lie about the Henneman's size principle which many people out there are doing and claiming that you absolutely need to use the heaviest weights possible in order to build strength and muscle. So I'm going to explain how all of this works in simple terms.
So first of all, let's just talk about what hypertrophy is and what strength changes in the muscle are. We can make this very simple as well. If this were a muscle physiology class, we would talk all about myofibrils and sarcomeres and all that stuff, we're not going to do that, that's not the purpose of today's conversation. If you're interested in that, as well as a lot of the other information that I'm going to discuss in more detail, I highly encourage you to check out the YouTube channel from and the writings of Dr. Andy Galpin. He's a PhD and a full professor in exercise physiology. He's extremely knowledgeable in this entire area of science-based tools for hypertrophy, how strength and hypertrophy really work.
His lab does everything from biopsy on muscles working with athletes and typical folks as well. A lot of the information that you're going to hear from me in the next 15 minutes or so comes from an extensive exploration of the work that he and his colleagues have done as well as folks like Brad Schoenfeld, another academic who's suburb in this whole space of muscle physiology and from a lengthy conversation that I had with Andy, Dr. Galpin prior to this episode. So if we want to think about also hypertrophy, we have to ask what is changing when muscles get larger or stronger? And there are really just three ways that muscles can be stimulated to change.
So let's review those three ways and talk about what happens inside the muscle. So there are three major stimuli for changing the way that muscle works and making muscles stronger, larger, or better in some way. And those are stress, tension and damage.
Those three things don't necessarily all have to be present but stress of some kind has to exist. Something has to be different in the way that the nerve communicates with the muscle and the way that the muscle contracts or performs that makes the muscle need to change. So this is very reminiscent of neuroplasticity in the brain.
Something needs to happen, certain chemicals need to be present, certain processes need to happen or else a tissue simply won't change itself. But if those processes and events do happen, then the tissue has essentially no option except, but to change. So muscles move, as I mentioned because nerves dump chemical onto the muscles, but they move because they have these things called myosin and actin filaments, and if you want to read up on this, you can look on the internet.
You can put the sliding filament theory of muscle contraction if you really want to go deep down that rabbit hole. It's interesting, you can learn about this in a muscle physiology class. But basically along the length of the muscle, you have what's called myosin. And just think of myosin as it's kind of like a wire. It's like a bunch of beads and wires that extend across the muscle.
I think that's the simplest way to describe it. And the myosin is surrounded by these little beads called actin. The way muscles get bigger is that basically the myosin gets thicker. It's a protein and it gets thicker.
So put this in your mind, if you're listening to this or even if you're watching it on YouTube. The way to think about this whole actin myosin thing and muscles getting bigger is imagine that you're holding a bouquet of balloons, a bunch of balloons by their strings except you're not holding the strings all at their bottom. So the bouquet isn't nicely arranged. It's not like some balloons that are all up at the top and you're holding the strings down at the bottom. Imagine that one of the balloons is very close to your hand, another one is a little bit higher up. And so this bouquet is very disorganized.
In other words, the string extending out of your hand the strings rather extending out of your hand are all different lengths. And so the balloons are all over the place. That's essentially what myosin looks like in the muscle.
And those strings are what we call the filaments. And then the myosin head is the balloon. When you stress a muscle properly or you give it sufficient tension or you damage the muscle just enough, there's an adaptive response that takes place where protein is synthesized and it's a very specific protein, it's myosin. The myosin gets thicker.
In other words, the balloons get bigger. So the way to think about muscle growth and the way to think about muscles getting stronger is that those balloons get bigger and the muscle gets thicker. Now the question then should be as always, how does that happen? I mean, the muscle doesn't really know anything about what's happening in the outside world. The way it happens is the nerve, the neuron has to tell the muscle to get stronger. And it does that through what we call a signaling cascade.
It talks to the muscle in terms of chemicals, it doesn't whisper to it or shout or "Hey, get bigger." What it does, it release a certain chemicals that within the muscle there are certain chemicals released rather that make those balloons as I'm referring to, the myosin get thicker. So let's talk about the stimulus for doing that. And if already in your mind, you're imagining "Oh, my goodness, these balloons of muscle "are going to get thick, thick, thick, thick, thick "and that's just going to spiral out of control." Don't worry about that.
People invest a ton of time and energy into trying to make their muscles larger. It's actually much harder for people to do than you might think. But I do want to give one exception because it illustrates an important principle of where we're headed next.
Everybody has imbalances in how muscles can grow, how well muscles can grow, or how poorly or how challenging it is for their muscles to grow. Now, many people who are afraid of getting too bulky for instance, are afraid of lifting weights. But I think the research shows now that every one of pretty much every age should be doing some sort of resistance exercise, even if that's body weight exercises in order to offset this age-related decline in muscle contractile ability, muscle strength, et cetera, improve bone density. There's nothing good about getting frail and weak over time.
And people who invest the effort into doing resistance exercise of some kind, whether or not it's with bands or with weights or with body weight really benefit tremendously at a whole body level, at a systemic level as well as in terms of muscle strength. There is a good predictor of how well or how efficient you will be in building the strength and or if you like the size of a given muscle. And it has everything to do with those upper motor neurons that are involved in deliberate control of muscle. You can actually do this test right now. You can just kind of march across your body mentally and see whether or not you can independently contract any or all of your muscles.
So for instance, if you are sitting in a chair or you're standing, see whether or not you can contract your calf muscle just using those upper motor neurons, sending a signal down and deliberately isolating the calf muscle. If you can contract the calf muscle hard to the point where that muscle almost feels like it's starting to cramp, like it hurts just a little bit. It's not going to be extremely painful nor is it going to have no sensation whatsoever. Chances are you have very good upper motor neuron to calf control.
And chances are, if you can isolate that, what they call the brain or mind muscle connection and you can contract the muscle to the point where it cramps a little bit, that you hold a decent to high potential to change the strength and the size of that muscle if you train it properly. Now, if you have a hard time doing that, chances are you won't be able to do that. If for instance, you focus on your back muscle, like we all have these muscles called the lat, the latissimus dorsi muscles, which basically are involved in chin-ups and things like that, but their function from a more of a kinesiology standpoint is to move the elbow back behind the body. So it's not about flexing your bicep, it's about moving your elbow back behind your body. If you can do that mentally or you can do that physical movement of moving your elbow back behind your body, and you can contract that muscle hard, chances are that you have the capacity to enhance this strength and or size of that particular muscle because you have the neural control of that muscle. This is a key feature of the neuromuscular system to appreciate as we begin to talk more about specific protocols because everything about muscle hypertrophy, about stimulating muscle growth is about generating isolated contractions, about challenging specific muscles in a very unnatural way.
Whereas with strength, it's about using musculature as a system moving weights, moving resistance, moving the body. The specific goal of hypertrophy is to isolate specific nerve to muscle pathways so that you stimulate the chemical and signaling transduction events in muscle so that those muscles respond by getting larger. So there's a critical distinction in terms of getting stronger versus trying to get muscles to be larger hypertrophy per se.
And it has to do with how much you isolate those muscles. Muscle isolation is not a natural phenomenon. It's not something that we normally do. When we walk, we don't think, okay, right calf contract, left calf contract. No, you just generate those rhythmic movements.
And of course, there's no reason for them to get stronger or larger in response to those movements. Let's say you were to do a kind of strange experiment of attaching 30 pound weights to your ankles and you were to do those movements. Well, if you weren't specifically contracting your calves in each step, there's no reason for the calves to take on the bulk of the work. And you would distribute that work across your hip flexors and other aspects of your musculature. Your whole nervous system seeks to gain efficiency, it seeks to spread out the effort.
So you can nest this as a principle for yourself, which is if you want to get stronger, it's really about moving progressively greater loads or increasing the amount of weight that you move. Whereas if you're specifically interested in generating hypertrophy, it's all about trying to generate those really hard almost painful localized contractions of muscle. Now, of course, how much weight you use in order to generate those contractions will also impact hypertrophy. But I think most people don't really understand the mind muscle connection.
It sounds like a great thing, but it's actually one of the things you want to avoid if your goal is simply to become more supple or to become stronger. You want to do the movements properly and safely, of course but it's the opposite of hypertrophy where with hypertrophy you're really trying to make that particular muscle, sometimes two muscles, do the majority if not all the work. Whereas in moving force loads in trying to generate activity of any kind like lifting a bar, doing a chin up or something, those so-called compound movements involve a lot of muscle groups.
If your goal is to be better at those, you want to avoid isolating any one particular muscle. Now I know this probably comes across as a kind of a obvious duh, especially to the folks who have spent a lot of time in the gym aimed at getting hypertrophy. But I think most people don't appreciate that it's the nerve to muscle connections and the distinction between isolating nerve to muscle connections versus distributing the work of nerve to muscle connections that's vital in determining whether or not you generate hypertrophy isolated nerve to muscle contractions, versus strength and offsetting strength loss, which would be distributed nerve to muscle connections. If ever there was an area of practical science that was very confused, very controversial and almost combative at times, it would be this issue of how best to train.
I suppose the only thing that's even more barbed wire of a conversation than that is how best to eat for health. Those seem to be the two most common areas of online battle. And the scientific literature has a lot to say about both of those things. Again, my sources for what I'm about to tell you are professor Andy Galpin and colleagues.
I know there are other excellent people out there in the field, but I really trust his work. He does very controlled studies. He spent a lot of time in this space and what's really exciting is that in just the last three years or so, there's been a tremendous amount of information to come out about the practical steps that one can take in order to maximize the benefits of resistance exercise of any kind.
So I'm going to talk about those and I'm going to talk about the research. I will provide some links, both to a couple of the more in-depth tutorials from Dr. Galpin, as well as some of the papers that the information I'm about to tell you stems from.
There's a lot of information saying that you need to move weights that are 80 to 90% of your one rep maximum or 70% are cycle that for three weeks on and then go to more moderate weights. There are a lot of paths, as some people say, there are a lot of ways to add up numbers to get 100. There's a near infinite number of ways to add up different numbers to get to a 100. And what's very clear now from all the literature that's transpired and especially from the literature in this last three years, is that once you know roughly your one repetition maximum, the maximum amount of weight that you can perform an exercise with for one repetition in good form, full range of motion that it's very clear that moving weights or using bands or using body weight, for instance in the 30 to 80% of one rep maximum that is going to be the most beneficial range in terms of muscle hypertrophy and strength. So muscle growth and strength. And there will be a bias, if you're moving weights that are in the 75%, 80% range or maybe even going above that 85 and 90%, you're going to bias your improvements towards strength gains, this is true.
And if you use weights that are in the 30% of your one repetition, maximum or 40% or 50% and doing many more repetitions, of course, then you are biasing towards hypertrophy and what some people like to call muscle endurance, but that's a little bit of a complicated term because endurance, we almost always think of as relating to running or swimming or some long bouts of activity. So 30 to 80% of one repetition maximums, it doesn't really seem to matter for sake of hypertrophy, except at the far ends when you're really trying to bias for strength. Now it is clear however that one needs to perform those sets to failure where you can't perform another repetition in good form again or near to failure. And there's all sorts of interesting nomenclature that's popping up all over the internet, some of which are scientific, some of which is not scientific about how you are supposed to perceive how close you were to failure, et cetera. But there are some very interesting principles that relate to how the nerves connect to the muscles that strongly predict whether or not this exercise that you're performing will be beneficial for you or not.
So here's how it goes. For individuals that are untrained, meaning they have been doing resistance exercise for anywhere from zero, probably out to about two years. Although for some people, it might be zero to one year, but those are the so-called beginners, they're sort of untrained. For those people, the key parameter seems to be to perform enough sets of a given exercise per muscle per week. The same is also true for people that had been training for one or two years or more.
What differs is how many sets to perform depending on whether or not you're trained or untrained. So let's say you're somebody who's been doing some resistance exercise kind of on and off over the years and you decide you want to get serious about that for sake of sport or offsetting age related declines in strength, the range of sets to do in order to improve strength to activate these cascades in the muscle ranges anywhere from two, believe it or not to 20 per week. Again, these are sets per week and they don't necessarily all have to be performed in the same weight training session. I'll talk about numbers of sessions.
So it appears that five sets per week in this 30% to 80% of the one repetition maximum range getting close to failure or occasionally actually going to full muscular failure, which isn't really full muscular failure but the inability to generate a contraction of the muscle or move the weight in good form. I'll go deeper into that in a moment. But about five sets per week is what's required just to maintain your muscle. So think about that. If you're somebody who is kind of averse to resistance training, you are going to lose muscle size and strength, your metabolism will drop, your posture will get worse. Everything in the context of nerve to muscle connectivity will get worse over time unless you are generating five sets or more of this 30% to 80% of your one repetition maximum per week.
So what this means is for the typical person who hasn't done a lot of weight training, you need to do at least five sets per muscle group. Now that's just to maintain. And then there's this huge range that goes all the way up to 15 and in some case, 20 sets per week. Now how many sets you perform is going to depend on the intensity of the work that you perform. This is where it gets a little bit controversial, but I think nowadays most people agree, and Dr. Galpin confirmed that 10%, not to be confused with the 10% we discussed earlier, but 10% of the sets of a given workout or 10% of workouts overall should be of the high-intensity sort where one is actually working to muscular failure.
Now I say not true muscular failure because in theory, you have a concentric movement which is the kind of lifting of the weight and then you have the ecentric portion of muscle contraction, which is the lowering. And ecentric movements because of the way that muscle fibers lengthen and that sliding, actin myosin that we talked about before, you're always stronger in lowering something than you are in lifting it. But the point being that most of your training, most of your sets should be not to failure.
And the reason for that is it allows you to do more volume of work without fatiguing the nervous system and depleting the nerve to muscle connection in ways that are detrimental. So we can make this simple, perform anywhere from five to 15 sets of resistance exercise per week and that's per muscle and that's in this 30 to 80% of what your one repetition maximum. That seems to be the most scientifically supported way of offsetting any decline in muscle strength if you're working in the kind of five set range and in increasing muscle strength when you start to get up into the 10 and 15 set range. Now the caveat to that is everyone varies and muscles vary in terms of their recover ability. Depending on how well you can control the contraction of muscles deliberately and you can actually figure that out by sort of marching.
You might take five minutes and just kind of march across your body and mentally try and control the contractions of muscles in a very deliberate way to the point where you can generate a hard contraction. And you may have to move a limb in order to do this, by the way, I'm not talking about just mentally contracting your bicep without moving your wrist. I'm talking about doing that without any weight in hand or any band or any resistance. If you can generate a high intensity contraction using these upper motor neuron to lower motor neuron pathways to muscle, you might think, "Well, I should perform many more sets." But actually the opposite is true. If you can generate high intensity muscular contractions using your brain, using your neurons, it will take fewer sets in order to stimulate the muscle to maintain itself and to stimulate the muscle in order to grow or get stronger.
So the more efficient you are in recruiting motor units, remember Henneman's size principle, the recruitment of more motor units which isn't just muscles, it's nerve to muscle connections. The better you are at doing that, the more you will recruit these so-called high threshold motor units, the ones that are hard to get to, the more you will kick off the cascades of things within muscle that stimulate muscle growth and strength. So if you have muscles that are challenging to contract, it's going to take more sets in order to stimulate the desired effect in those muscles, not fewer. If you have muscles that you are very good at generating force within, it's going to take fewer sets.
Now how many sets, you are going to have to determine that. It's going to depend. For those of you that are using like 50% of your one repetition, maximum because you're doing a lot of repetitions, you might find that three or four, five sets will maintain the muscle.
You might decide to do that once at one point in the week and then do it again. So if you're going for 10 sets a week, you can divide that among two sessions, you can do that all in one session. The data really show it doesn't matter. There are some differences in terms of whether or not you're trying to generate maximum intensity within a workout or whether or not you want to spread that out. But in general resistance workouts of any kind tend to be best favored by workouts that are somewhere between 45 minutes and 60 minutes. And generally not longer than 60 minutes because that's when all the things like cortisol and some of the inflammatory pathways really start to create a situation in the muscle and in the body that's not so great for you.
So it's not a hard and fast rule, that the ax doesn't drop at 60 minutes but it's pretty clear that performing this five to 15 sets per week, whether or not it's in one workout or whether it's divided up across multiple workouts is really what's going to be most beneficial. And please do keep in mind Henneman's size principle and the recruitment of motor units. And remember the better you are at contracting particular muscles in an isolating those muscles, the fewer sets likely you need to do in order to get the desired effect. Now, what about people who have been training for a while? If you're somebody who's been doing weight training for awhile, the data point to the fact that more volume can be beneficial, even for muscles that you are very efficient at contracting. Now, the curve on this, the graph on this begins again at about five sets per week for maintaining a given muscle group and extends all the way out to 25 or 30 sets per week. However, there are individuals who for whatever reason, can generate so much force, they're so good at training muscles that they can generate so much force in just four or six or eight sets that doing this large volume of work is actually going to be counterproductive.
So everyone needs to figure out for themselves first of all, how often you're willing to do resistance exercise of any kind. And again, it doesn't matter if you're using bands or weights or body weight. For instance, if you're doing chin-ups, chances are unless you are very strong, that you're not using weights, you're just using something that you can hold onto or if you're doing pushups, some of you will be working in that 30 to 80% of your one repetition maximum range.
It doesn't necessarily mean that you have to be moving weights in a gym for instance. So the purpose here is to figure out what muscles you're trying to train. That's an issue that we'll talk about in a moment. And then it does appear that somewhere between five and 15 sets per week is going to be the thing that's going to work for most people. Now, this is based on a tremendous amount of work that was done by Andy Galpin and colleagues, Brad Schoenfeld and colleagues and others, Mike Roberts. There's a huge group of people out there doing exercise physiology and a small subset of them that are linking them back to real-world protocols that don't just pertain to athletes.
So that's mainly what I'm focusing on today. And surely there will be exceptions. Now, if you're going to divide the sets across the week, you're not going to do all 10 sets for instance for a given muscle group in one session, then of course it's imperative that the muscles recover in between sessions.
And we are going to talk about recovery both at the systemic level, the whole nervous system and at the local level, the nerve to muscle and local even muscle lev