Essentials: Build Muscle Size, Increase Strength & Improve Recovery

**Andrew Huberman** (0:00)
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health and performance.
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. 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. 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. All of that is governed by the relationship between the nervous system, neurons, and their connections to muscle. So today, as always, we're going to talk a little bit of mechanism. I'm going to explain how neurons control muscle. 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 blood stream frequently enough and at sufficient levels can help you build and improve the quality of muscle. We are also going to talk about recovery. That's when muscle grows. That's when muscle gets more flexible. None of that actually happens during training. It happens after training. 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 are involved in sitting and standing up. They are involved in lifting objects, including ourselves. They are absolutely essential for maintaining how we breathe. They are 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. Basically, we have upper motor neurons in our motor cortex. So those are in our skull, and those are involved in deliberate 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. 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 the 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 got the upper motor neurons, the lower motor neurons, and for rhythmic movements that are reflexive, you've also got the central pattern generators. I'd like to take a quick break and acknowledge our sponsor, 8 Sleep. 8 Sleep makes smart mattress covers with cooling, heating and sleep tracking capacity. Now I've spoken before on this podcast about the critical need for us to get adequate amounts of quality sleep each and every night. Now one of the best ways to ensure a great night's sleep is to ensure that the temperature of your sleeping environment is correct. And that's because in order to fall and stay deeply asleep, your body temperature actually has to drop about one to three degrees. 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Go to eightsleep.com/huberman to save up to $350 off your Pod4 Ultra. Eight Sleep ships to many countries worldwide, including Mexico and the UAE. Again, that's eightsleep.com/huberman to save up to $350 off your Pod4 Ultra. Today's episode is also brought to us by Element. Element is an electrolyte drink that has everything you need, but nothing you don't. That means the electrolytes, sodium, magnesium and potassium, all in the correct ratios, but no sugar. Proper hydration is critical for optimal brain and body function. Even a slight degree of dehydration can diminish cognitive and physical performance. It's also important that you get adequate electrolytes. The electrolytes, sodium, magnesium and potassium, are vital for the functioning of all the cells in your body, especially your neurons or your nerve cells. Drinking Element dissolved in water makes it extremely easy to ensure that you're getting adequate hydration and adequate electrolytes. To make sure that I'm getting proper amounts of hydration and electrolytes, I dissolve one packet of Element in about 16 to 32 ounces of water when I wake up in the morning, and I drink that basically first thing in the morning. I also drink Element dissolved in water during any kind of physical exercise that I'm doing. They have a bunch of different great tasting flavors of Element. They have watermelon, citrus, et cetera. Frankly, I love them all. If you'd like to try Element, you can go to drinklmnt.com/huberman to claim an Element sample pack with the purchase of any Element drink mix. Again, that's drinklmnt.com/huberman to claim a free sample pack. I'd now 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 amounts of weight in the gym, 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. So there's an important principle of muscle physiology called the Henneman Size Principle. And the Henneman Size Principle essentially says that we recruit what are called motor units. Motor units are just the connections between nerve and muscle from 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. 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. 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 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, too 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 power lifters and the people that like to move heavy weights around will say, no, if you want to get strong, you absolutely have to live 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 use the heaviest weights possible in order to build strength and 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. So this is very reminiscent of neuroplasticity in the brain. 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. Because everything about muscle hypertrophy, about stimulating muscle growth, is about generating isolated contractions, about challenging specific muscles in a very unnatural way.