How to Build Endurance in Your Brain & Body

The episode opens with the host introducing himself as Andrew Huberman, a professor of neurobiology and ophthalmology at Stanford School of Medicine, and stating that the podcast is separate from his teaching and research roles there. He places this episode within a series on physical performance and skill learning. The previous four episodes covered learning skills faster, gaining strength, losing fat faster by leveraging the nervous system (including shiver and non-shiver thermogenesis), hypertrophy, sets and reps, cold ice bath protocols, and how the body makes ATP from carbohydrates or fats.

He says the plan had been to move to a new topic, but listeners asked many questions about endurance, which he calls vitally important for physical performance and for both short-term and long-term health. He asks strength athletes and people uninterested in endurance to keep listening, because some ways to train endurance turned out to be "very different than I would've previously imagined." The promised content covers some science, the four types of endurance, and protocols for training them alongside weight training, skill training or yoga, as well as tools aimed at endurance athletes.

The topic of endurance, I think, has been badly misrepresented, frankly, online, and when you start digging into the science and you start talking to real experts in this area, what you discover, what I've discovered, is that it's an incredibly interesting area because it teaches us so much about how our body and our brain use fuels and how we can control which fuels are used by our body and brain.

Hydration is previewed as a central later topic. The host argues there is a right and a wrong way to hydrate and promises a formula for matching water intake to activity level. He calls the common advice to drink "until your urine runs clear" wrong. He also states that improper hydration can produce "20 to 30% reductions in performance," whether in strength, hypertrophy, running, swimming or mental performance. This section does not give the source behind that figure. He frames the protocols as things listeners can apply "if you deem those correct and safe for you."

The rest of the opening is housekeeping. All episodes are collected at hubermanlab.com, where the site can be searched by topic, such as creatine, sleep, ice bath or sauna. The site also offers sign-up for the free Huberman Lab Neural Network newsletter, which carries protocols, PDFs and announcements, including possible future live lectures. The Huberman Lab Instagram account is mentioned as another place where protocols are posted.

Before turning to endurance, the host repeats one point from the previous episode. Anyone who wants to build muscle strength or size, or just keep the muscle they already have, should do "at least five sets of resistance training per muscle per week." Without that, he says, "we lose muscle over time," and he gives this as one reason among many to keep a regular resistance-training routine.

He presents keeping muscle as important for long-term health and function, including being able to get up from a chair or off the ground. He says the resistance can come from body weight, bands, weights, or lifting rocks or logs in the yard. He states his strong belief that resistance training matters for systemic physiology and overall health, "and that includes our brain health," and refers listeners to the previous episode for the mechanisms and for details on sets, reps, proximity to failure, and whether to do cardiovascular training before or after weight training.

Endurance is defined broadly as the ability to engage in "continuous bouts of exercise, or continuous movement, or continuous effort of any kind." The host presents a belief, not a demonstrated result in this section, that physical endurance training carries over to long-duration mental effort, and promises to explain at the end of the episode why there is reason to think a biological crossover exists. He rejects the simpler idea that people who train only for short, intense strength and speed efforts can only do short, intense bouts of mental work.

He then states that cardiovascular exercise, meaning a heart rate kept up continuously for a period of time, and endurance exercise are "vital" for enhancing aspects of biology in the body and brain so that the brain can perform focused work and learning for longer. The stated structure is a little science followed by protocols.

The science section begins with ATP, which the host describes as required for anything that takes energy or effort, including thinking, talking, walking and running. He describes mitochondria as organelles that act as "little factories that make energy," and says humans can convert many things into ATP.

Using a piece of pizza as the example, he explains that food is broken down into fatty acids from the fats and glucose from the bread, and cells then convert these into ATP through processes such as glycolysis and lipolysis. He notes that muscles and neurons use different fuel sources to generate ATP.

He describes the fuels in roughly the order they are used. Phosphocreatine, which exists naturally in muscle and is the reason people supplement with creatine, powers short, intense efforts, such as the first push on a stalled car. With continued effort, the body uses blood glucose and then glycogen stored in the liver, which he likens to a packed lunch. Fat stored in adipose tissue is another reserve. He says that even someone at 3% or 5% body fat can extract fatty acids from it for conversion to ATP.

Fuel sources the host lists as usable to generate energy regardless of diet: creatine; glucose; glycogen; lipids; ketones, for people who are ketogenic.

The second key point is that converting these fuels into energy "most of the time" requires oxygen, which comes in through the mouth and nose, reaches the lungs, and is distributed through the bloodstream. Oxygen is not itself a fuel. The host compares it to the oxygen a fire needs: without it the logs cannot burn, and with more of it they catch and burn. "Oxygen allows you to burn fuel."

The host frames sustained effort, whether a run, a swim or studying, as requiring both energy and oxygen. He then moves the question of endurance from willpower to biology: "Willpower is neurons. It's neurons in our brain." He describes a "central governor" that decides whether to continue or quit. He claims that whether a person shows resilience or quits early and cannot handle frustration "has to do with your fuel utilization in specific neurons." This section does not present evidence for that claim.

He argues the more useful question is what limits performance, or what makes someone decide to stop, whether after a hard day, an easy day, or simply out of laziness. He says this question gets to "the heart of motivation and fuel use, motivation and fuel allocation," and that understanding what stops us will show what lets us start and continue an effort.

He names five categories that enable effort: nerves (neurons), muscle, blood, heart and lungs. He says he does not want to "completely write off" the immune system and other systems, but focuses on these five "because that's where most of the data are." He credits exercise physiologist Dr. Andy Galpin, a full professor who does muscle biopsy research and works with recreational and professional athletes, as the person he consulted for the episode, while noting he also read other literature. He promises to mention a key review for readers who want more detail, though it is not named in this section.

To support his claim that quitting is a mental rather than physical event, the host describes a study published "a couple years ago" in the journal Cell. As he presents it, the study identified a class of neurons in the brainstem that, when they shut off, lead to quitting. These neurons release epinephrine (adrenaline). He explains that the locus coeruleus, a small group of neurons at the back of the brain, releases epinephrine throughout waking hours, releases more under stress, and acts as an alertness or "readiness signal" for the whole brain. Epinephrine levels are low during relaxation and falling asleep.

In the experiment as he describes it, subjects made efforts to move toward a goal while the researchers altered the visual surroundings with moving stripes, like fences passing on both sides. By changing how fast the stripes moved, they could make subjects feel either that their effort was moving them forward or that it was futile, even when the subjects were working hard. He compares this to walking on a treadmill whose belt will not move, or putting great effort into a virtual reality task while seeming to move "excruciatingly slow."