How Exercise Affects the Brain and Learning | Dr. Andrew Huberman

0:02Most all of the studies, yes, most all

0:05of the studies that have explored the

0:06relationship between exercise, brain

0:08health, and longevity and performance

0:10find positive effects.

0:12Now, for some of you who are skeptics,

0:14you might be thinking, well, great, so

0:16you can do any form of exercise? Well,

0:18in some sense, yes. I'll actually tell

0:20you this right off the bat.

0:22There are good data showing that if

0:23people do 6-second sprints, max all-out

0:27sprints on a stationary bicycle followed

0:30by 1 minute rest

0:33and repeat that six times you see

0:36significant acute effects on brain

0:39performance. So, the brain performance

0:42could be a memory task, sometimes it is

0:43a memory task. It could be what's called

0:45a Stroop task, which is a cognitive

0:46flexibility task where you have to

0:48distinguish between the colors that

0:50words are written in and the content of

0:52the words. Okay, so-called Stroop task.

0:53I've talked about this on previous

0:54podcasts. I'll talk about it a little

0:55bit more later. Regardless of the

0:57cognitive test that's used, that very

0:59short duration high-intensity training

1:01increases performance significantly.

1:04As well 20 or 30 minutes of so-called

1:07steady-state cardio, you know, figuring

1:09out how fast you can run or row or swim

1:12or stationary bike

1:14for 20 to 30 minutes at a steady state

1:17and then you analyze people's cognitive

1:19performance on a memory task. It can be

1:21a working memory task, so remembering a

1:22short string of numbers, or it could be

1:24math problems, it could be the Stroop

1:25task, any number of different tasks

1:27reveal the same thing, which is that the

1:29longer duration lower intensity cardio

1:31also significantly improves performance.

1:34Now, does that mean that you can do

1:37six rounds of 6 seconds of sprinting

1:39with a minute in between or

1:4120 minutes of cardiovascular exercise

1:43and get the same effect on brain

1:44performance? Well, if you're just

1:46looking at overall improvements in

1:48performance, so for instance, the

1:50percentage of information that you learn

1:52if you do or you don't do the exercise

1:54or if you compare those two forms of

1:55exercise that I just mentioned

1:57In that sense, yes, it really doesn't

1:59make a difference. Which may have you

2:00scratching your head, but in a few

2:01moments, I'll explain why that is.

2:04On the other hand, different forms of

2:06exercise, of course, impact our bodily

2:08health differently. Higher intensity,

2:10shorter duration exercise, of course,

2:12impacts things like VO2 max and which

2:14circulating hormones and neuromodulators

2:16are going to be present very differently

2:18than longer duration, lower intensity

2:19exercise. So, too, if you have people do

2:23single joint isolation resistance

2:24training training exercises, like a

2:27single leg leg extension or

2:29both legs leg extension versus

2:3110 sets of 10 in a squat exercise,

2:33you're going to see very different

2:35specific adaptations at the physical

2:37level, at the bodily level.

2:39But in every case,

2:41where you explore the acute, the

2:43immediate changes that occur in brain

2:45output and function

2:47after people do that sort of exercise,

2:49you're going to see significant

2:51increases. When one does physical

2:53exercise, short duration, high intensity

2:55cardio, or higher intensity resistance

2:58training, single joint training,

3:00compound training,

3:02single joint isolation exercises,

3:03compound exercises, one sees these

3:05increases in brain performance, at least

3:08acutely in the immediate stage after the

3:10training. So, we have to ask ourselves,

3:12why is it

3:13how is it

3:14that all these different forms of

3:16exercise are positively impacting brain

3:19performance? And the answer is very

3:21simple and fortunately gives us

3:24tremendous leverage over our exercise

3:27and how to impact our brain health. And

3:29the answer is

3:31arousal. However,

3:33the answer isn't entirely arousal,

3:35meaning not all of the positive effects

3:37of exercise on brain health longevity

3:39and performance can be explained by

3:41arousal. But when I step back from the

3:43literature, again, an enormous

3:44literature, tens of thousands of

3:46peer-reviewed papers, many of which are

3:47done exceptionally well, by the way, as

3:49well as meta-analyses and reviews,

3:52I think it's fair to say that probably

3:5460%

3:56of the effects of exercise on brain

3:58health, performance, and longevity can

4:00be explained by the specific shifts in

4:02our physiology, both bodily physiology

4:05and directly within the brain's

4:07physiology during those bouts of

4:09exercise, which is this increase in

4:12so-called autonomic arousal, which

4:13occurs during the exercise, but also

4:16extends into a window after the exercise

4:19is completed.

4:21about this relationship between

4:22exercise, arousal, and acute brain

4:25performance, meaning the improvements in

4:27brain performance that happen

4:28immediately after the exercise. And then

4:30we'll shift our focus to the effects of

4:32exercise that occur more chronically,

4:34that is the effects of exercise on brain

4:37health and performance that occur in the

4:39hours, days, weeks, and years after we

4:41exercise, even if we are continuing to

4:43exercise every day or three times a week

4:46or whatever the frequency might be.

4:49But, this issue of arousal is extremely

4:51important, and I assure you it's not

4:52trivial. In fact, it will help you

4:54understand a number of things in the

4:56domains of deliberate cold exposure,

4:57stress, trauma, and most importantly for

5:00today's discussion, it will help you

5:02design an exercise program that's geared

5:04towards giving you the maximum bodily

5:07health effects and the maximum brain

5:09health effects. There are a couple of

5:11different ways you can increase

5:12so-called autonomic arousal or levels of

5:14alertness. Sometimes it's called stress,

5:16but autonomic arousal is simply an

5:18increase in the amount of activity in

5:20the so-called sympathetic arm of the

5:21autonomic nervous system, which is nerd

5:23speak for more alert, more aroused,

5:25wide-eyed,

5:26ready to move,

5:28higher heart rate, higher blood

5:29pressure, more alertness. Increasing

5:31autonomic arousal improves learning and

5:33memory. Now, it's also very important to

5:36understand that that increase in

5:38autonomic arousal can improve learning

5:40and memory if the autonomic arousal

5:42occurs after the exposure to the

5:44material. Most people find that a bit

5:45surprising. I certainly did when I first

5:47read this paper. It makes sense if you

5:49start to think about the persistence of

5:50memories for things like traumas or bad

5:53events, right? Bad event happens and

5:54there's this big spike in cortisol and

5:56adrenaline and those memories are hard

5:58to eradicate. They're certainly hard to

5:59remove the emotional content from.

6:01And if you think about it, in those

6:03instances, the event happens and then

6:05comes the big increase in cortisol and

6:07adrenaline. So, that maps very well onto

6:09the study that I'm describing here.

6:11In addition, however, lots of studies

6:14have shown that increasing autonomic

6:16arousal as measured by increases in

6:18adrenaline or cortisol or both or any

6:20number of different measures of

6:22autonomic arousal

6:25that occurs during the exposure to the

6:27new material. Okay, so this isn't

6:29trauma. This is like new math material,

6:31new history material, new music

6:33material, new motor skill material

6:36that you're trying to learn.

6:38Increases in autonomic arousal that

6:40occur as you're trying to so-called

6:41encode the information, you're being

6:43exposed to that new information, also

6:45significantly improve learning. And it's

6:48always through increases in arousal. In

6:51other words,

6:52whether or not you're measuring

6:53cortisol, adrenaline, heart rate, blood

6:55pressure, galvanic skin response, how

6:58wide someone's pupils are, or small

7:00someone's pupils are, or any combination

7:03of those things, or any other measures

7:04of autonomic arousal, the consistent

7:06takeaway is increases in arousal during

7:10or after, in particular after,

7:13trying to learn a certain material

7:16is going to improve significantly the

7:18amount of material that one learns, the

7:20details of that material, and the

7:22persistence of that learning over time.

7:25Okay, so now we've established that

7:26elevated levels of autonomic arousal

7:29either during

7:30or after, and indeed also before about

7:33of learning, the so-called encoding

7:35phase of learning when we're exposed to

7:37the new material that we want to learn

7:38and remember, are all beneficial. This

7:41is wonderful news when we look out on

7:44the whole of the literature on the

7:45relationship between exercise and brain

7:48health and performance, we see studies

7:50that incorporate exercise either before

7:52or after a bout of learning. And we also

7:55find studies, believe it or not, that

7:57combine exercise with learning in real

7:59time, literally exposing people to new

8:01material that they're expected to learn

8:03or trying to learn while they're walking

8:05on a treadmill or running on a treadmill

8:07or cycling or rowing. Yes, those studies

8:09have also been done, although for

8:10practical reasons

8:12they're not as numerous as the studies

8:14exploring the relationship between

8:15exercise and learning where the exercise

8:18is done before or after the bout of

8:20learning. Okay, so what this means is

8:22wonderful. What this means is that if

8:24you want to use exercise not just for

8:26enhancing your bodily health, but also

8:28for brain health and performance, you

8:30can do that exercise before, during, or

8:33after bouts of learning. That allows you

8:35to look at the constraints of your life.

8:37For instance, are you one of these

8:38people that can get up at 5:00 or 6:00

8:40or 7:00 a.m. and exercise before

8:42everyone else gets up or before your

8:44work day starts or your school day

8:46starts,

8:47do a round of exercise and then get into

8:49your bouts of learning, whatever that

8:51material may be, or are you somebody who

8:53has to dive into the work day, school

8:54day, family obligations, et cetera, in

8:57which case you might only be able to

8:58exercise later in the day, but you're

9:00probably still somebody who would like

9:01to enhance their brain health and

9:03performance. So, in that case you might

9:04organize the thing that you're trying to

9:06learn, the encoding or the exposure to

9:08the thing that you're trying to learn

9:09either in written form, so you're

9:11reading or you're listening to it or

9:13you're attending a class or classes and

9:15then exercising after you're exposed to

9:17that material in order to get that

9:19elevated levels of arousal not unlike

9:21the arrangement of the studies that I

9:22was talking about earlier, which used

9:25the ice exposure

9:27in order to generate increases in

9:29arousal and thereby to improve learning

9:31and memory. So, in the show note

9:33captions for this episode, we've batched

9:35a number of different references that

9:37have explored the relationship between

9:38exercise and cognitive performance.

9:41And across those studies

9:43and the ones that are referenced

9:44therein, you'll find studies where the

9:46exercise bout was done before, where the

9:48exercise bout was done during, where the

9:51exercise bout was done after a round of

9:53learning or encoding of information.

9:56And I should mention that different

9:57studies focus on different cognitive

9:59tasks. So, exercise and the arousal

10:01associated with exercise has been shown

10:03to acutely improve

10:06recall, so just raw recall of material,

10:08the details in material.

10:11It's been shown to improve cognitive

10:12flexibility through things like the

10:14Stroop task. And so, in a very

10:15convenient way, exercise has been shown

10:18to acutely improve performance on all

10:21those sorts of brain and memory tasks,

10:24which is greatly reassuring to all of us

10:26because what it means is that it

10:28probably doesn't matter so much when you

10:30do your exercise or what it is that

10:31you're trying to learn. It's going to be

10:33beneficial as long as the thing that

10:35you're trying to learn and the exercise

10:37are positioned fairly closely in time.

10:39Now, all of this is focused, of course,

10:41on the relationship between exercise and

10:43brain function at the acute level, the

10:45immediate level. It's fair to say that

10:47all high-intensity exercise and

10:48resistance training is going to support

10:51brain function in the chronic sense, in

10:52the long-term sense. In fact, the

10:54literature points to that. And once

10:56again, I've batched the references for

10:57this episode so that they're grouped

10:59together according to the specific

11:00topics and timestamps.

11:02And the two studies that I recommend you

11:03look at if you're interested in this

11:05relationship between high-intensity

11:06training and cognitive function, in

11:08particular executive function, that

11:10cognitive flexibility I was talking

11:11about earlier, such as in the Stroop

11:13task, there's a wonderful article

11:14entitled Executive Function after

11:17exhaustive ex-