How Exercise Affects the Brain and Learning | Dr. Andrew Huberman
00:00:00.000 | [Silence]
00:00:02.500 | Most all of the studies, yes, most all of the studies
00:00:05.980 | that have explored the relationship between exercise,
00:00:08.380 | brain health and longevity and performance,
00:00:10.260 | find positive effects.
00:00:12.460 | Now, for some of you who are skeptics,
00:00:14.540 | you might be thinking, well, great,
00:00:15.940 | so you can do any form of exercise.
00:00:17.860 | Well, in some sense, yes,
00:00:19.660 | I'll actually tell you this right off the bat.
00:00:22.060 | There are good data showing
00:00:23.740 | that if people do six second sprints,
00:00:26.260 | max all out sprints on a stationary bicycle
00:00:30.340 | followed by one minute rest and repeat that six times,
00:00:35.340 | you see significant acute effects on brain performance.
00:00:40.860 | So the brain performance could be a memory task.
00:00:43.380 | Sometimes it is a memory task.
00:00:44.820 | It could be what's called a Stroop task,
00:00:46.220 | which is a cognitive flexibility task
00:00:47.740 | where you have to distinguish between the colors
00:00:50.300 | that words are written in and the content of the words.
00:00:52.700 | Okay, so-called Stroop task.
00:00:53.860 | I've talked about this on previous podcasts.
00:00:55.220 | I'll talk about it a little bit more later.
00:00:56.620 | Regardless of the cognitive test that's used,
00:00:58.700 | that very short duration, high intensity training
00:01:01.580 | increases performance significantly.
00:01:04.620 | As well, 20 or 30 minutes of so-called steady state cardio,
00:01:09.020 | you know, figuring out how fast you can run or row or swim
00:01:12.380 | or stationary bike for 20 to 30 minutes at a steady state.
00:01:17.060 | And then you analyze people's cognitive performance
00:01:20.120 | on a memory task.
00:01:20.960 | It can be a working memory task,
00:01:22.060 | so remembering a short string of numbers,
00:01:24.100 | or it could be math problems.
00:01:25.260 | It could be the Stroop task.
00:01:26.180 | Any number of different tasks reveal the same thing,
00:01:28.940 | which is that the longer duration, lower intensity cardio
00:01:31.660 | also significantly improves performance.
00:01:34.700 | Now, does that mean that you can do six rounds
00:01:38.460 | of six seconds of sprinting with a minute in between
00:01:40.820 | or 20 minutes of cardiovascular exercise
00:01:43.620 | and get the same effect on brain performance?
00:01:46.100 | Well, if you're just looking at overall improvements
00:01:48.780 | in performance, so for instance,
00:01:50.220 | the percentage of information that you learn
00:01:52.580 | if you do or you don't do the exercise,
00:01:54.180 | or if you compare those two forms of exercise
00:01:56.140 | that I just mentioned, in that sense, yes,
00:01:58.460 | it really doesn't make a difference,
00:02:00.200 | which may have you scratching your head.
00:02:01.560 | But in a few moments, I'll explain why that is.
00:02:04.220 | On the other hand, different forms of exercise, of course,
00:02:07.300 | impact our bodily health differently.
00:02:09.940 | Higher intensity, shorter duration exercise, of course,
00:02:12.580 | impacts things like VO2 max and which circulating hormones
00:02:15.940 | and neuromodulators are going to be present very differently
00:02:18.340 | than longer duration, lower intensity exercise.
00:02:21.000 | So too, if you have people do single joint isolation
00:02:24.540 | resistance training exercises,
00:02:26.980 | like a single leg leg extension
00:02:28.340 | or both legs leg extension,
00:02:30.460 | versus 10 sets of 10 in a squat exercise,
00:02:34.020 | you're going to see very different specific adaptations
00:02:36.620 | at the physical level, at the bodily level.
00:02:39.420 | But in every case where you explore the acute,
00:02:43.100 | the immediate changes that occur in brain output
00:02:46.300 | and function, after people do that sort of exercise,
00:02:49.920 | you're going to see significant increases.
00:02:52.000 | When one does physical exercise,
00:02:53.980 | short duration, high intensity, cardio,
00:02:56.380 | or higher intensity resistance training,
00:02:59.760 | single joint training, compound training,
00:03:02.180 | single joint isolation exercises, compound exercises,
00:03:04.980 | one sees these increases in brain performance,
00:03:07.900 | at least acutely in the immediate stage after the training.
00:03:11.100 | So we have to ask ourselves, why is it?
00:03:13.580 | How is it that all these different forms of exercise
00:03:16.980 | are positively impacting brain performance?
00:03:20.640 | And the answer is very simple.
00:03:22.720 | And fortunately, gives us tremendous leverage
00:03:25.920 | over our exercise and how to impact our brain health.
00:03:29.400 | And the answer is arousal.
00:03:32.520 | However, the answer isn't entirely arousal,
00:03:35.640 | meaning not all of the positive effects of exercise
00:03:38.280 | on brain health, longevity, and performance
00:03:40.400 | can be explained by arousal.
00:03:42.160 | But when I step back from the literature,
00:03:43.640 | again, an enormous literature,
00:03:45.240 | tens of thousands of peer-reviewed papers,
00:03:47.100 | many of which are done exceptionally well, by the way,
00:03:49.420 | as well as meta-analyses and reviews,
00:03:52.200 | I think it's fair to say that probably 60 to 70%
00:03:56.280 | of the effects of exercise on brain health,
00:03:59.040 | performance, and longevity
00:04:00.800 | can be explained by the specific shifts in our physiology,
00:04:03.420 | both bodily physiology
00:04:05.360 | and directly within the brain's physiology
00:04:08.480 | during those bouts of exercise,
00:04:10.400 | which is this increase in so-called autonomic arousal,
00:04:13.600 | which occurs during the exercise,
00:04:15.720 | but also extends into a window
00:04:18.160 | after the exercise is completed.
00:04:20.320 | So we have to talk about this relationship
00:04:22.140 | between exercise, arousal, and acute brain performance,
00:04:25.620 | meaning the improvements in brain performance
00:04:28.120 | that happen immediately after the exercise.
00:04:30.720 | And then we'll shift our focus to the effects of exercise
00:04:33.360 | that occur more chronically.
00:04:34.960 | That is the effects of exercise on brain health
00:04:37.320 | and performance that occur in the hours, days, weeks,
00:04:40.560 | and years after we exercise,
00:04:42.520 | even if we are continuing to exercise every day
00:04:45.400 | or three times a week or whatever the frequency might be.
00:04:49.080 | But this issue of arousal is extremely important,
00:04:51.640 | and I assure you, it's not trivial.
00:04:53.120 | In fact, it will help you understand a number of things
00:04:55.900 | in the domains of deliberate cold exposure, stress, trauma,
00:04:59.760 | and most importantly for today's discussion,
00:05:01.520 | it will help you design an exercise program
00:05:04.120 | that's geared towards giving you
00:05:05.600 | the maximum bodily health effects
00:05:08.120 | and the maximum brain health effects.
00:05:10.960 | There are a couple of different ways
00:05:12.160 | you can increase so-called autonomic arousal
00:05:14.560 | or levels of alertness.
00:05:15.520 | Sometimes it's called stress,
00:05:16.660 | but autonomic arousal is simply an increase
00:05:19.360 | in the amount of activity in the so-called sympathetic arm
00:05:21.680 | or the autonomic nervous system, which is nerd speak for,
00:05:23.980 | more alert, more aroused, wide-eyed, ready to move,
00:05:28.200 | higher heart rate, higher blood pressure, more alertness.
00:05:30.880 | Increasing autonomic arousal improves learning and memory.
00:05:34.600 | Now, it's also very important to understand
00:05:37.120 | that that increase in autonomic arousal
00:05:39.320 | can improve learning and memory
00:05:41.040 | if the autonomic arousal occurs
00:05:43.140 | after the exposure to the material.
00:05:45.020 | Most people find that a bit surprising.
00:05:46.520 | I certainly did when I first read this paper.
00:05:48.440 | It makes sense if you start to think
00:05:49.680 | about the persistence of memories
00:05:51.040 | for things like traumas or bad events, right?
00:05:53.640 | Bad event happens and there's this big spike
00:05:55.520 | in cortisol and adrenaline,
00:05:57.280 | and those memories are hard to eradicate.
00:05:59.040 | They're certainly hard to remove the emotional content from.
00:06:01.960 | And if you think about it, in those instances,
00:06:04.440 | the event happens and then comes the big increase
00:06:06.920 | in cortisol and adrenaline.
00:06:08.240 | So that maps very well onto the study
00:06:10.060 | that I'm describing here.
00:06:11.720 | In addition, however, lots of studies have shown
00:06:14.800 | that increasing autonomic arousal,
00:06:16.760 | as measured by increases in adrenaline or cortisol or both,
00:06:20.720 | or any number of different measures of autonomic arousal,
00:06:23.820 | that occurs during the exposure to the new material.
00:06:28.880 | Okay, so this isn't trauma.
00:06:29.960 | This is like new math material, new history material,
00:06:33.440 | new music material, new motor skill material
00:06:36.600 | that you're trying to learn.
00:06:38.480 | Increases in autonomic arousal that occur
00:06:40.580 | as you're trying to so-called encode the information,
00:06:43.040 | you're being exposed to that new information,
00:06:44.980 | also significantly improve learning.
00:06:47.940 | And it's always through increases in arousal.
00:06:51.260 | In other words,
00:06:52.820 | whether or not you're measuring cortisol, adrenaline,
00:06:55.020 | heart rate, blood pressure, galvanic skin response,
00:06:57.820 | how wide someone's pupils are,
00:06:59.780 | or small someone's pupils are,
00:07:01.820 | or any combination of those things,
00:07:03.660 | or any other measures of autonomic arousal,
00:07:05.740 | the consistent takeaway is increases in arousal
00:07:09.300 | during or after, in particular after,
00:07:13.520 | trying to learn a certain material
00:07:16.060 | is going to improve significantly
00:07:18.200 | the amount of material that one learns,
00:07:20.320 | the details of that material,
00:07:22.320 | and the persistence of that learning over time.
00:07:25.280 | Okay, so now we've established
00:07:26.560 | the elevated levels of autonomic arousal
00:07:29.080 | either during or after,
00:07:31.480 | and indeed also before about of learning,
00:07:34.660 | the so-called encoding phase of learning
00:07:36.400 | when we're exposed to the new material
00:07:38.020 | that we want to learn and remember are all beneficial.
00:07:41.800 | This is wonderful news.
00:07:43.160 | When we look out on the whole of the literature
00:07:45.640 | on the relationship between exercise
00:07:47.760 | and brain health and performance,
00:07:49.400 | we see studies that incorporate exercise
00:07:51.400 | either before or after about of learning.
00:07:54.560 | And we also find studies, believe it or not,
00:07:56.860 | that combine exercise with learning in real time,
00:07:59.940 | literally exposing people to new material
00:08:02.140 | that they're expected to learn or trying to learn
00:08:04.760 | while they're walking on a treadmill
00:08:06.240 | or running on a treadmill or cycling or rowing.
00:08:08.600 | Yes, those studies have also been done,
00:08:10.320 | although for practical reasons,
00:08:12.200 | they're not as numerous as the studies
00:08:14.520 | exploring the relationship between exercise and learning
00:08:17.360 | where the exercise is done before
00:08:19.120 | or after the bout of learning.
00:08:21.040 | Okay, so what this means is wonderful.
00:08:23.000 | What this means is that if you want to use exercise,
00:08:25.820 | not just for enhancing your bodily health,
00:08:28.040 | but also for brain health and performance,
00:08:30.120 | you can do that exercise before, during,
00:08:32.880 | or after bouts of learning.
00:08:35.160 | That allows you to look at the constraints of your life.
00:08:37.400 | For instance, are you one of these people
00:08:39.280 | that can get up at five or six or 7 a.m.
00:08:41.800 | and exercise before everyone else gets up
00:08:44.020 | or before your workday starts or your school day starts,
00:08:47.840 | do a round of exercise
00:08:49.120 | and then get into your bouts of learning,
00:08:51.000 | whatever that material may be?
00:08:52.720 | Or are you somebody who has to dive into the workday,
00:08:54.720 | school day, family obligations, et cetera,
00:08:57.080 | in which case you might only be able
00:08:58.480 | to exercise later in the day,
00:09:00.340 | but you're probably still somebody
00:09:01.500 | who would like to enhance their brain health and performance.
00:09:04.100 | So in that case, you might organize
00:09:05.760 | the thing that you're trying to learn,
00:09:06.960 | the encoding or the exposure
00:09:08.440 | to the thing that you're trying to learn,
00:09:09.760 | either in written forms,
00:09:11.400 | you're reading or you're listening to it,
00:09:13.000 | or you're attending a class or classes,
00:09:15.240 | and then exercising after you're exposed to that material
00:09:18.680 | in order to get that elevated levels of arousal,
00:09:20.840 | not unlike the arrangement of the studies
00:09:22.800 | that I was talking about earlier,
00:09:24.480 | which use the ice exposure
00:09:27.420 | in order to generate increases in arousal
00:09:29.700 | and thereby to improve learning and memory.
00:09:32.600 | So in the show note captions for this episode,
00:09:35.000 | we've batched a number of different references
00:09:37.080 | that have explored the relationship
00:09:38.300 | between exercise and cognitive performance.
00:09:41.480 | And across those studies
00:09:43.120 | and the ones that are referenced therein,
00:09:45.320 | you'll find studies where the exercise bout was done before,
00:09:48.600 | or the exercise bout was done during,
00:09:50.960 | or the exercise bout was done after a round of learning
00:09:54.320 | or encoding of information.
00:09:56.360 | And I should mention that different studies
00:09:57.760 | focus on different cognitive tasks.
00:10:00.200 | So exercise and the arousal associated with exercise
00:10:03.200 | has been shown to acutely improve recall.
00:10:06.760 | So just raw recall of material, the details in material,
00:10:11.040 | it's been shown to improve cognitive flexibility
00:10:13.560 | through things like the Stroop task.
00:10:14.960 | And so in a very convenient way,
00:10:16.980 | exercise has been shown to acutely improve performance
00:10:20.360 | on all those sorts of brain and memory tasks,
00:10:24.140 | which is greatly reassuring to all of us
00:10:26.400 | because what it means is that
00:10:28.640 | it probably doesn't matter so much
00:10:29.880 | when you do your exercise
00:10:31.200 | or what it is that you're trying to learn.
00:10:32.920 | It's going to be beneficial
00:10:34.260 | as long as the thing that you're trying to learn
00:10:36.420 | and the exercise are positioned fairly closely in time.
00:10:39.800 | Now, all of this is focused, of course,
00:10:41.320 | on the relationship between exercise and brain function
00:10:44.480 | at the acute level, the immediate level.
00:10:46.380 | It's fair to say that all high intensity exercise
00:10:48.760 | and resistance training is going to support brain function
00:10:51.840 | in the chronic sense, in the long-term sense.
00:10:53.960 | In fact, the literature points to that.
00:10:55.720 | And once again, I've batched the references
00:10:57.720 | for this episode so that they're grouped together
00:10:59.760 | according to the specific topics and timestamps.
00:11:02.360 | And the two studies that I recommend you look at
00:11:04.280 | if you're interested in this relationship
00:11:05.860 | between high intensity training and cognitive function,
00:11:08.640 | in particular, executive function,
00:11:09.960 | that cognitive flexibility I was talking about earlier,
00:11:12.280 | such as in the Stroop task.
00:11:14.000 | There's a wonderful article entitled
00:11:15.680 | "Executive Function After Exhaustive Exercise."
00:11:18.640 | [upbeat music]
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