Most all of the studies, yes, most all of the studies that have explored the relationship between exercise, brain health and longevity and performance, find positive effects. Now, for some of you who are skeptics, you might be thinking, well, great, so you can do any form of exercise. Well, in some sense, yes, I'll actually tell you this right off the bat.

There are good data showing that if people do six second sprints, max all out sprints on a stationary bicycle followed by one minute rest and repeat that six times, you see significant acute effects on brain performance. So the brain performance could be a memory task. Sometimes it is a memory task.

It could be what's called a Stroop task, which is a cognitive flexibility task where you have to distinguish between the colors that words are written in and the content of the words. Okay, so-called Stroop task. I've talked about this on previous podcasts. I'll talk about it a little bit more later.

Regardless of the cognitive test that's used, that very short duration, high intensity training increases performance significantly. As well, 20 or 30 minutes of so-called steady state cardio, you know, figuring out how fast you can run or row or swim or stationary bike for 20 to 30 minutes at a steady state.

And then you analyze people's cognitive performance on a memory task. It can be a working memory task, so remembering a short string of numbers, or it could be math problems. It could be the Stroop task. Any number of different tasks reveal the same thing, which is that the longer duration, lower intensity cardio also significantly improves performance.

Now, does that mean that you can do six rounds of six seconds of sprinting with a minute in between or 20 minutes of cardiovascular exercise and get the same effect on brain performance? Well, if you're just looking at overall improvements in performance, so for instance, the percentage of information that you learn if you do or you don't do the exercise, or if you compare those two forms of exercise that I just mentioned, in that sense, yes, it really doesn't make a difference, which may have you scratching your head.

But in a few moments, I'll explain why that is. On the other hand, different forms of exercise, of course, impact our bodily health differently. Higher intensity, shorter duration exercise, of course, impacts things like VO2 max and which circulating hormones and neuromodulators are going to be present very differently than longer duration, lower intensity exercise.

So too, if you have people do single joint isolation resistance training exercises, like a single leg leg extension or both legs leg extension, versus 10 sets of 10 in a squat exercise, you're going to see very different specific adaptations at the physical level, at the bodily level. But in every case where you explore the acute, the immediate changes that occur in brain output and function, after people do that sort of exercise, you're going to see significant increases.

When one does physical exercise, short duration, high intensity, cardio, or higher intensity resistance training, single joint training, compound training, single joint isolation exercises, compound exercises, one sees these increases in brain performance, at least acutely in the immediate stage after the training. So we have to ask ourselves, why is it?

How is it that all these different forms of exercise are positively impacting brain performance? And the answer is very simple. And fortunately, gives us tremendous leverage over our exercise and how to impact our brain health. And the answer is arousal. However, the answer isn't entirely arousal, meaning not all of the positive effects of exercise on brain health, longevity, and performance can be explained by arousal.

But when I step back from the literature, again, an enormous literature, tens of thousands of peer-reviewed papers, many of which are done exceptionally well, by the way, as well as meta-analyses and reviews, I think it's fair to say that probably 60 to 70% of the effects of exercise on brain health, performance, and longevity can be explained by the specific shifts in our physiology, both bodily physiology and directly within the brain's physiology during those bouts of exercise, which is this increase in so-called autonomic arousal, which occurs during the exercise, but also extends into a window after the exercise is completed.

So we have to talk about this relationship between exercise, arousal, and acute brain performance, meaning the improvements in brain performance that happen immediately after the exercise. And then we'll shift our focus to the effects of exercise that occur more chronically. That is the effects of exercise on brain health and performance that occur in the hours, days, weeks, and years after we exercise, even if we are continuing to exercise every day or three times a week or whatever the frequency might be.

But this issue of arousal is extremely important, and I assure you, it's not trivial. In fact, it will help you understand a number of things in the domains of deliberate cold exposure, stress, trauma, and most importantly for today's discussion, it will help you design an exercise program that's geared towards giving you the maximum bodily health effects and the maximum brain health effects.

There are a couple of different ways you can increase so-called autonomic arousal or levels of alertness. Sometimes it's called stress, but autonomic arousal is simply an increase in the amount of activity in the so-called sympathetic arm or the autonomic nervous system, which is nerd speak for, more alert, more aroused, wide-eyed, ready to move, higher heart rate, higher blood pressure, more alertness.

Increasing autonomic arousal improves learning and memory. Now, it's also very important to understand that that increase in autonomic arousal can improve learning and memory if the autonomic arousal occurs after the exposure to the material. Most people find that a bit surprising. I certainly did when I first read this paper.

It makes sense if you start to think about the persistence of memories for things like traumas or bad events, right? Bad event happens and there's this big spike in cortisol and adrenaline, and those memories are hard to eradicate. They're certainly hard to remove the emotional content from. And if you think about it, in those instances, the event happens and then comes the big increase in cortisol and adrenaline.

So that maps very well onto the study that I'm describing here. In addition, however, lots of studies have shown that increasing autonomic arousal, as measured by increases in adrenaline or cortisol or both, or any number of different measures of autonomic arousal, that occurs during the exposure to the new material.

Okay, so this isn't trauma. This is like new math material, new history material, new music material, new motor skill material that you're trying to learn. Increases in autonomic arousal that occur as you're trying to so-called encode the information, you're being exposed to that new information, also significantly improve learning.

And it's always through increases in arousal. In other words, whether or not you're measuring cortisol, adrenaline, heart rate, blood pressure, galvanic skin response, how wide someone's pupils are, or small someone's pupils are, or any combination of those things, or any other measures of autonomic arousal, the consistent takeaway is increases in arousal during or after, in particular after, trying to learn a certain material is going to improve significantly the amount of material that one learns, the details of that material, and the persistence of that learning over time.

Okay, so now we've established the elevated levels of autonomic arousal either during or after, and indeed also before about of learning, the so-called encoding phase of learning when we're exposed to the new material that we want to learn and remember are all beneficial. This is wonderful news. When we look out on the whole of the literature on the relationship between exercise and brain health and performance, we see studies that incorporate exercise either before or after about of learning.

And we also find studies, believe it or not, that combine exercise with learning in real time, literally exposing people to new material that they're expected to learn or trying to learn while they're walking on a treadmill or running on a treadmill or cycling or rowing. Yes, those studies have also been done, although for practical reasons, they're not as numerous as the studies exploring the relationship between exercise and learning where the exercise is done before or after the bout of learning.

Okay, so what this means is wonderful. What this means is that if you want to use exercise, not just for enhancing your bodily health, but also for brain health and performance, you can do that exercise before, during, or after bouts of learning. That allows you to look at the constraints of your life.

For instance, are you one of these people that can get up at five or six or 7 a.m. and exercise before everyone else gets up or before your workday starts or your school day starts, do a round of exercise and then get into your bouts of learning, whatever that material may be?

Or are you somebody who has to dive into the workday, school day, family obligations, et cetera, in which case you might only be able to exercise later in the day, but you're probably still somebody who would like to enhance their brain health and performance. So in that case, you might organize the thing that you're trying to learn, the encoding or the exposure to the thing that you're trying to learn, either in written forms, you're reading or you're listening to it, or you're attending a class or classes, and then exercising after you're exposed to that material in order to get that elevated levels of arousal, not unlike the arrangement of the studies that I was talking about earlier, which use the ice exposure in order to generate increases in arousal and thereby to improve learning and memory.

So in the show note captions for this episode, we've batched a number of different references that have explored the relationship between exercise and cognitive performance. And across those studies and the ones that are referenced therein, you'll find studies where the exercise bout was done before, or the exercise bout was done during, or the exercise bout was done after a round of learning or encoding of information.

And I should mention that different studies focus on different cognitive tasks. So exercise and the arousal associated with exercise has been shown to acutely improve recall. So just raw recall of material, the details in material, it's been shown to improve cognitive flexibility through things like the Stroop task. And so in a very convenient way, exercise has been shown to acutely improve performance on all those sorts of brain and memory tasks, which is greatly reassuring to all of us because what it means is that it probably doesn't matter so much when you do your exercise or what it is that you're trying to learn.

It's going to be beneficial as long as the thing that you're trying to learn and the exercise are positioned fairly closely in time. Now, all of this is focused, of course, on the relationship between exercise and brain function at the acute level, the immediate level. It's fair to say that all high intensity exercise and resistance training is going to support brain function in the chronic sense, in the long-term sense.

In fact, the literature points to that. And once again, I've batched the references for this episode so that they're grouped together according to the specific topics and timestamps. And the two studies that I recommend you look at if you're interested in this relationship between high intensity training and cognitive function, in particular, executive function, that cognitive flexibility I was talking about earlier, such as in the Stroop task.

There's a wonderful article entitled "Executive Function After Exhaustive Exercise." you