in: Fitness, Health & Fitness, Podcast

• Last updated: January 30, 2023

Podcast #866: Move the Body, Heal the Mind

When we think about the benefits of exercise, we tend to think of what it does for our body, making us leaner, stronger, and healthier. But my guest is out to emphasize the powerful effect physical activity has on our brains too, and just how much our bodies and minds are connected.

Dr. Jennifer Heisz is a professor, the director of the NeuroFit Lab which studies the effects of exercise on brain health, and the author of Move the Body, Heal the Mind. Today on the show, Jennifer and I first discuss how physical activity can help treat mental disorders. She shares the way that low to moderate intensity exercise can mitigate anxiety, and how short bouts of intense exercise can be used as exposure therapy for treating panic disorders. We also talk about the phenomenon of inflammation-induced depression, and how exercise can alleviate it. And Jennifer shares how exercise can strengthen someone’s attempt at sobriety, as well as prevent addiction in the first place. From there, we turn to the way exercise can not only mitigate mental maladies but actually optimize the mind. Jennifer shares how physical activity fights aging, and can enhance your focus and creativity. We discuss how exercise can improve your sleep, how it can be used to shift your circadian clock, and whether it’s okay to work out close to your bedtime.

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Read the Transcript

Brett McKay: Brett McKay here and welcome to another edition of The Art of Manliness podcast. When we think about the benefits of exercise, we tend to think of what it does for our body, making us leaner, stronger and healthier, but my guest is out to emphasize the powerful effect physical activity has on our brains too, and just how much our bodies and minds are connected. Dr. Jennifer Heisz, is a professor, the Director of the NeuroFit Lab, which studies the effects of exercise on brain health and the author of Move the Body, Heal the Mind. Today on the show, Jennifer and I first discuss how physical activity can help treat mental disorders. She shares the way that low to moderate intensity exercise can mitigate anxiety and how short bouts of intense exercise can be used as exposure therapy for treating panic disorders. We also talk about the phenomenon of inflammation-induced depression and how exercise can alleviate it, and Jennifer shares how exercise can strengthen someone’s intent at sobriety as well as prevent addiction in the first place. From there, we turn to the way exercise can not only mitigate mental maladies but actually optimize the mind. Jennifer shares how physical activity fights aging, it can enhance your focus and creativity. We discussed how exercise can improve your sleep, how it can be used to shift your circadian clock and whether it’s okay to work out close to your bed time.

After the show’s over, check out our show notes at

All right, Jennifer Heisz. Welcome to the show.

Dr. Jennifer Heisz: Thanks so much for having me.

Brett McKay: So, you are the director of the NeuroFit Lab at McMaster University in Canada. What do you research at the NeuroFit Lab?

Dr. Jennifer Heisz: Yeah, my lab studies the benefits of exercise for brain health, so we look at the benefits of exercise for mental health, cognition and in the prevention of Alzheimer’s disease.

Brett McKay: And how do you start with exploring that connection between physical activity and our mental health?

Dr. Jennifer Heisz: So, it was back in graduate school, I was studying the fundamentals of neuroscience, so how does the brain represent who we are as people and our memories. And it became really clear to me that something was not quite right with my own brain. I was having some pretty severe anxiety, some intrusive thinking. And I went to the doctor, they recommended I try an antidepressant. I was very reluctant, and then a friend recommended I try cycling and magically, those bike rides soothed my mind, they quieted my mind and it really had a profound shift, not just in my personal life, giving me a lot of peace, but also in my professional life because I became fascinated with understanding how exercise was having such a profound effect on the brain. And so that’s where it all began, back in grad school, and we’ve been intensely studying it ever since.

Brett McKay: And this idea of there’s a connection between our bodies and our mental health, it’s been going on for, I would say, 50 years. But this is a break from Descartes who said, famously said, “The brain and the mind are separate, the body is just the machine, and there’s a soul inside the machine and the body doesn’t really have effect on the mind.” But what the research is showing us now, we are our minds, our bodies, our minds.

Dr. Jennifer Heisz: Yeah. Oh gosh, Descartes, he did a lot of damage. It was important, the mind-body dualism that he set forth, because prior to that, the body was really mystified, a spiritualized, religious, and the study of it couldn’t take place. So he had to kind of separate the mind and the body kind of spirit and body to advance medicine, but in doing so, he removed basically the shoulders up from the study of medicine for such a long time that we don’t really… We don’t fully understand how the brain works and we don’t fully understand how to take care of our mind, what the biological bases are of mental health, but yes, you’re right. We are absolutely paving the way. New research is very exciting and we’re starting to piece things together.

Brett McKay: So you got a book out, it’s called Move the Body, Heal the Mind, where you make a very reader-friendly summary of this research you’ve been doing at your lab and you explore how exercise and physical activity can help different types of mental health issues. And the first one is anxiety, and I’m sure all of us have read the articles or heard the podcast about how anxiety is on the rise in the West, what does your research show about exercise’s effect on anxiety?

Dr. Jennifer Heisz: So exercise has a really profound effect on reducing anxiety symptoms, and the effects are felt immediately after we exercise, so you go up for your workout and in that acute phase, as soon as you’re done, when you’re like, “Done.” That gives us a huge reprieve in our anxiety levels, but even if we consistently go back to exercise, we get less and less anxious. Now, there’s kind of an interesting play here with intensity of exercise. So, when you’re feeling especially anxious, if you’re already in a stressful situation in life, for example, then intensive workouts may not be the best mode to go to because the exercise stress will add on to the stress in your life and vigorous exercise as you know, mimics the symptoms of anxiety. So your heart will race, it’ll be difficult to breathe, and for a lot of people, this can create a panic attack situation where the heart is racing so fast that they’re afraid they’re gonna have a heart attack. When it comes to exercising for anxiety, just kinda check in with yourself, because sometimes too intense is not good, and the research shows that at that low to moderate…

Intensity, you can really get a lot of benefits. And the reason why is these lighter intensity exercises release this neuro chemical called neuropeptide Y and essentially, this is a resiliency factor that bays the brain, it bays the fear centers, the amygdala and helps to essentially quiet those centers down. So it’s having this biochemical effect to give you the anxiety relief.

Brett McKay: Yeah, the neuropeptide Y, I’ve read studies where they’ve looked at Navy SEALs and I think they typically have more neuropeptide Y than the general population. It might be a genetic thing and they’re just being selected for that inadvertently, but you’re saying that exercise, even if you don’t have Navy SEAL levels of neuro-peptide Y, it can increase it. Is that increased immediate?

Dr. Jennifer Heisz: Yeah, the increase happens immediately after and it lasts for about 30 minutes afterwards. Now, the research done so far has only shown that you have to do the exercise to get the boost. In neuropeptide Y, there’s no kind of residual effects over the long-term, so this is why consistency is key, so that every workout that you put in, you get that boost. Now, the cool thing about the Navy SEAL studies, is that not all Navy SEALs have this abundance of neuropeptide Y and the ones that don’t have as much, they’re the ones most likely to develop post-traumatic stress disorder. So this is really a protective factor for the brain against trauma and stress.

Brett McKay: Okay, so you get the immediate boost of neuropeptide Y when you exercise, and that can help. And if you do excise consistently, it can stave off anxiety or mitigate it. Is there anything else that goes on with exercise that helps prevent anxiety in the long run? Let’s say you do some intense exercise when you’re not in a state of stress, does that have any type of an effect on long-term anxiety?

Dr. Jennifer Heisz: Yeah, absolutely. When we think about the stress response, a lot of anxiety stems from a maladaptive stress response. And the stress response is this balancing act between the sympathetic nervous system, that fight or flight response, and the parasympathetic nervous system or the rest and digest. And when we use exercise in a state of calm, essentially we’re training up our stress response, so we’re activating the sympathetic nervous system when we’re vigorously going. And then as soon as we stop, we are flexing our parasympathetic nervous system, that rest and digest, so that it becomes stronger and better able to help us recover from stress. And so by continuously hitting the stress system with exercise, we can actually strengthen our stress response, not just for exercise stress, but for all stressors in our life. And so ultimately, what happens is that when we experience a stressful situation in our life, yeah, it will activate the sympathetic nervous system but our parasympathetic nervous system will be really strong and better able to engage so that we stay more calm and less reactive.

Brett McKay: Okay, now also mentioned in the book, you’ve also done research, there’s been research done on, let’s say someone’s got severe anxiety and they’re actually getting talk therapy for it, exposure therapy. Combining them with exercise can actually give that a boost, correct?

Dr. Jennifer Heisz: Oh yeah, that’s a super cool finding. Now, this is a bit tricky. People with severe anxiety or panic disorder, before I was talking about how anxiety symptoms really mimic the symptoms of vigorous exercise, the heart racing, difficulty breathing, difficulty concentrating. This vigorous exercise is actually can as an exposure therapy for people who have panic disorder. Most people with panic disorder, they avoid exercise, they hate it, they especially avoid vigorous exercise because it evokes those symptoms that they fear the most. So there’s this anxiety sensitivity that makes them really sensitive to vigorous exercise. But it turns out that vigorous exercise is the medicine that they need, but in really short baby doses, for example, one way to micro-dose intense exercise into their life would be just doing a few seconds of sprint. And the idea is that it exposes them, so you sprint all out for a few seconds and your heart immediately picks up, it’s difficult to breathe, you stop, and everything comes back down, and you realize you’re safe. But it gives you that exposure to those symptoms that you fear the most, and you over time with the repetition of this, the exposure of this, eventually those symptoms lose their power and control over you, and you’re not afraid of them anymore, and that then transfers into the panic disorders that you feel in your life.

Brett McKay: That’s really interesting. And I imagine too, besides the neuropeptide Y increasing and strengthening the parasympathetic systems, but I imagine exercise, just moving your body gets you out of your brain. And part of the problem with anxiety is, you’re just worried about stuff that’s not really happening, and moving your body takes you away from that and kinda gets you back into just the present.

Dr. Jennifer Heisz: Oh yeah, 100%. So the mind, it has one track, we can only think about one thing at a time, and when our heads a mess with anxiety, we’re focused on negativity, and just getting the mind to think on something else like the breath, this is meditative techniques, often focus on the attention to the breath. But you can couple that with exercise, so attention to movement, attention to breath, you don’t just have to be sitting still, you can be moving and it doesn’t just have to be yoga, it could be running or weightlifting, the point is you’re focusing on the here and now, and it’s grounded in the body.

Brett McKay: Okay, so for anxiety, to prevent anxiety, reduce it in the long run, do that intense stuff ’cause it’s going to make you more resilient. But if you’re feeling stressed out right now, take it easy ’cause that might just add to the stress, so maybe a walk, for example, would be the thing you’d wanna do.

Dr. Jennifer Heisz: Perfect, yeah, that would be great.

Brett McKay: Okay, let’s talk about another issue that’s been on the rise in the West, and that’s depression. And you start the book talking about the usual response from many general practitioners, you had this experience yourself, if you go on, you’re just like, “Man, it’s been a couple of weeks, I’m just feeling gray, I’m just feeling really down.” All the GP will say, “Well, here’s an antidepressant.” Why were you hesitant to take the antidepressant and what are some of the problems of relying on antidepressants to treat depression?

Dr. Jennifer Heisz: Yeah, I was reluctant to take the antidepressant partly because these drugs have a profound effect on the whole brain, not just for the intended benefit to reduce depression. And I was pretty scared of what alterations would take place, and so I wanted to just at least explore alternatives, and for me, fortunately, my symptoms were mild. Some people don’t have that luxury, their symptoms may be too severe and they need immediate help, and the antidepressant can be really beneficial and transformative for some people. So, I wanna make sure that that message is clear that it’s not… I’m not anti-antidepressants, but I do think that having options is really important for people. The first line of defense for most general practitioners or doctors is to prescribe an antidepressant, and we’ve seen that on the rise, especially for mild forms of depression that may benefit from other alternatives like exercise. And so, I think it’s important that we educate our medical practitioners on the benefits of these other therapies and equip them with the tools. I don’t think it’s their fault. I just don’t think that they’re trained. They’re trained really to prescribe drugs for ailments, and so I think that it really…

It comes back to Descartes actually. There’s bio-medical model, and we need much more of a holistic approach to our health.

Brett McKay: Well, something you talk about in the book is that even when someone is given an antidepressant, they don’t always respond to it, and that’s because depression, it isn’t homogenous. There can be different causes for it, and it may not be a serotonin problem, the depression could be caused by something else. And one of the sources it could be, sources of depression, it could be inflammation. And we actually had a guest on a few years ago talking about the inflammation-depression connection, but can you summarize what we’re discovering about the connection between inflammation and depression?

Dr. Jennifer Heisz: Yeah, it’s super fascinating. And this, I think, is the form of depression on the rise because it’s linked to chronic stress. When we are experiencing chronic stress, as many people have in the last several years, what happens is that the body was never intended to deal with stress at such a chronic level, it was really designed to deal with it acutely, so the predator or whatever the threat would be immediately in the physical environment and then it would either be dealt with or not, and then the stress would go away. Today in modern life, there’s stress after stress after stress, day after day after day, we worry, which creates more stress, the uncertainty of situations create even more stress, and so this chronicity, this chronic stress that we’re facing day in and day out is really damaging the body.

And what it does, is it starts to damage the cells, physically damage the cells, and this launches a sterile immune response. And so it’s sterile because there’s no bacteria or virus in the body, it’s just the damaged cells from the stress, and so the immune system launches an attack against these damaged cells, this elevates inflammation, and that inflammation doesn’t just stay in the body, but it can start infiltrating into the brain. And when the brain has too much inflammation, it creates a lot of problems for the natural functioning of the neurons and so, things don’t function as well, and this can lead to dysfunctions in neuro-chemicals, but it can also lead to slowing of processing, brain fog, depressed mood, and there’s the source of depression. Not necessarily coming from the root cause of something you’re born with a biochemical deficit in serotonin production or some other neurochemical, but a lifestyle, the chronic stress of life is damaging the body in ways that are affecting the mood.

Brett McKay: Yeah, when you’re sick, think about that, when you’re sick, not only do you feel bad, but you get depressed. You just wanna hunker down in a blanket, and so it kinda makes sense that there’s a connection there. When you feel depressed, you don’t wanna do anything. When you’re sick, you don’t wanna do anything.

Dr. Jennifer Heisz: Yeah, yeah, and that’s an evolutionary advantage because if you’re kind of anti-social and your home alone in bed, you’re not gonna spread the bacteria or virus around. And so that was actually an evolutionary advantage, but now, if inflammation is being caused not by a bacteria or virus but rather stress, then that advantage is no longer, and instead it just looks like major depressive disorder.

Brett McKay: Are we are able to screen for inflammation caused depression?

Dr. Jennifer Heisz: Well, technically, yes. The research suggests that certain cytokines, these pro-inflammatory cytokines can actually, are elevated more in people who have depression, especially drug-resistant depression, TNF alpha is one of them. However, it’s certainly not routine clinical practice, even though we’ve known about this research for about 10 years. Again, we need to catch up the medical community to some of the newer research on mental illness and how to treat it.

Brett McKay: One thing they’ve discovered with people with inflammation-caused depression is that exercise helps. But this is counter-intuitive, because exercise is a stressor, it causes inflammation. If you do a heavy weight lifting session, your muscles get inflamed to repair the damage you’ve done. So how can something that causes inflammation reduce inflammation to help reduce depression?

Dr. Jennifer Heisz: So this is a beautiful thing about exercise. You’re right. You go out for a hard run or a vigorous workout, and the body has an acute inflammatory response. And this is to protect your body while you’re pushing it hard. But as soon as you stop, the exercising muscles then release these myokines that essentially act like an inflammatory clean-up crew. These anti-inflammatory cytokines then make the body… They clean up all that inflammation that you produce from exercising and then some, so that over time, your body becomes less and less inflamed. And this is such a really interesting way that we can kind of re-balance, create homeostasis back in the body when it comes to inflammation.

Brett McKay: That’s interesting. When we had the podcast guest about inflammation depression, he was researching sauna use to reduce inflammation ’cause it’s… You heat your body up and it causes inflammation and it can reduce inflammation in the long run.

Dr. Jennifer Heisz: Yeah, it’s… I think all of these sort of acute microdosing of stress, like the cold showers or the holding of the breath or the sauna, the hot exposure or exercise, they’re all micro-challenging the body in a way that creates this counter-response, and then over time, that counter-response, the recovery from stress becomes stronger and makes the body more resilient to stressors. So I think they’re all kind of working with a similar mechanism on the stress response, which is super cool.

Brett McKay: In your lab, have guys found of a particular type of exercise works best for depression or is it any type of exercise?

Dr. Jennifer Heisz: Yeah. So the research has a pretty interesting, clear benefits. So when it comes to aerobic exercise, we’re really talking like every step counts, and the longer that you go, the better. So every additional 10 minutes that you add onto your aerobic exercise, you get an additional boost in mood up to one hour. When it comes to resistance exercising like weight lifting or yoga, Tai chi, the more intensive you are with the weights or the resistance, the bigger the benefit there when it comes to depression.

Brett McKay: Interesting. Okay. Let’s move onto another issue some people are struggling with, and that’s addiction. How can exercise help in addiction recovery?

Dr. Jennifer Heisz: So when someone gets addicted to a substance, what happens is that the substance is addictive because it increases dopamine in the brain to supernatural levels. And what ends up happening is this… The reward system within the brain ends up locking down, so it strips away receptors. And what this does is it makes it really difficult to get enough dopamine response from natural things in life. So they’re no longer rewarding, they no longer induce that feeling of reward. And so what ends up happening is that when an addict then gains tolerance and dependency on the substance of abuse. Now, when they enter sobriety, what ends up happening is that, okay, now they’ve taken away that supernatural dopamine, and all they’re left with is the natural stimuli in the world that induces just a small amount of dopamine. And it’s not enough, at least at first, because the brain needs to recover, and it will recover, which is a really fascinating, amazing feature of the brain, that it heals itself, but it takes time. And exercise, because it releases dopamine as well, can help speed that up. So it helps speed up the healing process, it helps crush cravings within that first few weeks of sobriety, and it can be a real helpful tool for people who are in recovery.

Another super beneficial effect of exercise for addiction recovery is, especially if you’re exercising with a group, it creates a brand new social circle for you to have additional support. And for most recovering addicts, they’ve lost a lot of their friends because they were all tied up with the addiction and the drug use. And so building this new community of support and friendship through exercise has been extremely beneficial for a lot of recovering addicts.

Brett McKay: Okay. Just to make sure I understand. So when you take a really strong drug, you basically blast your dopamine receptors, correct? And it’s just like…

Dr. Jennifer Heisz: That’s right.

Brett McKay: Right. And so to get the feeling back, you have to take more and more of the addictive substance, whatever. What you’re saying, when we stop the addictive substance, it gives our brain a chance for those dopamine receptors to get back to a normal state. And exercise can just help that process along. Is that how it works?

Dr. Jennifer Heisz: Yeah.

Brett McKay: Okay. And then you also talk about how exercise can actually be a great way to prevent addictions, correct?

Dr. Jennifer Heisz: Yeah. And this is, again, back to the idea that exercise is a form of reward and can give the brain the dopamine that it seeks. So teenagers are especially experimental. They’re seeking novelty and new experiences. And in fact, there’s even a theory that suggests that that’s by design. The brain is just hungry for new experiences, and this helps them to explore the environment around them, to understand what the world is like, and then they’re better equipped to function in it. And so exercising helps provide the brain the dopamine that it seeks within these novel rewarding experiences. And if exercising is not there or these novelty experiences are not there, then there is a temptation to… A greater temptation to go seeking dopamine out in less helpful situations like in alcohol and drugs of abuse.

And so the research is really fascinating on that for teens, for young people who are more active, they’re less likely to experiment with drugs of addiction, drugs of abuse, they’re less likely to become addicted. And so, yeah, it seems to be really beneficial. But there is this really interesting study I like that… It contrasted the different forms of education that we give students and young people about drugs. So there’s the anti-drug campaign, Just Say No To Drugs, This is your brain on drugs, that kind of, Don’t do drugs campaign, versus teaching kids how to live a healthy lifestyle that includes physical activity. And what the research found was that kids are less likely to try and experiment with drugs if they’ve been educated on a healthy lifestyle rather than when they’ve been educated to do the anti-drug campaign. Because if you think about it, when I was a teen, if you told me not to do something, I was just more curious about why I wouldn’t… Why I wasn’t supposed to do it? And so this… To me, this makes a lot more sense, and having that exercise there as part of that healthy lifestyle gives the brain the dopamine that it craves.

Brett McKay: We’re gonna take a quick break for a word from our sponsors. And now back to the show. Okay. So let’s talk about another thing you were focusing… You don’t just focus on preventing mental illness, mental health issues, but you wanna use exercise as a way to help people have a more fulfilling life in all aspects in their life. And one thing you’ve found is that exercise can help in the aging process. What does exercise do to keep our brains young?

Dr. Jennifer Heisz: Yeah. So exercise has an incredible effect on the aging brain. So it essentially helps keep our brain young. So as we get older, we… Well, the brain, even through adulthood, can produce new… Brand new neurons, brand new born neurons within the hippocampus, which is critical for memory and learning, and it’s also the brain region that’s devastated by Alzheimer’s disease. So by creating more new neurons there, we boost our memory, keep our brain sharp and young and help prevent Alzheimer’s disease.

Brett McKay: Well, it also increases this substance BDNF, is that what it is?

Dr. Jennifer Heisz: Mm-hmm. Yeah.

Brett McKay: Yeah, what is BDNF?

Dr. Jennifer Heisz: So BDNF, Brain-Derived Neurotrophic Factor, and this is a growth factor that helps support the survival functioning of these brain cells. And I like to think of it as like a fertilizer. So it helps them really thrive, the brain cells really thrive and function well. And exercise produces brain BDNF, Brain-Derived Neurotrophic Factor. And there’s this super cool new research out, primarily it’s been shown in animal models, and we’re trying to bring it into human models in my lab now, but it’s looking at this link between lactic acid or lactate and BDNF. So lactate is produced by the muscles when they get into that anaerobic state. When we’re in an anaerobic state, what happens is lactate starts to accumulate, and the accumulation of that lactate spills out into the blood, it travels to the brain, reporting directly to the hippocampus, and there, it produces… It, sorry, activates BDNF, which then can help fertilize and fortify the cells there. So it’s a really fascinating link between higher intensity exercise and the lactate that it produces, and then this growth factor, BDNF, that actually helps to support brain cells.

Brett McKay: Okay. So it can… Exercise can help neurogenesis along. Has there been studies that show that it can help prevent or reduce our risk for dementia?

Dr. Jennifer Heisz: Mm-hmm. Yeah. So research from my lab, we did a head-to-head comparison between genetic risk factors and physical inactivity. And there’s a genetic risk factor, APOE4, it’s an allele that puts people at an elevated risk. And about 25% of the population has it. And we compared that genetic risk to physical inactivity and found that people who were physically inactive had a similar risk of developing dementia as those who were genetically predisposed. So it’s… I have this saying, You can’t change your genes, but you can change your lifestyle, and it can have as big of an effect on your dementia risk as your genetic profile. So we often think about dementia as being sort of a biological disease, but we do have a lot of control. And this simple thing of moving the body can actually help prevent that.

Brett McKay: And you also found in your research too, going back to the social component of exercise, that it can… If you add in sociability into exercise, it actually turbo-charges the age benefits, correct?

Dr. Jennifer Heisz: Yeah. It’s really cool. So the… Especially for older adults who can suffer from loneliness and social isolation, exercise provides this social benefit. And there’s this cool study, I really like it, it showed that older adults who work out together have better health benefits than those who work out alone, even if the ones who are working out together are not working out as hard. [chuckle] So it really highlights the benefits that we get from being with others. And I think the last couple years has been a testament to how important social connections are. And exercise is such a catalyst for creating those social connections.

Brett McKay: So another thing that people wanna be better at, at least I do sometimes… Oftentimes, is I wanna be able to focus better. I’m at work, I’m just… I feel distracted. And your labs actually found research that exercise, physical activity, can help with focus. What does that research say?

Dr. Jennifer Heisz: Yeah. So basically, most of us do our work sitting or with little movement. And when we sit for prolonged periods of time, essentially, the brain gets starved of vital nutrients that it needs to really think and focus. And so every 30 minutes, get up for a two-minute movement break. It doesn’t have to be anything vigorous. It could just be a stretch, walk around the office, walk around the room, go get a drink of water. That subtle movement from sitting to standing and then moving a little bit is enough to help increase brain blood flow, especially to the prefrontal cortex. So the prefrontal cortex is our most evolved brain region in humans, and it is… It’s governing all of that focused attention that we need to inhibit distractions and stay on task. And it needs a lot of blood flow, it needs a lot of energy in the form of glucose and oxygen. And so we can give it that through exercise. And research in my lab, we’ve shown that these short exercise breaks can actually help students prevent them from mind wandering during class so they can stay on task better, and then when you’re on task, you’re remembering things later, so that they perform better on their tests afterwards.

Brett McKay: We’ve had guests on the podcast talking about the need to revive physical education in schools, ’cause a lot of schools… I don’t know how it is in Canada, but here in the United States, they’ve pulled back on PE because they wanna spend more time studying for these state-mandated tests. But some schools have found… Well, actually, when they had the kids spend more time doing vigorous exercises, vigorous play, scores go up.

Dr. Jennifer Heisz: Yeah. It’s counter-intuitive. And I think that a lot of parents and school administrators think that, okay, we just need to cram in more knowledge and information. But the brain needs to be primed to accept that knowledge, and exercise helps to prime it, so it’s ready for learning, and then it can learn better and learn more efficiently and more effectively. So it’s something that we’re really pushing here.

Brett McKay: Yeah. So I think the dose you gave in the book for focus is, for kids, they need 60 minutes of vigorous movement. So just like they get out of breath and sweaty, basically. I think it’s like five times or seven… Every day is ideal, correct, isn’t it, for young kids? And then if when you’re a teenager, it’s like three to four days is the minimum effective dose?

Dr. Jennifer Heisz: Yeah. And I think I’m not a stickler on getting the maximum. I just want people to move more. I don’t wanna put too much stress on parents. They already have a lot of stress. But just moving more, it accumulates throughout the day. Get it in. And so just focusing on that, and being mindful of how much you’re sitting and for how long, and breaking up that sedentary time is really important.

Brett McKay: What about creativity? Is there a connection between creativity and physical activity?

Dr. Jennifer Heisz: Yeah, yeah. So this is really cool. So the brain… I talked about the prefrontal cortex. And it kinda has these two modes. So one of its mode is focused. It inhibits distraction, and we call that inhibitory control. The second mode is this mental flexibility, which is kind of like daydreaming, mind wandering, creative thinking, thinking divergently, outside the box. And so it has these two modes. And when we sit and stay focused for so long, what ends up happening is that that mode gets super tired and it can’t do that very well, and then it just kind of does unproductive thinking. But when we exercise, what happens is we can switch the context. So we switch our context from sitting and focusing to exploring the environment, which flips the switch to that mental flexibility. And this… It’s sort of the idea of when you’re moving in space and doing something different, it’s very interesting to the brain, and you can kind of… In states of flow, for example, when it’s challenging, but you’re in the moment, you can actually couple these two different modes so that they’re actually both on at the same time. And this gives you the most powerful brain function possible. [chuckle]

Brett McKay: So you’re a cyclist, you run, you do the triathlon stuff. When you’re on a run or a long cycle, do you get a lot of ideas for your work?

Dr. Jennifer Heisz: Oh, yeah, yeah. For sure. Yeah. The best ideas come when I’m on my run. And so it’s like you’re uninhibited by focus thinking. The idea is that when we’re kind of free to allow our mind to wander, then it gets more access to the deep repertoire within our brain that may not have bubbled up to the surface if we’re just focused on one single point, one single stream of thought. So it just opens up the channels. [chuckle] And the research shows this… When we look at different sports, certain sports are better able to unleash that creativity. So net and combat sports that have an opponent and they involve this improvisation and this play between you and an opponent, this creates a lot more creativity within the individual than, say for example, gymnastics or figure skating, which require you to memorize a predefined set of moves. So there’s less creativity involved in that. And the idea is that when we train our body to move more creatively, we train our brain to think more creatively. And so even if you’re not into sports, you can apply this to your own workout program by changing things up. So take a different walking route or try a different activity, even if it’s just for fun. These additional things, these novelty experiences that we add to our life help the brain to stay in that flexible mode.

Brett McKay: Another connection you found in your lab to our quality of life is exercise and sleep. What’s the connection there?

Dr. Jennifer Heisz: Yeah, so exercise is so beneficial for sleep. It’s one of the greatest gifts that gives. And so it works kind of two ways. So exercising during the day, it helps us expend more energy, when we expend more cellular energy, like ATP, it produces this byproduct called Adenosine, and adenosine is a natural sleeping aid, so when adenosine builds up to a certain threshold, it triggers sleep. And so when we move more during the day, we build up more adenosine and we can, we can sleep better at night. We sleep deeper at night. The other way that exercise works is that it can help retrain or re-synchronize brain time to real-time. We’ve all experienced this when traveling through different time zones. That jet lag that you experience when your brain time is just really out of sync with real time and it just takes some time to kind of realign the two. Well, exercising can help speed that realignment up. We know that the sun is a really powerful cue of what time it is for the brain, and the brain can kinda link up with the sun but exercising actually has similar qualities as the sun does to help reset the suprachiasmatic nucleus, that masterclock within the brain to help, to help us sync up our time better.

Brett McKay: Okay. So if you’re having trouble sleeping, exercise during the day.

Dr. Jennifer Heisz: Yeah.

Brett McKay: Is there a time that’s best for that to get the benefits of exercise and sleep?

Dr. Jennifer Heisz: Yeah, so some people may have heard, it’s bad to exercise at night and the research shows actually, it’s okay, as long as you’re not going super vigorously to the point that your heart rate’s still elevated 25 beats above baseline when you’re about to go to sleep, that’s sort of the key. But if you… A lot of people like to work out just before they go to bed, and if it’s not… If you’re able to get your heart rate back down before you sleep, then it will be very beneficial, but there’s this cool research that was done, they used these micro-ultra-short sleep cycles where they’d have people sleep for one hour, wake for one hour, and do that for three days straight to just wipe out the circadian clock, and then they would introduce exercise at different times of the day to see how it impact, how it would shift the clock. And what they found was that if you’re someone who likes to stay up late and you need to start getting up earlier, and you need to shift your clock a bit earlier, then exercising first thing in the morning around 7: AM is beneficial, but if you’re someone who needs to sleep in more and stay up a bit later then exercising in the early evening is best for them.

Brett McKay: So I think a lot of people might be listening to this and thinking, “Yeah, I know, I gotta exercise more, not only for my physical health but yeah and not my mental health.” But man, it’s really hard to get going, it’s hard to stick to a routine, and your lab has actually researched why people struggle to start and stick with an exercise program. What have you all found?

Dr. Jennifer Heisz: Yeah, I mean, it’s hard. It is hard, the brain is against us. It’s kind of this relic of the evolutionary past when we needed to conserve energy to survive, and so when we weren’t expending energy to survive, to hunt and gather our food, then the brain was just like, “Okay, let’s just chill. Let’s just be lazy here.” But now we don’t have to really move to survive, at least most of the time, there’s no imminent danger, no need to hunt and gather our food, and so the brain sees voluntary exercise as an extravagant expense, and it goes out of its way to prevent us from doing it, that negative talk me when, “Oh, I’m too tired. Oh, we don’t have time to do it.” This is just that brain trying to conserve energy, and so there are certain things you can do to kind of remind yourself that resources are plenty of… A really fun trick is to swish some sugary drink in your mouth, and the trick is you don’t actually even have to drink it, you can just swish it around and spit it out, and that actually helps to reduce the effort you feel when you’re first starting your work out to essentially break the inertia and remind the brain that resources are plenty, but I think it’s also important to remember that it is harder to move when we’re not mentally well.

So at the very beginning of the pandemic, we conducted some research, we surveyed 1600 people, asking them, “How are you doing? What’s your physical activity like?” And not surprisingly, people were really… They were stressed, they were more depressed, they were more anxious, their activity level was down, people who are able to be active, they were faring better, but and people shifted why they wanted to be active, so instead of being active to physically look good, they were trying to be active to feel better mentally, but there was this mental health paradox where they wanted to work out for their mental health, but their mental health was getting in the way, so they were too stressed or anxious to exercise, and they lacked the motivation, which is a symptom of depression.

And so we created a tool kit, it’s available on my website, and basically, it goes over some evidence-based tips, but essentially it’s like, keep in mind, in those states, some is better than none, consistency is key, and it’s back to this idea that, yeah, there are these benchmarks that we wanna meet in terms of what’s best for the brain and body, but every little bit counts and some movement is better than no movement, especially when it comes to your mental health, and so taking a much more compassionate approach to exercising and taking off the intensity and putting in the time, I personally found this to be really beneficial.

Like you said, during the pandemic, I had been… I had started training for this Ironman and I had… Prior to the pandemic, I had been going out training pretty vigorously, but once the pandemic hit and the uncertainty of the situation, it caused so much personal stress in my life that when I would go out for these long runs or these vigorous runs, I would start panic, my body would go into this panic attack mode, and so I had to learn to just essentially take off the intensity, so I’d put in the time, but it wasn’t at that intensity that I was used to, because I wasn’t in that same mental state as I had been before, and so doing these check-ins with your body is really important and being just really compassionate with yourself and understanding that it is really… When it comes to your life and your health and your well-being, consistency is really the goal.

Brett McKay: Okay, so yeah, the takeaway there, if you’re having a hard time getting started with an exercise program, change your mind of what an exercise program has to look like. I think a lot of people think, “Well, it’s gotta be an hour long of intense… ” Whatever, it doesn’t have to be. Like if it is, if you get 60 minutes of day walking and it’s broken up in 15 minutes throughout the day, start there, and also make sure you pick something you enjoy, if you…

Dr. Jennifer Heisz: That’s right, yeah.

Brett McKay: If you hate marathon running, don’t do that, but you’re not gonna do that.

Dr. Jennifer Heisz: Don’t do that. That’s right, absolutely.

Brett McKay: Well, this has been a great conversation. Where can people go to learn more about the book and your work? ‘Cause in your book what’s great, besides all this research you highlight, you also provide some starter templates for people for exercise programs, so where can they learn more about that?

Dr. Jennifer Heisz: Yeah, so my book’s called Move the Body, Heal the Mind. You can order it anywhere. Books are available for purchase. I have a website that gives some background on the book, And I had mentioned my NeuroFit Lab website. I’m on Instagram dr.jenniferheisz, follow me there or on Twitter @jenniferheisz.

Brett McKay: Fantastic. Well, Jennifer Heisz, thanks so much for your time. It’s been a pleasure.

Dr. Jennifer Heisz: Thank you so much.

Brett McKay: My guest today was Dr. Jennifer Heisz. She’s the author of the book, Move the Body, Heal the Mind. It’s available on and bookstores everywhere. You can find more information about her work at her website, Also, check out our shownotes at You can find links to resources where you can delve deeper into this topic.

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