Science Friday
Hosted by Flora Lichtman and Ira Flatow
In a conversation from August, two exercise researchers discuss what physical activity does to mental health—from boosting to straining it.
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I'm Flora Lichtman, and you're listening to Science Friday. Happy Thanksgiving. And today on the podcast, we're already dreading tomorrow, when you might feel like you need to get your steps in. So we're talking about exercise. Besides making you feel better after an indulgent meal, we all know, or at least have heard, that workouts lift your mood, fight depression, make you more resilient when life knocks you down.
But it ain't about how hard you hit. It's about how hard you can get hit and keep moving forward. How much you can take and keep moving forward.
But why exactly does exercise improve mental health? Is it all about those endorphins? Does the type of workout or the duration matter if you're looking for a mental wellness boost? Here to answer those questions and more are Dr. Eduardo Esteban Bustamente. He studies the link between physical activity and mental health in kids as the director of the Healthy Kids Lab at the University of Illinois Chicago. And Dr. Jack Ragland studies exercise and sports science as a professor of kinesiology at Indiana University in Bloomington. Welcome to you both to Science Friday.
Thank you. Glad to be here.
Thanks for having me. Jack, let's start with the basics. We've all heard exercise is good for our mental health. How? Why?
Well, I wish I could definitively answer that question, but truly, we don't know. It's long been thought to be exclusively due to endorphin hormone that our body produces, very similar to morphine and heroin. That certainly can be a part of it, but we know from studies, you can pharmacologically remove it from your system and people still feel better. And there are a host of other biological and hormonal changes that also are likely contributors to that. So my answer would be many things.
Yeah, it's such a big, it's such a big question, you know, why, why does physical activity help with mental health? So I think we started with the data that people who are active have much lower levels of mental illness. So we're talking about a sedentary person might be eight times as likely to have, you know, depression or anxiety versus somebody who's in the highest quintile of activity.
Wow.
In subsequent trials where we randomized people, some people get an exercise program and some people don't, we see pretty nice, consistent, small to moderate benefits of physical activity for mental health. There's just a lot of different ways it'll benefit. If I, if I was gonna bin it in probably three big bins, I think there's this physiological stress of physical activity, there's a host of responses cellularly, molecularly, brain structure and function, that kind of thing. Then you have benefits that are from the context of the physical activity. So for me, doing physical activity programs with kids, I really came to this field fascinated by the idea that, oh, people can be active and it's gonna change the developmental trajectory of kids in terms of brain function and cognition
by virtue of it being kind of like a medicine. But as I've done programs, what I've found is that the relationships are just overwhelmingly powerful. You spend months or years with kids and families and you develop these relationships and you just find so much of the benefit of physical activity program is probably just part of the program, like the quality program, as opposed to just looking at it just like a medicine.
In the sense that if you are part of a community and it's structured and you're doing it for years and years and developing friendships, that matters more than if you, you know, a kid went out there alone for 15 minutes a day and did jumping jacks. Is that what you mean?
Yeah, absolutely. So I think that everything that's mentally healthy for you as you're seated is gonna be mentally healthy for you as you're moving. And the flip side of that is also true. So everything that would probably make you pretty depressed and anxious when you're seated would also probably make you pretty depressed and anxious when you're moving. If you, if you imagine being a kid and you're playing a soccer game and you're working really, really hard, you finally like shoot the final shot, you know, the response of everybody on your team and your coaches really is gonna influence how you're feeling afterwards, you know? If they, if you make it and they all go, wow, you're the best, we love you and we'll always support you, then, you know, you're gonna feel really good. And if they're like, you weren't supposed to take that shot, you missed, you ruined it for all of us, we're never gonna talk to you again, then obviously, you know, that's, that's worse. So this is, this is all at play here.
You said three bins. We've talked about the physiology, the sort of context that you're doing the exercise in.
Yes.
Is there a third bin?
Yeah, I was initially thinking about cognition. There's often a cognitive challenge embedded within games. So in the physical activity world, we have this idea of training specificity. So if I do bicep curls, I'm expecting that my arms will get bigger, but not my legs. And we think the same thing in cognition. So if a game requires a lot of strategy, or inhibition, or working memory, or cognitive flexibility, that specific thing that gets challenged, if people engage with the challenge, adapts.
Jack, you've studied the placebo effect and exercise. How do they fit together?
Well, it relates to what some of what Eduardo said. You don't exercise in kind of a neutral setting. There's social input, there's beliefs, there's past experience. And one aspect of that is expectation, which is one of the drivers of the placebo effect. That if you expect to benefit from an intervention such as exercise, whether that's something that the person already has, or you try to encourage or even manipulate that in an exercise research setting, can often lead to larger psychological, better outcomes than otherwise.
Like if we tell ourselves that exercise is going to make us feel better, it makes us feel even better than exercise alone.
Yes. And the interesting thing is, it does so because your brain neural pathways are being activated. So it sort of amplifies, not always, but often amplifies that sort of beneficial outcome.
Okay, so it's not that you're doing more exercise. You're getting an effect from hearing that it's going to work for you.
Mm hmm. But you know, placebos are affected by social learning. And this, I think, relates to what Eduardo was saying earlier. It's the context. So if you're in a social context where other people are doing the same thing and enjoying it, that can add to the effect. But if you're surrounded by people who don't like what they're doing, or look like they don't like what they're doing, then you're probably not going to experience as much of a benefit as you would compared to that positive context.
Is there any data on duration of exercise and mental health benefits? Like, is the seven-minute workout enough?
There are some studies that show that if you just get up out of your chair and walk down the hall for a minute or so and go back to your chair, that you have increased feelings of energy and it can affect your fatigue. So now, how long that lasts is another factor, but very, very small doses have positive effects. And there's, I think, reasonable evidence that even physical health effects can be generated from very small doses. So it's not the old, you have to do 20 minutes, you have to raise your heart rate to a certain level. We know from a lot of research that you can get by with much less.
Eduardo?
I would add in here that a good way to think about the mental health benefits of physical activity is probably to think about maybe three different categories of benefit. So the first category here might be, say, fidgeting. So if I'm, if I'm working with kids with ADHD, when they're allowed to fidget, we have some evidence to suggest that they're better able to focus on tasks while they're moving. So this is like an instantaneous benefit. As you stop fidgeting, whatever that benefit was, it's, it's gone. The next category here would be an acute bout effect. So acute bout, we just mean single bouts. So you exercise for seven minutes, like you had said, or 10, or 15, or 20, and then you get some transient benefit that's going to last a few hours. And then the
last case would be when people train for months or years. And there, we're hoping for a durable effect, things like brain structure being influenced, higher levels of cognitive function being influenced. For my, my focus literature, which is ADHD, there's a little bit of a Goldilocks effect, where people kind of need to have just the right intensity, just the right duration. Like, if I, if I exercise them too long, or too short, or too hard, or not hard enough, then, you know, you don't see a big jump. But if for kids with ADHD, we're talking maybe 10 to 20 minutes at a, you know, moderate intensity, not too hard, then we see a nice boost in engagement and performance.
It's very similar to what we found in adults. There are also studies that show that as little as three weeks of regular exercise, three times a week, can have a significant benefit for people with moderate clinical depression.
So the chronic effects, at least with some conditions, can emerge fairly early.
Wow. I mean, are there types of exercise that seem better than others for sort of long-term mental health benefits?
Well, first of all, most of the research historically is involved aerobic exercise because researchers were sort of biased towards that. So that works very well, but modest strength training programs work as well. And even very light programs. So the first study that looked at clinical anxiety patients used what they thought was a placebo exercise, which was a stretching mobility program compared to running, and it turned out to be just as beneficial. So the exercise pill that appears to be useful, I would say, is an easy-to-take dose.
We did a meta-analysis recently, which is where we pool all the, all the different physical activity interventions that influence ADHD. So this is with kids with ADHD. And the different kinds of physical activity programs used were really broad. There was ping pong, there was horseback riding, there was aerobics, there was more like physical activity, there was strength training, a lot of different kinds of physical activity, and a pretty similar benefit regardless of, of what the specific physical activity program was. I don't see any evidence that says yoga is better than Taekwondo, or better than rock climbing, or something like that. So my sense is for people who are thinking about,
how am I going to maximize the mental health benefit? I would think about finding physical activities where you feel you can connect with other people, you love it, you can show your competence, you, you feel a joy around, you feel a joy around doing it. You know, like with my own kids, I'm really trying to look for them to find physical activities that they enjoy. And probably for myself, the best mental health physical activity for me is to do physical activity with my own family, right? I have a two-year-old, I put him in a bike seat, I have my kids get on, we all get on a group call, they have little Apple Watches, and we go out and bike and, and talk. And so I don't think there's any, any kind of exercise that's going to give me a better mental health benefit than that.
We've got to take a quick break, but don't go anywhere. We have got lots more when we come back.
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Okay, here's a curve ball. What about professional athletes? Are they the most emotionally well-regulated people?
Well, if you look at them at baseline, athletes have a mental health or mood profile that is positive and differs from the general population. It's called the iceberg profile. So they're less depressed, less anxious, less tense. Now, having said that, we know that athletes have mental health issues just like everybody else. The strange thing here is that the type of training that competitive athletes in a lot of sports, particularly sports involving conditioning and endurance, have to do is generally associated with feeling worse. And the more they train, the worse they feel from a mood and psychological standpoint. It's almost like the price of performance.
The good thing is, is that as they train and reduce their training, most of them recover and then, once again, show these very positive profiles. The curious and unfortunate thing, though, is between 5% and 10% of those athletes don't recover psychologically and they overrespond to the training load and they show much worse mood states, including many of them will develop symptoms of clinical depression, which is a symptom of what we refer to as overtraining syndrome. Now, having said that, this is associated almost exclusively with high endurance athletes. But it, you know, it does show that increasing the dosage of exercise, there is
An optimal threshold, and if you go beyond that, you aren't going to see continual benefits. You may see negative changes.
Hmm. Okay, how does exercise stack up against other treatments for mental health conditions like talk therapy or medication?
There are not that many controlled studies where they stack exercise against, let's say, medication. There are a few. And exercise, generally in the case of depression, tends to be for moderately depressed individuals comparable, very similar benefits to those associated with medication. And in one study, they found that the benefits of exercise persisted longer. So they looked at them six months later, the individuals were still exercising, the other group was still on medication, and there was lower relapse in the case of physical activity for reasons that the researchers weren't clear about. In the case of anxiety
disorders, exercise often works, but again, limited evidence. It doesn't seem to be as effective as medication. But these are a mere, a small handful of studies that have done these carefully controlled longitudinal interventions.
So there's just, there's so many mental health disorders, and each one has its own literature and its own specific considerations. Essentially, we have, I think, maybe one study in ADHD where they compared, the physical activity was the comparison group. So I don't know how great their program was. And then the methylphenidate, which is Ritalin, was their, was their treatment. And the methylphenidate, you know, blew physical activity out of the water. So in that case, like I've taken those medications before as an ADHD kid, and it's a really forceful effect. So some of these medications are really, really strong. I'll
also offer that as a parent of kids with ADHD, I have benefited tremendously from parent training programs. So I tend to think of physical activity as an adjunct or something to augment those traditional services. And it's really, really important in a couple of ways. One is, most folks who need services don't get them. So among kids, maybe 40% of kids who need services get them. If you're a kid in poverty, that's more like 20%. If you don't have health insurance, that's 10%. So we're talking about huge levels of unmet need. And the average time discontinuation off medication is three months. If you're a black or Latino kid getting psychosocial treatments, you're likely of just finishing your program is like 50%.
And so their physical activity can help reach those kids. And fortunately, we do have literature in the ADHD world where we see an additive benefit of the exercise above and beyond the medication. So if you're somebody who responds to medication, that's, you know, stack that exercise, use all of the arrows in your quiver. For me personally, as a kid, when I took the Ritalin, I would get tics and I would get very obsessive compulsive, you know, touching everything seven times and my eyes twitching. And I'm 13 and none of this is cool and I don't want it. I, you know, I stopped doing it. And I think that's probably the case for a lot of folks. And so I think that physical activity and nutrition and sleep are all these extra tools that we can use to help ourselves and help our friends and family.
Thank you both so much for being here. I learned so much today.
You're welcome. My pleasure.
Thank you for having us.
Dr. Eduardo Esteban Bustamante studies the link between physical activity and mental health in kids as the director of the Healthy Kids Lab at the University of Illinois Chicago. And Dr. Jack Ragland studies exercise and sports science as a professor of kinesiology at Indiana University in Bloomington.
Today's episode was produced by Shoshana Buxbaum. I'm Flora Lichtman. Thanks for listening.
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