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It’s well known that exercise is an important way to keep your heart healthy. But how does this apply to children? Pediatric cardiologist Kenneth Zahka, MD, talks about the importance of exercise throughout childhood and how activity is a part of a child’s heart health.

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Exercise and Heart Health in Children with Dr. Kenneth Zahka

Podcast Transcript

Intro:
There's so much health advice out there, lots of different voices and opinions. But who can you trust? Trust the experts, the world's brightest medical minds, our very own Cleveland Clinic experts. We ask them tough intimate health questions so you get the answers you need. This is the Health Essentials podcast brought to you by Cleveland Clinic and Cleveland Clinic Children's. This podcast is for informational purposes only and is not intended to replace the advice of your own physician.

Molly Shrodes:
Hi and thanks for joining us for this episode of the Health Essentials podcast. My name is Molly Shrodes and I'll be your host. For many people, heart health is not something they think about early in life. It comes up when you're trying to lower blood pressure numbers or start a new healthy diet, but it really should be something we continue to think about throughout our entire lives. Today. We're going to be talking about the role of exercise in a child's heart health with Pediatric Cardiologist, Dr. Kenneth Zahka. Thank you so much for being here with us today.

Dr. Kenneth Zahka:
Wonderful to join you, Molly.

Molly Shrodes:
Now, starting off. Can you tell us the type of patients you typically see and what brings them through your door?

Dr. Kenneth Zahka:
Well, I think what we should begin with is the type of patients our entire team sees because pediatric cardiology is actually a very distinctive specialty and it allows us to look at the kinds of health problems with regard to the heart that children can encounter. These can be anywhere from a fetus before birth, through childhood, into young adulthood. Especially important for many families is the evaluation of teenagers who are participating in sports, and how do we help reassure families that their young people will be healthy, active, and not have problems during their sports participation? So we see a whole spectrum of problems, but one important one is how do you know that it's going to be fine for your teenager to do sports?

Molly Shrodes:
Great. Absolutely. Now I want to start with something very general here. Can you tell me what it means to have a healthy heart?

Dr. Kenneth Zahka:
So a healthy heart is something that has both genetic and environmental basis, right? So some of us are fortunate to be born with a normal heart with all the normal heart muscle, all the normal heart valves, and be able to have that heart work well without even thinking about it for decades and decades. Some of that's largely genetically determined. Then superimposed on that is the role of our environment. I think we all know that video games and fast food are not necessarily the foundation of long-term heart health. If we step back and say, "Well, what do we even mean by heart health?" That is for the heart to be able to deliver for us what it needs to do to have us have a normal, healthy, active life. That's actually probably a little bit more complicated than a lot of us kind of take for granted. We do have a role in helping determine how well the heart we have is prepped for the future.

Molly Shrodes:
Absolutely. Now I'm wondering what are a few signs that a child's heart is working really well and is kind of set up for this success later on?

Dr. Kenneth Zahka:
So children are actually pretty good at telling us or showing us that their heart is working well. For example, if you're a tiny baby, what kind of exercise does a tiny baby do? Well, most tiny babies eat and cry, right? So exercise for that kind of age, one, two, three, four months, would be well, how, how are you feeding? Right? So feeding for them is the same as running 600 yards. So if you look at your baby and they go gobble, gobble, gobble down their milk, either breastfeeding or bottle feeding, and they breathe easily and they look great, that's a pretty good sign that the heart is pushing around enough blood, that the feeding goes well. If they cry and cry and cry and cry, another thing that requires a lot of energy and a lot of good blood flow to be going around, and they still look good, even though you feel terrible at the end of all that crying, then, yeah, their heart is likely meeting the needs.

So that's how we kind of approach the very young, the babies. Then as they get to toddlerhood and the one, twos, and threes when they start getting into trouble, some of the parents can notice when they're playing that they get a little bit out of breath or they stop and they just don't seem to keep up very well. Right? So that's an important kind of sign. Keep in mind, you have to have a lot of heart problems going on for you to really recognize any of those limitations. The heart is a beautiful organ and can make up for a lot of its own limitations. Since there's also a lot of variability from child to child and family to family, you may not actually easily detect any kind of problem. But if your child's not keeping up [inaudible 00:06:57], or it seems to be changing, that might raise a question that should be followed up on.

Then as you move forward into the years when the kids really are beginning to do sports, more so than I was watching my three-year-old grandson plays soccer when we went to visit him, that's not really sport yet. I mean, they're kind of running around and having fun, but nobody's actually pushing themselves. But you know, around age seven, eight or nine, people actually do want to perform and they'll begin to push themselves, and they may have trouble with breathing or chest pain with activity.

I also want to reassure people at this point that just because your child complains about chest pain or shortness of breath or trouble breathing with exercise, if you take a hundred ten year olds who complain about chest pain, trouble breathing, or their heart pounding with exercise, only one or two or 3% of those people are having actual heart problems, or for that matter, lung problems. It is amazing how once the kids want to compete, how they can push themselves and get to their own personal limit and misinterpret that kind of chest pounding and hard breathing that is a normal phenomenon if you really push yourself for a problem. But with that said, there are a couple of percentage where, and that's what our job is to figure out maybe what our job is as parents and maybe as grandparents, but certainly as pediatric cardiologists, oh, wait a minute, is this that 2% or 3% where it's really more of a problem?

Molly Shrodes:
So I think that's really interesting, the point you bring up about how exercise changes with each age group. That's kind of fascinating. I hadn't really thought about that, particularly with babies versus older kids.

Dr. Kenneth Zahka:
We have to think about what our bodies need to do at every single age and make sure that people also learn how to listen to their bodies. You know, when we're trying to counsel teenagers in particular about smart exercise, you start by telling them everybody should stay well-hydrated. Well, we understand that. Everybody should have good nutrition. I think most people understand that, but maybe don't always adhere to that but for sports. Then we tell them that nobody can run a marathon without working up to running a marathon, and gradual conditioning is a really important step towards sports participation, that you can't expect that you're going to run a marathon without working on it. But I think that the most important information that we can give people is the importance of listening to their body.

What we like to tell them is if you don't feel well, maybe you have the flu, maybe you have COVID, you don't actually know, but if you don't feel well, it's probably not a good day to go and exercise because your body is telling you something. Similarly, if you start off and you feel well, but during exercise, if you develop chest pain, if you think your heart is beating way too fast, if you think you're breathing way too hard, your body is actually telling you something. It's telling you you're pushing yourself too hard. A lot of what we then have to do is help people understand, this gets back to the 1% or 0.1%, is that all it is? Or is it in fact something more important than just meeting your own limits and you're trying to exceed what your current ability is? Or is it in fact some problem with the heart muscle? Is it some problem with the heart valves? Is it some problem with the coronary arteries and all the other things that sometimes can get student athletes into a difficulty?

Molly Shrodes:
Absolutely. So diving a little deeper into the relationship itself between the heart and exercise, can you explain how that works together and how exercise and the heart work as one?

Dr. Kenneth Zahka:
I would love to. So first of all, why do we have a heart? Right? I mean, the heart is a pump and it pumps blood. Why do we need blood? Well, because blood has oxygen and it has nutrients in it, and the heart is designed to pump blood around to all of our tissues. All of our tissues include our brain, our kidneys, our liver, our intestines, and they're all part of how important it is that we can think, we can eat, and all those other things. But it also pumps all the blood to our muscles. The muscles are what most sports require. So you need, in order to move your muscle, good blood flow to the muscle because that blood flow has nutrients and oxygen, and the oxygen and the nutrients combine and those muscles do the work.

With any kind of sport, and there are differences between various sports, but with any kind of sport, the amount of work that needs to be done, and the type of work that needs to be done can vary, but it requires the heart to be able to kick it up and send more blood flow to those muscles. The body is actually pretty smart. It knows how to send blood flow to the muscles and maybe not send blood flow to other places, prioritize where the blood flow goes, and the heart is pretty smart in that it can pump more blood with every beat, but it can also pump faster. So if you pump faster and there's more blood flow in every beat, then you get more blood flow to the muscles.

If you want to compare a five year old to a 50 year old, well, the amount of blood flow that they actually need to pump in a five year old is less because they're smaller, right? The heart pump works at a little bit of a different way because heart rates in children are naturally faster than they are in adults. So you start off at a faster heart rate and you can go to a much faster heart rate when you're five or 10 than you do at 50 or 60. So the normal resting heart rate for a five or 10 year old might be 70 or 80, where it would be 50 or 60 for an adult. The normal peak heart rate for a five to ten year old would be 195, whereas for a 50 to 60 year old, they may be lucky if they get to 150 or 160. That's all part of the body's adaptation to aging.

We do occasionally have parents who say, "Oh my God, my child's heart rate on their Apple watch went to 190," and we say, "Yes, that's correct." I mean, that's the heart responding in an appropriate way. So yeah, that's one way of kind of thinking about how the heart adapts to exercise.

Molly Shrodes:
Now speaking of the different types of exercise, can you explain the different types and if there is a best one for strengthening your heart?

Dr. Kenneth Zahka:
It's probably both, all of the above. So generally you can break exercise down into aerobic exercise where your body uses a lot of oxygen and the muscles are very, very active, and that includes running, swimming, biking. Then there are exercises that primarily use strength where you use less oxygen, but you still need to be able to produce greater muscle strength. So the examples of that would be weight training, right, either free weights or circuit rates. If you then think about it, when the kids come in and say, "Oh, I'm doing track." Well, wait a minute. What kind of track are you doing? Are you doing field actually? Are you the shot put or the discus person, which is primarily a strength activity?

I was reassured the other day that they don't do javelin in high school. Because one of my patients came in and he said he was a discus thrower. I said, "Does the discus ever go in the wrong direction?" He said, "Absolutely." Never want to be on a field with a teenage discus thrower because yeah, sometimes it doesn't go in the right direction. The shot put does usually go in the right direction. But then you say, well, what kind of track are you doing? Are you doing a hundred meter, 200 meters, or actually are you doing 800 meters or a thousand meters? Oh, are you a cross-country runner? You can make the same case for swimming, by the way. I mean, are you a 50 meter swimmer or a hundred meter swimmer, or are you a 800 meter swimmer? Right? It takes different muscle strengths and different types of training to do each one.

So I personally believe it's really hard to take a sprinter and make them a cross-country runner, and it's actually hard to make a cross-country runner a sprinter. I think there are people who have kind of a natural either body type or muscle type that it really allows them to do both things, but not do both things, but rather do one better than the other. So cross-country is different than sprinting and sprinting is different than strength training. The combination of some cardio and some strength is really the best, for example, for weight control and also for overall conditioning.

For the people that are simply interested in doing cardio, what we also recommend to them is that they do interval training rather than kind of steady state activity. You can get your best cardiovascular improvement by doing interval training where you take your heart rate and go from, let's say 120 to 180 and hold it there and come down and then cycle back again. If you're able to do that kind of training, you can improve your ability to exercise over baseline by about 25%. It's striking how much extra work you can train your body to do with careful conditioning.

Molly Shrodes:
That's really interesting. I was wondering, is it probably safe to say that we shouldn't be encouraging children to have a mixture of endurance and aerobic?

Dr. Kenneth Zahka:
What we want to do if children are children is for them to have fun, right? Sometimes I wonder whether we as parents kind of want to tell our kids what to do rather than either guide them or listen to what they're telling us and facilitate that. I was recently visiting my three year old grandson in New York and his parents were on a getaway weekend. I was assigned, while my wife took care of our granddaughter, to take him to soccer. He absolutely refused to go to soccer. I had to carry him to the car kicking and screaming. As I did all this, I said, this doesn't feel right to me as a pediatric cardiologist. Basically he just wasn't enjoying soccer. Right? I wasn't doing a good job of listening to what he was telling me. As soon as soccer practice was over, he was thrilled and he started playing with all of his friends, and he was the wonderful Noah I love dearly.

Sometimes I wonder whether we as parents and perhaps grandparents don't actually listen to our kids enough about, well, what are you really enjoying and what are you trying to get out of this sport? I think that that's an important thing to keep in mind, that the kids especially should be in some control over the sports that they do, and they should enjoy what they're doing and understand why they're doing it. It shouldn't be because we as parents or grandparents tell them to do it.

Molly Shrodes:
Right. Now on the topic of having joy and fun in movement, where is playtime, active playtime, fit into all of this? Does that count as exercise?

Dr. Kenneth Zahka:
I certainly hope so because it certainly helps in the making all of us feel better, right? The parents who struggle with the most active part of their children's bodies are their thumbs on the device controller. I do struggle with is that a good idea from a heart health standpoint, right? It is better to have activity. It's better for weight, it's better for blood pressure, it's better for cholesterol, maybe not in a five year old, but certainly in a five year old or a ten year old that lays the seeds for what the future is and how you can modify your own personal genetic risk. If in fact you develop a sedentary lifestyle, the likelihood of you making your genetic baseline, blood pressure and cholesterol and all the other long-term health problems that we develop as adults worse, is in fact greater.

So some form of activity, walking the dog, doing your chores, doing other things, is in fact important. But all active play, so if you have a four year old and you set up a little gym set in the backyard, and they're running up the stairs, down the slide, running up the stairs, down the slide, that's fabulous because that teaches them the joy of that kind of activity.

Molly Shrodes:
Wonderful. So I'm wondering, we talked about this a little bit earlier about how exercise can kind of morph with your age, but is there an age that parents should really start making a conscious effort to encouraging their child to exercise?

Dr. Kenneth Zahka:
So the first thing parents can do is they can certainly model activity and exercise. I think that that's a great way to help your children also enjoy being active and exercising. I don't think it's fair as parents if we hold our kids to a higher standard than we hold ourselves in terms of activity and exercise. There are certainly things that perhaps we can do together as families that can bring physical exercise and activity that everyone can do. But I mean, I don't think there's really any age where there should be any limitation placed except that for safety, right? I mean, you don't want somebody climbing up a ladder who's going to get dizzy and fall down the ladder. I mean, you have to have some common sense. No child should swim unobserved. I mean, there is some key kind of things. I mean, certainly water play is something that most young children benefit from especially if they can learn how to swim. It can be an enormous safety factor for them as they get older as well.

Molly Shrodes:
Now do the rules around kind of just general exercise safety ever change if a child's born with a congenital heart defect?

Dr. Kenneth Zahka:
You ask some of the best questions. Yeah. So I would say a significant majority of congenital heart defects require no restriction. That's because there's an incredible variety of heart defects, many of whom are mild, which don't require any limitation at all. Then there's a small group of people who have important limitations that they do need to recognize, and we need to recognize, and before they do sports, we will often, for example, do exercise testing on them to try to get a sense for what their limits are, almost to design an exercise prescription for them where you can follow your heart rate and you can do this type of activity.

Then there are a group of young people who have the most complex heart disease where their gym participation and their sports participation should really be focused on how can they be with their friends? How can they participate yet still keep them safe? What we try to do is have some kind of adaptive physical education so they learn things like coordination and balance and shooting hoops, as opposed to simply running up down the field on the basketball court, which they may not be able to do in a sustained manner.

It doesn't necessarily mean that they shouldn't do it, but they do need to be able to listen to their body and modify how hard they're exercising to match what their body can deliver. I think that that's an important message for the individuals [inaudible 00:30:35] heart disease. The extent of the restrictions on young people with heart issues is an ongoing evaluation process. I would say 10 years ago, we were more restrictive than we are today, but we still have to be mindful of if you don't listen to your body, you can push yourself too hard. There are occasional people where even if you do listen to your body, you can get into trouble and get dizzy and pass out. You have to be careful about that as well.

Molly Shrodes:
I wanted to talk to you a little bit about children pushing themselves too hard. You know, we're about to enter the fall sports season and back to school, and I'm sure a lot of children want to sign up for activities and sports and all of those fun things to do with their friends. What are some signs that they're pushing too hard and what should parents be aware of?

Dr. Kenneth Zahka:
Yeah. So this is a challenge. I will say that this is on every single parent's mind as their young person go into sports. Will that child, teenager, be the one in a million who collapses on the football field? Many of the parents are unable to kind of articulate that as their concern, but that certainly is an important concern for many parents. The usual approach to this is, remember a lot of the people who collapse on the football field, and it's really only a hundred people across the United States a year, it's a relatively small number, they have something in their family history that could be a clue. So if you look at all the sports participation forms, it's pretty heavy on anybody in your family have any problems, right? Because that abnormal heart muscle is a genetic problem, cardiomyopathy. So individuals in your family with abnormal heart muscle is really an important feature.

Then how about your personal history? Have you ever actually been sick, had some inflammation of your heart? Have you had other known problems including do you know you have congenital heart disease? That can be important. But it really always comes down to do you have symptoms with exercise? It's those symptoms with exercise that are really key to knowing whether there's going to be a dangerous situation or not. I want to go in two directions from here. One is, if somebody has, for example, an abnormal coronary artery that feeds their heart muscle, that can in fact be an important risk factor for problem with exercise. But the interesting thing is if I think over all the kids that I've seen over the last 40 years with chest pain with exercise, the story that they tell, if they have a coronary artery abnormality, is quite a distinctive one.

It's, "I do find until peak exercise. I get chest pain, maybe not with a lot of extra hard breathing, and then it goes away over the next five minutes." Those are the one in 1000 and one in 500 that we go, "You're different. We're going to really nail this down." Okay?0 Whereas everyone else who has that kind of symptom, we will do a very thoughtful and thorough workup, but we'll know where to stop because they seem like normal symptom. So sometimes just the description to a sports cardiologist like myself or my colleague, Dr. [Hammet 00:35:20], can be a good indicator of what the actual symptoms are. But the other flip side of it is if you look at everybody who has trouble during exercise, some of it is environmental, right? So we're somewhat fortunate that we're not in Texas, here in Cleveland, but when you think about it, the two a days in football, in Texas, in the heat, trying to stay hydrated, the chances of having heatstroke and dehydration is much, much higher.

So having an environment where people really do pay attention to good hydration, good nutrition, and the impact of heat, is I think key to having people not get into trouble as well. You know, there's actually a Wikipedia page about all the soccer players, the European football players, who have unfortunately died as part of sport. It's amazing what the variety of issues are. People have been struck by lightning. People have had head injuries. So I mean, there's a lot of things that can happen and somehow we accept those risks, and some of it is preventable and some of it isn't preventable. But fortunately, when you actually look at the data, I think the risk of sports participation at the high school and at the college level and certainly at the middle school level, is in fact really quite low if you take appropriate thoughtful precautions. I like the pre-participation screening. I like the concept of hydration, good nutrition, good heat awareness, gradual conditioning. I like the idea of people saying, "My body doesn't feel right. I should not try to push through this."

I think kids would do fine with that. I will also say the huge benefit that's come over the last 10 years is the deployment of automatic external defibrillators in so many different venues and sports vendors. We have actually seen the benefit of that certainly at the high school level where, even after good screening, you have an event and people are there. People know CPR. People know how to use the AED. I mean, a lot of us feel that CPR training is one of the most important things you can learn in high school because you can save a life as opposed to realizing that you didn't know what to do. It's quite a different feeling at the end of the day if you save your best friend's life or you have to look at them and know you didn't know what to do. That's why CPR and AED is so important for adding that extra level of safety for high school sports.

Molly Shrodes:
Now, I want to ask really quickly about the importance of rest. When we're talking about exercise. I feel like that's the flip side of the coin here is saying with all of that exercise and exertion, there's also recovery time. How is that important?

Dr. Kenneth Zahka:
There's a couple of different ways to approach this. So let's just take a look at what you mean by rest? In other words, most teenagers don't exactly have normal sleep patterns. What my daughter the psychologist would say is abnormal sleep and stress are not good for your body. It's not good for how you feel. It's not good for the regulation of your heart rate and blood pressure. Even such things as taking your cell phone to bed and having that be part of your bedtime or your waking time in the morning is not a good idea. So if you're trying to have your body stay in the very best tune, in terms of heart rate and blood pressure, then having normal sleep patterns, consistent time at night, consistent time in the morning, and not sleeping until one o'clock in the afternoon on the weekends, and not taking your phone to bed, and not checking social media night, is all very important. So that's one aspect of rest which I think sometimes is overlooked.

The other thing you bring up is, for example, if you do strength training, usually if you're going to strength train every day, you should do different muscle groups on alternate days, or you should limit your strength training to three times a week. Okay? That allows the muscle to recover. That I think is also important. It's also important if you're kind of an aerobic workout athlete to make sure you get enough protein after your sports activity. That's an important part of your body recovery as well.

One of the other things I like to tell people about as they think about how long it takes for their body to recover from a particular cardio workout is just look at your heart rate, right? So if your resting heart rate is 70, and you have a beautiful, let's say one hour workout where your average heart rate was 150 and you feel great and everything else, the recovery from that workout could be an hour or two. You can actually know when your body is back down to its baseline state by looking at your heart rate because the heart rate recovery will be initially relatively quick, but then it will be very plateaued for the next hour or two until you come back to your baseline. Some of that can be impacted by hydration. Some of that can be impacted by heat loading. But the heart rate is also a fairly sensitive indicator of how your body also recovers as well.

Molly Shrodes:
That's awesome. Now as we wrap up today, I just want to talk for a second about when you can't necessarily get the kids to go out and be active. A lot of kids want to be active. They want to run around as much as possible, but when there's days where they want to have a movie marathon or play the most popular video game for hours on end, what kinds of things should parents be saying to their kids to talk about the relationship between their health and their heart and exercise?

Dr. Kenneth Zahka:
This has been a huge problem during COVID, right. I think we all have learned during COVID that electronics are addictive. So I don't want to keep on bringing up my grandson, but he had actually never really had any screen time until COVID. He didn't even know what screen time was. Then his parents had to both work from home and, all right, now what do we do with Noah? So he started getting more and more screen time. I mean, he's a very active three and a half year old, but it does something to their brain. I think if you talk to most adults who are honest with themselves, they'll also agree with you that screen time is really addictive.

So it's better not to get addicted to it from the beginning, but the bottom line is that I think we as parents also have to suit up and you can't be on your phone and tell your kids not to be on their phone. If you want a four year old to be active, unfortunately it probably means that you have to be active with them. Now as they get older, then they can be much more independent. But I bet, and I'm not a child psychologist even though my daughter is a child psychologist, you know what I think you have to start young and develop those kind of patterns. It's the same thing you could say for diet and sleep and everything else.

The sports medicine people taught me something about what they tell the professional baseball pitchers about how they use their phone. Because what they found is that the pitchers would be complaining about neck pain and back pain and chest pains because they spent all their time doing this, down like that. So they make the pitchers and all the other baseball players hold their phone up like this if you're going to be using your phone. First of all, it makes it much less comfortable, but it also gives you less in the musculoskeletal problems that you'll get if you're all hunched over. So when I talk to people about going into healthcare as a profession, I actually routinely tell them make sure you learn how to type. Because even in medicine, we have so much screen time, that's such an integral part of how we do things. So I think that's something that we should always keep in mind. There is such a thing as too much screen time both for work and for play.

Molly Shrodes:
Fantastic. Thank you so much for taking the time to talk to us and sharing your insights, Dr. Zahka.

Dr. Kenneth Zahka:
I hope it's been helpful for you. Thank you for asking me.

Molly Shrodes:
To learn more about kids and exercise, visit ClevelandClinicChildrens.org/cardiology.

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