Why do we get growing pains?

0:20Jane: This is But Why: A Podcast for Curious Kids from Vermont Public. I'm Jane Lindholm. On this show, we take questions from curious kids just like you, and we find answers. Our bodies are always changing. Even as an adult, your body changes, but the changes are especially noticeable and fast when you're a kid. We have a doorway in my house where our family measures our height every six months or so. My height stays the same every time, but my kids have grown an inch every time we check, and a lot of kids grow three or four inches in just one year when they hit their growth spurt. But not everybody experiences these changes at the same time, so it's no surprise that a lot of you are wondering what is the deal with how we grow and why we stop. Let's talk with someone who can help demystify the business of growing.

1:12Zurisadai: My full name is Zurizadai Gonzalez Castillo. Jane: Dr. Gonzalez is a pediatric neurologist at the University of Texas Southwestern Medical Center. Zurisadai: And what that means is that I am that doctor that takes care of the brain and the nerves for kids. And you can think of the nerves as those wirings that go all over your body to help you move and send messages to your body. Jane: Neurologists like Dr. Gonzales, study the brain and the system in our body that makes sure the messages from your brain get where they need to go. That system is called the nervous system, and we should actually talk about the nervous system for just a second because it's amazing. We have this system that can carry messages between our brain and the rest of our body and growing is all about how the brain communicates with our body. Your nervous system is made up of two main parts. The first is called the central nervous system, which is your brain and your spinal cord. Dr. Gonzales says you can think of the central nervous system as the command center for your body. The other part is called the peripheral nervous system.

2:22The peripheral nervous system includes all the nerves that come off your brain and spinal cord and run through your body. These nerves are really important because they're the ones that get those signals out to faraway places like your fingertips and your toes or your eyes. Here's an example of how your nervous system works. Let's say I'm out running around playing with my friends, and at the last second, I see a puddle, and I'm about to hit it, but I don't want to get my sneakers wet so at the very last second, I quickly lift up and sail over it and jump clear of the puddle. I don't even really think about it. I mean, it happens in a flash, but Dr. Gonzales says there's a lot going on in my brain and body to make sure that I didn't get my sneakers wet.

3:06Zurisadai: Yeah, right. That that is actually pretty complex because everything starts in your brain, but that idea has to become actually a signal and go run through that neuron or cell, that worker that is gonna transmit or send that signal all the way down to your spinal cord, to those big nerves or wirings, then get into your muscle and tell your muscle that engine to move. Hey, let's jump and have fun. So it it it sounds easy, and yes, we don't think about it. But it's a very complex thing that happens inside our brain, and our peripheral nervous system, and our whole body works as a team.

3:53Yes, the the nervous system is amazing, but we wouldn't be able to do the things that we do without our heart beating and sending blood, or us breathing while our muscles move. So it is amazing. Jane: We humans are complex creatures. All right, let's get down to the business of growing. Sophie: Hi, my name is Sophie. I'm five years old. I am from Kansas City. I want to know how bodies grow. Cosmo: My name is Cosmo, and I'm four years old. I live in London, and my question is, how do you grow? I love the show.

4:35Eitan: Hi, my name is Eitan. Um, I'm 10 years old, I and I live in Israel, and this is my sister. Tal: Hello, my name is Tal. I'm six and a half, and we're curious about Eitan: How do people grow? Amelia: Hello, my name is Amelia, and I'm five years old, and I live in Tarrytown, New York. Avery: My name's Avery, and I'm four years old. Louis: My name is Louis. I am 10 years old. I'm from Kansas City. Grayson: Hello, my name is Grayson. I'm eight years old. I live in Richmond, Virginia.

5:07Maya: My name is Maya, and I'm six years old, and I'm from Berkeley, California. Nola: My name is Nola. I'm four years old. How do people grow? Zurisadai: Our bodies are very complex, and growing is actually very complex as well. And there is actually a whole team that work together to help us get bigger and grow. And I'm gonna just mention a few of these team members. One of those are what we call the hormones, and those are the chemical messengers that are circulating in our body, telling us, well, it's time to grow. We also have these cells that are the builders, right, that do a lot of this work to help us grow. Another thing that help us grow, and you will see that's why we get taller and taller are actually our bones. And then, not the less important, actually, I would think that is one of the most important members or of the team is actually our genes. Those are the instruction manual that have again all all of the recipe to tell our body how we should grow.

6:28Jane: And the genes those are the the pieces those instructions that came from your two biological parents so the two humans that created you each shared the genes, and those genes packaged together in a way that makes you unique. But that's how you got that instruction manual. Zurisadai: Right? So the genes are inside a big DNA book that is the bigger instruction manual, and just as you said, these come from our parents, and so we have two copies for each one of our genes. Then one that comes from mom, one that comes from dad, and we have one pair of these genes for each one of every single feature that you can imagine in your body, color of your eyes, your hair, how tall you're gonna be.

7:19Giovanna: Hello, my name's Giovanna. I'm seven years old, and I live in the UK. Why do we grow? Luca: Hi, my name is Luca. I am seven years old, and I live in Bryant Cliff Manor, New York. And my question is, why do we grow? Jane: Why do we need to grow? Why can't we just all be born fully grown? Zurisadai: Wow, that's a very complex and a really great question at the same time. Why don't we, when we are born, instead of being babies, as you said, we are not already grown-ups. When we start growing in the belly of our moms, right?

8:01We need certain time for each one of our organs to develop and function properly. So growth needs actually time, and needs a lot of energy that we cannot get just at once. And so that's why we start as little babies, and while time goes, we continue to grow until we reach that adult size. But we also reach those functions that we need as adults. Ellie: I'm Ellie. I'm four years old, and my question is, how tall do people grow? Jane: In the United States, the average adult male is five feet seven inches tall, or 175 centimeters, and the average adult female is five feet and three inches tall, or 161 centimeters. That's according to data published in 2025 by a government agency called the CDC, the Centers for Disease Control and Prevention. The tallest living person in the world is said to be a man named Sultan Kosen, who is eight feet three inches or 251 centimeters tall. But lots of people are way taller or way shorter than the average. There's a huge range of heights, lots of variation.

9:18Lux: Hi, my name is Lux. I am eight years old, and I am from Jacksonville, Florida. My question is: Why do some people grow taller than others? Zurisadai: Remember those genes that we were talking about, and I would say those are the biggest reason why some people are taller than others. As we said at the beginning, the genes are those little one-page instruction or recipe that has the information to tell us how tall we are gonna be, and that is gonna depend on again the information that you were passed on from your mom and your dad.

10:00Jane: If you're wondering how tall you might grow up to be, one clue is to look at how tall your biological parents are. But genetics alone isn't going to determine how tall you'll grow up to be. Your health, nutrition, sleep, and other environmental factors all contribute to your body's growth, and we each have a slightly different recipe, as Dr. Gonzales described it, that makes us who we are and how big we are. Layla: My name is Layla. I'm four years old. I live in in Petrie City, Georgia, and my question is: Why do people grow up so slowly?

10:36Zurisadai: Great question. First of all, because growing it is one very complex. It takes a lot of energy. So our amazing brain, right, is growing during this time. The same applies for our muscles, our bones, several other organs in our body. But while we do all these things, we're also learning, so we cannot use all of our energy just to make our brain and our muscle and our bones to grow. We also have to use some of that energy to learn new things and new skills that are going to be really helpful once we become adults.

11:19Jane: Hannah is wondering though... Hannah: Why do kids take a long time to grow, but other things don't? Jane: You know why? Why are there such different rates of growth in some things, not others? Zurisadai: A couple of things. One, each one of us, each human, each animal, has a different instruction manual about how fast they'll grow, and when they will stop growing, and for how long they will stop or continue to grow. But also, we go through phases where we have or we grow faster than others. So you might see that you go visit your grandparents, and they will say, "Oh, look how tall you are, and I just saw you a few months ago, and that is what we called growth spurts. So those are the times where our body might get taller, or you might look that you grow faster than others. But most of the times, growth actually is very slow and takes a lot of time to happen.

12:25Jane: You mentioned the grandparents, and it sometimes it feels funny because you might have a grandparent or a friend of your adults who comes in and says, "Oh, you're growing so quickly, and you think, "What do you mean I'm growing so quickly? I don't feel like it's very fast. But the adults seem to have a different sense of of our our time and the movement of time than we do when we're kids. Komu: Hi, my name is Komu. I'm four and a half years old, and I want to know why can we not feel our body's growing.

12:54Saya: Hi, my name is Saya. I am eight years old and live in Dallas. Why did it grow, but we don't feel it? Zurisadai: I will start with the bones, right? Because that's probably one of the the things that we might notice, and is more evident how tall we are getting while we grow, and the part of the bone that has these growing zones that are kind of squishy and allow for the bones to make new areas, so the bone continues to get bigger and larger, actually do not have nerves that help us feel, and because do not have those nerves that help us feel whenever we are growing, we do not feel that growing.

13:42Jane: And when you talk about the parts of our bones that are squishy and growing that don't have nerves, are those our growth plates? Zurisadai: Yeah, correct. Yes, those are the growth plates, or we can also call them growing zones. Right? Yes, those are the squishy areas of the long bones mainly, and those are typically at the near end of the long bones, and that's exactly where a new bone is being added by these cells or work builders, and that's how the long bones grow.

14:15Jane: And if kids, if you're interested in learning more about bones, we actually did a whole episode on what happens when you break a bone, and it can be really different depending on whether you break it in the middle or you break it near a growth plate. So go and look for our episode about broken bones if you want to learn more about the bones. And broken bones can certainly hurt, but one of the other questions that kids have asked us is, we do sometimes kind of feel ourselves growing. We might not feel that skin stretching out or that bone stretching out, but a lot of kids have had the experience of feeling just kind of pain in your legs, maybe or your knees, and having an adult or a doctor say those are growing pains.

14:56June: My name is June. I'm eight years old and live in Bellingham, Washington, and. My question is: What is a growing Eva: I'm Eva from Wisconsin, and I'm six years old. pain, and why does it hurt? Cass: My name is Cass. I'm eight years old, and I live in Jersey City. Lila: My name's Lila, and I'm five and a quarter years old. Darcy: My name is Darcy. I'm eight years old. I live in Caldwell, Idaho. Bridget: My name is Bridget. I am 10 years old. Lily: My name is Lily. I'm nine years old. I live in Raleigh, North Carolina, and my question is, why do I get growing pains?

15:35David: Why do we get growing pains, and how does it happen? Sage: My name is Sage. I'm five years old. I live in Seattle, Washington. Why do we get growing pains? Zurisadai: Well, that is an excellent question. So, even actually, though in the name, the word "growing" is present, we actually now know, and again, doctors and scientists have looked at this, and we know that the pain does not come actually from the actual growing. And then you might ask me, well, why didn't you guys change the name? Well, we have been using this name for quite a long time. That it just made sense to keep it.

16:26Jane: So what is it? Zurisadai: So I'm gonna be honest with you. The reality is that we don't really know exactly why does it hurt, but we have some ideas. We think that it hurts because it is a way your body is actually telling you after a very long day that you've done a lot of things that you need a break and you need rest and is mostly again this sensation achy sensation of your legs because you have done a lot of things. Jane: And how can you tell the difference between growing pains and other kinds of pain that you might need to see a doctor about? Well, if your pain happens in both legs and it's kind of achy, but it usually goes away by the time you get up in the morning, you're probably experiencing those things called growing pains. But if the pain is related to an injury, like University of Texas Southwestern Medical Center. We're learning maybe you twisted your ankle, or if you're seeing swelling or redness, or if it hurts badly enough that it's preventing you from doing fun things, you should definitely talk to your adults. After the break, why do we stop growing, and is it true

17:35that our ears and our noses never stop? Stay with us. all about how our bodies grow, and we have some questions from you about specific body parts. Jolene: Hi, I am Jolene, and I am six years old, and I live in Omaha, Nebraska. And my question is: Do bones grow? Ethan: My name is Ethan, and I live in Colorado. And I'm six years old. And I want to know how bones grow. Zurisadai: Yeah, I think we we touched a little bit about this earlier, we have many many bones in our body. The most important ones that will help us get taller are the long bones, like the ones on our arms, the ones on our legs, and again at the end of our long bones, we have these growing zones or growth plates that are more squishy and have these areas that will allow to make new bone, so our bones keep getting longer and longer.

18:52Hunter: Hi, my name is Hunter. I am nine and I live in Calgary, Alberta, Canada. And here is my question: Do tongues grow as we get older? Zurisadai: The tongue is a muscle, and as a muscle, again, is one of those cells that will continue to grow. While I mean, our entire life, the difference is though that again, even though the tongue right is a muscle, compared to other muscles in our body that help us move, there is also going to be a time when our face has reached right the size of an adult.

19:29Well, it wouldn't make more sense for our tongue to continue to grow because that space within our mouth wouldn't be able to hold or keep that size of our mouth. So compared to other muscles, it will you will get a time. Well, it will stop growing. Jane: Okay, so our tongue will stop growing as we, once we're adult size, because otherwise we would have too much tongue for our mouth, and we wouldn't be able to talk anymore. Poppy: Hello, my name is Poppy, and I am seven. I am from Boston, Massachusetts. I was wondering, do your eyes grow as you get older?

20:04Zurisadai: Yeah, that your your eye will continue to grow also up to that point. That again, that cavity or that area that will hold the globe, your eye, right, has reached that adult size, then it will stop growing. Jane: Okay, so if our eyes stop growing once we reach adulthood, Allegra and Eli are both wondering about our ears and our noses, which many of us have heard that those never stop growing. Allegra: Hi, my name is Allegra. I'm eight years old. I live in Orange County, California, and my question is, why do our ears and nose keep growing when our bones don't?

20:43Eli: My name is Eli. I am seven years old. I am from Franklin, Wisconsin, and my question is, why do your nose and ears never stop growing, but your eyes do the same? Zurisadai: So that is a very interesting question, and it is actually true. So our ears and our nose are mainly made out of cartilage, and is is not bone. It is slightly different. It is more squishy, and you might see and you might notice that older people, your grandparents, even though again they are already grown-ups, it seems like their ears and their nose look slightly bigger, and that is again because the cartilage does not have those growing zones that at some point will stop growing, but it doesn't continue to grow fast, right? That's why we don't have super big noses, right? You might still see some growth, right, through your entire life compared to other bones, right? That don't get taller but might get bigger. The bones, but yeah, those those are different areas of your body that will continue to grow.

22:01Jane: So it's almost like cartilage doesn't have any shut-off valve. Doesn't have anything that tells it to stop, although it does slow down. Zurisadai: That is correct. Nina: Hi, my name is Nina. I'm five years old and I live in Hopkinton, Massachusetts. Why does hair keep growing? Cameron: My name is Cameron. I'm five and a half, and I live in Ohio, Twysburg. Why do people's hair keep growing even when they cut their hair? Micah: My name is Micah. I am eight years old, and live in New Rochelle, New York. And my question is, how do your hair and toenails grow back after you cut them?

22:43Jane: Because hair does keep growing your whole life, and it can grow pretty fast. Zurisadai: That is true, and that's what we talk about. Each one of our organs have a different rate for growing. The speed, how fast does it grow? So your hair is one of those that will continue to grow, and it will be significantly faster than other parts of your body. And I will put also within that same group your fingernails and your toenails, and that's why you keep needing a haircut fairly often, and you also have to trim your fingernails and toenails.

23:23Jane: Let's talk a little bit about ways that we can help ourselves grow up and grow healthy and strong. Ellie: My name is Ellie. I am eight years old. I live in New York. Why does sleep help us grow? Zurisadai: Really good question. Sleep is very important. I agree, and there is a few things that will happen during our sleep. Remember that I said that our brain is part of that central nervous system, right? Inside our brain, there is a tiny gland that is called the pituitary gland. Now that glands make a hormone, and you might recall that I said at the beginning that growing is complex, and there are several players on this team, and one of those are the hormones, right?

24:14The growth hormone, it is actually one of those chemicals that is released from this gland onto your blood and sends the message it is time to grow, and actually this growth hormone works harder at night. So we do need a good sleep, right, to be able to grow and grow healthy. Jane: So, if you want to be really tall, you should be getting a really good night's sleep, just to give yourself any little boost you can. Zurisadai: That is correct. That's, that's one of the the reasons your parents will say, well, it is very important that you go to bed on time, that you give your body time to rest. And to grow.

25:01Zaya: My name is Zaya. I live in a van, and my question is: Why do we need to eat healthy foods to grow? Zurisadai: So there are building blocks that are needed, so our body continues to grow, and it is better when those building blocks are of good quality, right? And where do we get those building blocks? That actually comes from what we eat, and some of the big categories for these blocks include the proteins that we can get right from eggs, meat. Right, we need vegetables because we can get vitamins and minerals that are those helpers to build several systems in our body. We need healthy carbs. We need the rice, the bread to give us that energy, right, to grow.

26:04So it is very important that we get all of these blocks with good quality, so we can continue to grow. Jane: So there are lots of parts of our bodies that grow our whole lives, and other parts that stop at a certain point. But Abe and Esther from New York are among the kids wondering why any parts of our bodies stop growing at all. Milo: My name is Milo. I live in Chicago, Illinois. I'm six years old, and my question is, why do adults stop growing?

26:34Addison: My name is Addison. I'm eight years old, and I live in Greenwich, Connecticut. My question is, why do people stop growing when they become adults? Charlotte: I'm Charlotte, and I'm from Rockaway, New Jersey. And my question is, why do adults stop growing when they become grown-ups? Nora: Hi, my name is Nora. I'm six years old. I live in Rochester, New York, and my question is, why do grown-ups stop growing? Franklin: I'm Franklin. I'm five years old. I live on an island called the Isle of Wight of England. Why do plants keep on growing, but people stop growing?

27:14Zurisadai: So the main answer will be because of again each one of our body parts has a time or signal when it will either has to stop growing or has to slow the growing. Plants actually do not have growing zones, right? So there is no signal that tells the plants, well, it is time to stop growing, and so that's why they keep growing and having branches and new leaves, the entire life of the plant. But humans were not like that, right? We need to maintain the energy to function well. So when we have reached our adult size, most of the energy that was actually being used to grow, it is used to maintain our function, so we can keep again having fun, spending time with our loved ones, and learn still a lot of new things.

28:11Jane: So, what is it that we gain then from not growing anymore as adults? You know, if that energy is redirected into things other than growing, then there must be some benefit, right? Like, what's good about being an adult who's not growing anymore? Where's that energy going? Zurisadai: The energy is actually going into several things. I would say we're not growing taller, but the the energy is still being used, not just to learn, but there are other ways to grow, so the bone is not growing taller, but it's getting thicker, which is a different way to grow, right?

28:47the The muscle again was not a tiny muscle, but it continues to grow, and we talk about several other systems that are not growing in length, but are still growing, are being replaced, so we ensure that each one of our systems is still working well. Jane: I have to say too, as a parent, if I had to devote all of that energy to growing, I would be even more exhausted with all the energy that I'm supposed to give to my children instead. So maybe, yeah, our energy is redirected into other things to help the next generation grow.

29:22Zurisadai: Well, yeah, and as just as you said, as we grow, we have new responsibilities and new things that we have to do, right? That we weren't doing when we were kids, right? And some of those activities can be more complex, so we might use that energy to replace from the growing and take that for these other tasks and activities. Jane: That's it for today's episode. Thanks so much to Dr. Zurisadai Gonzalez Castillo for helping us understand how our bodies grow. As always, if you have a question about anything, have an adult record you asking it on a smartphone. You can use an app like voice memos, then have your adults email the file to questions@butwykids.org. We take questions on all kinds of topics, so whatever you're curious about, ask your adults to record you. But Why is produced by Sarah Baik, Melody Bodette, and me, Jane Lindholm at Vermont Public. We're distributed by PRX. Our video producer is Joey Palumbo, and our theme music is by Luke Reynolds. If you like our show, please have your adults help you give us a thumbs up or a review on whatever podcast platform you like to listen to. It helps

30:32other kids and families find us. And if you want to know more about But Why, you can always have your adults sign up for our newsletter. You'll find it right at buthwykids.org. We'll be back in two weeks with an all-new episode. Until then, stay curious.