Hydration for Athletes with Alaine Mills, MS, RD, LD

There's a science behind how to stay hydrated during physical activity, and it isn't always as simple as drinking water when you feel thirsty. In this episode, Alaine Mills, MS, RD, LD, shares insights on how athletes keep their bodies hydrated, and how you can maintain a healthy optimal hydration. She is an MUSC Health registered dietitian and certified specialist in sports dietetics at the MUSC Health and Wellness Institute.

"The number one cause of fatigue during training, during games, during sport is dehydration. [Hydration] helps to lower your heart rate during training so you can perform at a higher level. It helps your endurance. It helps your muscular strength, and it helps keep your body cool during exercise."
– Alaine Mills, MS, RD, LD

Topics Covered in This Show

• Being properly hydrated is crucial to optimal performance during any sport activity. It helps to lower your heart rate, helps your endurance, helps build muscular strength, and helps keep your body cool during exercise.
• Electrolytes are central to good hydration. We naturally lose sodium and chloride when we sweat, and without replacing this sodium and chloride, it's harder to stay hydrated.
• While sports drinks that have these additional ingredients, including carbohydrates for energy, are helpful, they are really only necessary for athletes. Because of higher calorie content, sports drinks can cause weight gain or high blood pressure for those who are not engaging in regular physical activity.
• How much fluid you should consume depends on individual weight, and consulting with a dietician is recommended. However, a good rule of thumb is to weigh yourself before and after training to estimate how much water weight you lose through sweat. Then you can rehydrate with 16 to 24 ounces per pound that you lose.
• Environment plays a key role in impacting our hydration levels. In addition to high temperatures, humidity makes us sweat more. Staying hydrated in the pool can be especially tricky because it's not immediately clear that we're sweating. Even being in the cold can cause fluid loss because of additional fluid particles lost from increased breathing.
• It's not only good to hydrate both during and after exercising, but before exercising as well. Ideally, a few hours before you start exercising, you should drink 16 to 20 ounces of cold water or a sports drink, and then an additional 8 to 12 more ounces 15 to 30 minutes before you start.
• Measuring proper hydration by thirst level is not a reliable method for evaluating hydration level. It will inevitably lead to dehydration.
• Symptoms of dehydration include decreased performance, fatigue, higher heart rate, exercise intolerance, and in worse cases, headache, dry mouth, and nausea. More severe cases can put an individual at risk of heat stroke.
• Children overheat faster than adults, so it's important for adults to pay special attention to regular hydration schedules for these younger individuals.

Read the Transcript

[00:00:00] Erin Spain, MS: There's a science behind how to stay hydrated during physical activity, and it isn't always as simple as drinking water when you feel thirsty. Today's guest, Alaine Mills, joins me with insights on how athletes keep their bodies hydrated, and how you can maintain a healthy optimal hydration. She is an MUSC Health registered dietitian and certified specialist in sports dietetics at the MUSC Health and Wellness Institute. Welcome to the show, Alaine.

[00:00:28] Alaine Mills, RD: Thank you so much for having me.

[00:00:30] Erin Spain, MS: You were on this podcast before talking about gut health, and I encourage everyone to go back and listen to this episode. It was absolutely fascinating. But today we are here to talk about hydration, especially hydration for athletes. And we hear a lot about staying hydrated. There are a ton of products out there focused on hydration, especially for athletes. So can you kick us off today by sharing the role that proper hydration plays in the performance of athletes?

[00:00:59] Alaine Mills, RD: Sure. Being properly hydrated is the number one important thing to have optimal performance during sport, during activity, no matter what your sport or activity is. So the number one cause of fatigue during training, during games, during sport is going to be dehydration. So it helps to lower your heart rate during training so you can perform at a higher level. It helps your endurance. It helps your muscular strength, and it helps keep your body cool during exercise. So all those things can help you perform your best.

[00:01:27] Erin Spain, MS: And we aren't just talking about drinking plain water. Athletes need a balance of fluids and electrolytes for optimal hydration. Just explain this balance to me.

[00:01:37] Alaine Mills, RD: So in order to stay hydrated, we need both fluid and electrolytes. And the main electrolytes that we actually need to rehydrate with are sodium and chloride, which is what's in salts. And the reason is, those are the two main electrolytes that we lose in sweat. So when we're sweating and we're losing that fluid, we're also losing sodium and chloride. And so without replacing that sodium and chloride, we can't get properly rehydrated. So it's very important to rehydrate with that as well.

[00:02:03] Erin Spain, MS: So is there a rule of thumb on how much fluid and electrolytes athletes should be consuming on a daily basis?

[00:02:11] Alaine Mills, RD: It's very complicated, and it's very dependent on the person, the environment, which I know we're going to talk a little bit more about, but one rule of thumb that you can remember, is that you should weigh yourself before training or your activity and then weigh yourself afterwards and see how much weight you lose. And then you can rehydrate with 16 to 24 ounces per pound that you lose. And if you're losing more than 1 to 2% of your body weight from the beginning to the end, then that means that you're not properly hydrating before and during activity.

[00:02:42] Erin Spain, MS: You mentioned environment, so let's talk about that. How does environment play a role, like the temperature that you're exercising in, or if you're in a swimming pool, for example?

[00:02:53] Alaine Mills, RD: So the hotter it is, of course, the more we can sweat. Also, the humidity can affect our hydration. It can make it harder for us to cool down and it can make us sweat more. Even being in the cold can actually make us lose more fluid because we're breathing a lot more and we're actually losing a lot more fluid particles from that breath, the increased breathing that we're making in the cold. And in the pool, it's interesting because we could be sweating just as much as we are when we're not in the pool, but we're not getting as thirsty and we're not seeing that sweat. So you can be at more of a risk of dehydration in the pool as well. And there's not that evaporation that's helping us cool down. So that can definitely play an effect as well.

[00:03:31] Erin Spain, MS: So let's talk about some perfect scenarios of what we can do before, during, and after physical activity to really tune in our hydration.

[00:03:41] Alaine Mills, RD: So you want to start activity really well-hydrated and that's going to be the best thing. So ideally a few hours before you start exercising, you would have 16 to 20 ounces of cold water or a sports drink, and then you'd have like 8 to 12 more ounces 15 to 30 minutes right before you start, and that'll help you start off very well hydrated. And then when you're training, especially if you're going to be training or exercising for more than 45 minutes to an hour, you want to be drinking up to a cup of water or a sports drink, depending on the environment and everything like that, every 15 to 30 minutes.

[00:04:19] Erin Spain, MS: So some people think, oh, I'll just drink when I'm thirsty, but you're suggesting that there can be more of a schedule that you put yourself on to remind yourself to drink.

[00:04:28] Alaine Mills, RD: Absolutely. Yeah. If you're just going by your thirst, you're probably going to end up dehydrated because the thirst mechanism, it's just not perfect. So it doesn't tell us exactly how much fluid that we need. So definitely doing it on a schedule can be very helpful. Sometimes we don't feel like drinking water, and using sports drinks can help because they're more palatable and they can kind of stimulate our thirst, but you definitely need to, especially in this heat of the summer, stick to a schedule.

[00:04:53] Erin Spain, MS: Let's talk about some of the signs of dehydration. What happens to the body when you become dehydrated during physical activity?

[00:05:01] Alaine Mills, RD: So you can have decreased performance. You start to get really tired and fatigued. Your heart rate is much higher. So you might not be able to tolerate the same level of exercise that you usually can. And then as things progress, you can start to get a headache. You can start to feel nauseous and that's when things are getting a little bit worse and you might be even at risk for a heat stroke or something like that. Dry mouth is another symptom. And then also muscle cramps can be another. A lot of times people think that potassium, like a lack of potassium, but it's actually more likely going to be dehydration or lack of electrolytes for cramping.

[00:05:32] Erin Spain, MS: I do want to talk more about sports drinks. There are so many of these on the market and some people, like you said, they enjoy drinking them. They would prefer them over water when working out. So what is the sports drinks for athletes?

[00:05:46] Alaine Mills, RD: So sports drinks for athletes are excellent and they're actually well-needed because we were talking about before, we need to replace those electrolytes that we're losing in sweat, or we actually won't become hydrated and we can actually become what's called hyponatremic. So, we need to make sure we replace those electrolytes. And so sports drinks were, you know, made for athletes or made for people that were exercising in the heat for long periods of time. And good sports drinks also contain some carbohydrate and carbohydrate helps us hydrate. And it also helps give us energy so that we don't get that fatigue and it helps us hydrate faster. So the right kind of sports drink is going to contain fluid, of course, water, but it's also going to have the right ratios of carbohydrate to give us energy. And then it's going to have sodium and chloride or salt to help rehydrate us. And some sports drinks have the right ratios and some do not.

[00:06:35] Erin Spain, MS: Can you give us any insight on what to look for on the back of the label when we're trying to pick out a sports drink?

[00:06:41] Alaine Mills, RD: Sure. Yeah. So when you're looking at a sports drink, you want to look for it to have like between 10 and 14 grams of carbohydrate per about eight ounces. And that's going to be the right ratio. And then for the sodium, some sports drinks have way too much sodium and then some have way too little. So something like Gatorade and Powerade, those are pretty standard. They have kind of the right amount of salt, unless for really, really high performing athletes, they may need a lot more than that. So looking for like 200, 240, maybe up to 300 milligrams of sodium per 16 ounces is probably a good rule of thumb to look for, but it's very individualized. So definitely talk to a sports dietician, especially if you're an athlete and they can help you a little bit more with that.

[00:07:26] Erin Spain, MS: You mentioned that sports drinks are designed for athletes. What about everyday people who maybe aren't engaging in physical activity, is this a good beverage choice for them?

[00:07:36] Alaine Mills, RD: Yeah, so for people that are not engaging in regular physical activity, especially if we're not, you know, exercising in the heat or we're exercising for really short periods of time, we really don't need a sports drink because they can be really high in salt, which can be not good for blood pressure or heart health. And also they can be high in carbohydrate or high in sugar. So that can be really helpful for us when we're exercising in the heat to keep us hydrated and, you know, can even be life saving for us. But if we're drinking that in the air conditioning when we're just relaxing, it could lead to high blood pressure and it could lead to weight gain because of the excess calories from those sports drinks.

[00:08:09] Erin Spain, MS: Now, what about other items like certain foods? There's some watery foods and veggies that you can put salt on that some people swear by. Also, drinking chocolate milk or a smoothie post- training. Can you talk about some of these other ways that people rehydrate?

[00:08:25] Alaine Mills, RD: Yeah, absolutely. So we're talking a lot about like hydrating with sports drinks and water during and right before, but really the goal would be to be hydrated all the time and all throughout the day. So eating a lot of nutritious, hydrating foods like fruits, like watermelon, for example, of course, is one that comes to mind. But any fruit like grapes or cantaloupe or even apples and vegetables too. All of those contain actually a really high water content. So those can help hydrate you. Also, of course, things like popsicles and soup and anything that's based of fluid, that's going to be hydrating you. Even something like milk or chocolate milk, it's, you know, 90, more than 95% water. So you're getting a lot of fluid from that. And chocolate milk is especially good to help with rehydrating because it does have some electrolytes, some sodium, and it also has the right amount of carbohydrate and protein to help us rehydrate quickly. So using chocolate milk can be really, really helpful for rehydration for sure.

[00:09:19] Erin Spain, MS: At the MUSC Health and Wellness Institute, you are coaching and advising folks on how to really set themselves up for peak performance. So tell me how you bring hydration into the world of the people that you are working with and how you help them plan out their proper hydration.

[00:09:37] Alaine Mills, RD: Yeah. So especially when I'm working with an athlete, but even when I'm working with just the general population, hydration is one of the first things that we talk about because it's so important. So we'll start off by talking about how much fluid they're drinking, what other types of drinks they're drinking other than water, how often they're hydrating, and then we'll kind of. I'll do some calculations to figure out, you know, the minimum amount of fluid that they'll need in the day. And then we'll kind of divvy that out and say, okay, you need 75 ounces of fluid per day minimum, and your water bottle is 24 ounces. So we know you need at least three of these per day, and we'll kind of set that goal for them. And then of course, if they're an athlete, we'll talk about their weight before and after training. And we might even have them start to log that. So we'll say, okay, you're not doing so well. You lost four or five pounds each training. So it's getting hotter. We need to start incorporating more fluid before training, more sips of water during training. And then, you know, maybe a sports drink to help your body really absorb that fluid better.

[00:10:35] Erin Spain, MS: So this is fairly personalized because there is that old adage out there, eight glasses of water a day is what everyone should aim for, but maybe that isn't exactly based in science.

[00:10:46] Alaine Mills, RD: Yeah, not quite. It's a good, I guess, average maybe, but really a minimum amount of fluid someone needs is based on their body weight, so obviously everybody has different body weights. So that eight cups isn't quite as individualized as it should be. Yeah. It might be a good place to start, but for some people that might be too much. And for some people that may be way too little.

[00:11:06] Erin Spain, MS: And how about for kids? Are there any special considerations for children who are athletes or teenagers?

[00:11:12] Alaine Mills, RD: Actually for kids, they overheat faster than we do as adults. So making sure that they're hydrated, very well-hydrated before making sure that there's cold beverages available to them, and making sure that it's something that they enjoy, making sure that it's something that might be flavored well for them so that they're more likely to drink. And you may have to do a lot more reminding them when to drink instead of, you know, putting it all on them, but having coaches and parents there to remind them and give more frequent breaks, especially the hotter it is, that can be really, really helpful.

[00:11:43] Erin Spain, MS: Can you speak generally about the benefits of hydration beyond sports performance?

[00:11:49] Alaine Mills, RD: So yeah, hydration is going to be beneficial in so many ways. It's going to help improve your energy level so it can help reduce fatigue throughout the day. It can also help with your joint lubrication. It can help with your skin. it can help you just feel better throughout the day and it can also help with appetite regulation. So if you're not drinking enough water, it can make you feel hungry more frequently than you should. So those are just some of the benefits of being adequately hydrated throughout the day.

[00:12:17] Erin Spain, MS: What do you do specifically when the weather is really warm to optimize your health and live well?

[00:12:24] Alaine Mills, RD: So when it's really warm, I get up even earlier in the morning to do my exercise because I do like to exercise outside because I think that that's best for just for my mental health. But if I wake up too late, it's way too hot and you know, I can't get the exercise done that I want to do. So I wake up early and I exercise outside before the sun comes up. That's what I do in the summertime.

[00:12:44] Erin Spain, MS: Well, thank you so much, Alaine Mills, for coming on the show and for sharing this information about hydration.

[00:12:49] Alaine Mills, RD: Thank you for having me.