The Runner’s World Guide to Nutrition and Fueling: Hydration

You may be able to recall the delicious, carb-filled breakfast you had before your recent long run, or the protein-packed lunch you ate following a crucial speed session. But do you remember how much water and electrolytes you drank before, during, and after those runs? If you can’t remember whether you had a single glass of water during your day, you could be sabotaging your runs and performance.Hydration plays a critical role in supporting your overall health. Add running into the mix, and your hydration needs increase in order to support your mileage. In the Runner’s World Guide to Nutrition and Fueling, you’ll learn how to best meet your tailored hydration demands, add electrolytes into your fluid intake, and create a personalized hydration strategy that supports your training, racing, and daily life.What You’ll LearnIn The Runner’s World Guide to Nutrition and Fueling, we’ll teach you:How to best gauge your overall hydration needs.Why drinking water isn’t enough to stay hydrated, and the importance of adding electrolytes into your fueling plan.Key ingredients your hydration drinks should have in them, and how they aid your training.Simple strategies you can utilize for consistently hydrating throughout the day.How hydration needs change as you age.Common hydration mistakes runners make on race day, and how to avoid them.“When those longer runs come around, you’re going to need more electrolytes. You are going to need some carbohydrates. All of that goes together with your water input, and so that gives you that really nice foundation that you need hydration-wise.”—Briana Butler, registered dietitianWatch VideoGo DeeperDetermining Your Hydration NeedsOften, hydration miscues happen when runners have no idea where to begin. Maybe you don’t have a clue how much water you should drink each day, or what types of hydration products to add into your fueling routine. While hydration needs differ from runner to runner, the baseline recommendations stay the same. At a minimum, you should aim to hydrate enough to replace the fluids you lose while exercising.Start by measuring the amount of fluids you shed each time you train. You can do this by weighing yourself before and after a run to determine sweat loss, examining your urine color, or even visiting a lab for more advanced sweat testing. Once you have an idea of how much you’re sweating during training, you can get a better idea of how much water you should be drinking to replace what you expel.StaffYou can utilize the urine chart to keep tabs on your hydration levels throughout the day.According to the Institute of Medicine, men ages 19 to 50 should intake around 125 fluid ounces of water daily, while women within that age range should consume 91 ounces. That may look like consuming 16 to 20 ounces of water when you wake up in the morning, followed by consistent water intake throughout the rest of the day. You can adjust that water total based on your needs, including your sweat loss measurements. General recommendations include drinking 16 to 20 ounces of fluids per pound you lost while exercising.Struggling to consume enough water throughout the day? Try flavoring your water, keeping your water at a preferred temperature, or drinking it from a fun water bottle or cup to make drinking water more enjoyable. “I would look into adding flavor,” says registered dietitian Amy Goblirsch in the Runner’s World Guide to Nutrition and Fueling. “Can we add some lemon, some lime, can we infuse some other fruit in there to make it a little bit more exciting?”Hydrating throughout the day, and replenishing what’s lost during exercise, can help you prevent dehydration, which can significantly inhibit strong running. Even as little as 2 percent dehydration can result in a 10 percent decrease in performance, along with the onset of symptoms like muscle cramping, dizziness, and fatigue that can impact efficiency, pace, and recovery.But staying hydrated doesn’t mean constantly chugging water. There’s also such a thing as being too hydrated, and overhydration can lead to hyponatremia, a condition where your body has too much water and not enough sodium in your blood. Signs of hyponatremia include nausea, vomiting, headaches, confusion, muscle weakness, and cramps.Don’t Forget Your ElectrolytesJust drinking water isn’t enough to support healthy, efficient running performance. In order to stay properly hydrated, you should also consume fluids with electrolytes that help your body replenish minerals lost during exercise through sweat. Common electrolytes include:SodiumChloridePotassiumMagnesiumCalciumThink of electrolytes like power lines in your body. They’re positively or negatively charged ions that stabilize your fluid levels, regulate your nerve function and pH levels, and promote muscular contraction. Without them, your body won’t have enough charge to power your running, or even proper muscle and body functioning.You can find electrolytes in the form of sports drinks, powders, and tablets designed for quickly replenishing what’s shed by sweating. You’ll also get sodium and other electrolytes from foods you eat in your regular diet, including fruits, vegetables, juice, milk, and even coffee. Often, you can meet your minimum electrolyte needs through your whole-food diet, but when you’re training hard or sweating excessively, electrolyte supplementation via powders and tablets can help you stay optimally hydrated.Determining your electrolyte intake depends on your individual sweat loss. For example, a salty sweater that loses more fluids and sodium during a run will need to consume a much higher amount of electrolytes. Weighing yourself before and after a run, or completing an advanced lab sweat test, can help you identify your sweat rate—and how much sodium you may need to consume on a regular basis.It’s important to note, though, that every runner may not need aggressive electrolyte supplementation as part of their fueling regimen. If you live in a temperate location, train indoors, or run less than an hour each day, you likely won’t need as many electrolytes as a runner logging double-digit mileage each day in humid Florida weather. Other factors, including age, health, and breastfeeding, can alter your hydration needs. That’s why it’s important to evaluate your individual training demands, sweat loss, and environment to lock in your ideal electrolyte strategy.Hydration on Race DayThe key to nailing your race hydration? Practice. During your training block, you should test out different hydration strategies across varying weather conditions, times of day, and lengths of runs to find what works best for your performance. Once race day hits, you’ll want to follow an important principle: Nothing new on race day.“Testing out your sweat losses during training is a great place to start,” Briana Butler, registered dietitian and cofounder of Power Portions, explains in our Guide to Nutrition and Fueling. “Don’t start testing it in the middle of a race, right? You want to do that leading up to it. Test it in the heat, test it when it’s cooler, test it in the morning, test it in the evening time.”Before you hit the starting line, consume both water and electrolytes (e.g., 16 ounces of your go-to sports drink), ideally as part of your pre-race meal. Sip on your fluids, rather than chugging them, and have a hard drinking cutoff of two hours before start time to avoid mid-race bathroom breaks.Many races—especially marathons and half marathons—will offer water and sports drinks at various points along the route. Prior to race day, research where these hydration stations will sit on the course and what drinks they will provide. If the course doesn’t have reliable fueling stations or doesn’t offer a product you feel comfortable taking on race day, carry a hydration device like a handheld bottle filled with your preferred electrolyte mix to meet your hydration demands.Common Hydration Mistakes to Avoid on Race DayAvoiding the following hydration mistakes dietitians commonly see among racers can set you up for a better race-day experience:Trying a new hydration strategy or product on race day.Neglecting to carry hydration with you, or skipping over hydration stations.Consuming too much water and not enough electrolytes, which can lead to hyponatremia.Not taking in enough water and electrolytes to meet the race climate and conditions. (Yes, you still need to hydrate in cold temperatures!)Drinking less to avoid bathroom breaks.The bottom line: Your midrace hydration approach shouldn’t be too complicated. Practice your hydration during training, bring your fluids with you on race day (or utilize hydration stations), and make necessary alterations to take into account weather and course conditions. Sticking to what you know, and understanding your body’s hydration needs, will propel you to a strong performance on race day.Got questions about performance nutrition?Fueling can be the difference between a run that feels strong and one that falls apart.Through conversations with leading sports dietitians, nutrition experts, and coaches, the Runner’s World Guide to Nutrition and Fueling turns the science of sports nutrition into practical, runner-friendly strategies for everyday training and racing. Available exclusively to Runner’s World+ members on September 10!Ashley is Editor of Content Hype at Hearst’s Enthusiast & Wellness Group. She is a former collegiate runner at UNC Asheville where she studied mass communication. Ashley loves all things running; she has raced two marathons, plus has covered some of the sport’s top events in her career, including the Paris Olympics, U.S. Olympic Trials and multiple World Marathon Majors.