Hydration and Running – What to Drink Before, During, and After Your Run

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It doesn’t matter where you run, how far you go, how fit you are, or even how cold it is outside. The biggest threat to a runner is dehydration, which can sneak up on you unexpectedly.

While mild dehydration might not cause permanent harm, it can definitely slow your progress if you’re training for a race. Especially in warm weather, it’s easy to unintentionally let dehydration become severe unless you stay mindful of how much you are drinking.

Here’s our advice on what to drink before, during, and after your run. By following these tips, you can expect better performance and overall improved health!

Why You Need to Stay Hydrated

No matter the weather, when you exercise and your core temperature rises, your body starts to sweat to cool you down. Sweating leads to fluid loss, and since your body needs fluid to stay at peak performance, not replenishing it can take a toll on your body.

When your body’s fluid levels decrease, transporting oxygen and nutrients becomes more challenging. As a result, your muscles receive less fuel than they need to perform at their usual level.

You may not notice the effects of dehydration immediately. But dehydration can sneak up on you, and it comes with initial symptoms like:

  • Headache
  • Fatigue
  • Dry mouth
  • Lightheadedness
  • Muscle cramps

If you don’t rehydrate at this point, your body will start to develop worse symptoms, and you will notice a decline in performance. Not only will your performance suffer, but if you’re constantly dehydrated, your health will also suffer.

How Much Water Is Enough?

There’s no one answer to this—it depends on many factors. It’s a good idea to hydrate before your run and rehydrate afterward. But drinking during the run is dependent on various things, including:

Sweat Rate

Everyone’s sweat rate is different. Your sweat rate is the amount of water you lose per hour of exercise. If you can calculate this, you can work out exactly how much you need to carry with you when you run.

Running without knowing your sweat rate is like driving without a fuel gauge, you won’t have any indication of what kind of fluid intake is right for you.

It’s worth calculating your sweat rate to know how much to aim to drink per run. Here’s how:

  • Weigh yourself without clothes.
  • Go for a 1-hour run.
  • Weigh yourself afterward (again without clothes).
  • Use this calculation: Post-run weight – pre-run weight = weight loss during a run.

Convert that number to ounces, and that’s how much fluid you lose during your run. In other words, that’s how much you have to drink in an hour of exercise to stay hydrated.

Pro tip: If an hour is too long, you can do a 30-minute run. Just multiply your result by 2 to get your hourly sweat rate.

We highly recommend doing a “sweat rate check” every few months. Your sweat rate can change as you get fitter and as the seasons change, so make sure you check every so often.

Length and Intensity of Your Run

The longer your run, the more water you’ll need. It doesn’t take long to start dehydrating, so you’ll want to drink often. Make sure you have enough water to last the duration of your run.

Your intensity also matters. The faster and harder you run, the sooner you’ll heat up and the more you’ll sweat. Lower-intensity runs will take longer to warm your core temperature. So you’ll need more water during a HIIT workout than during a LISS workout.

Weather Conditions

The hotter it is, the more you’ll sweat. When your core temperature is high, and it’s warm outside, there’s a much higher chance of becoming dehydrated.

Humid weather can also cause you to dehydrate faster. When the air is already moist, it’s harder for your body to cool down because sweat doesn’t evaporate easily. Keep in mind that humidity doesn’t only happen when it’s hot!

Body Weight

If you’re overweight, your body must expend more energy to move, which means it can heat up that core body temperature quickly. You’re likely to sweat more as you expend energy, whereas leaner people will likely sweat less.

What to Drink Before, During, and After Your Run

Here’s our advice for hydrating effectively at every important point for runners—before, during, or after your run.

Pre-Run Hydration

Starting your run properly hydrated can make a much bigger difference than you realize.

The key is to start drinking soon enough before your run. Don’t wait until you are about to leave and chug a glass of water. Start drinking more 2-3 hours before you head out.

What to Drink

Plain water is your best option before your run. If you want to, you can choose a sports drink, but it’s unnecessary. However, if you do go for a sports drink, choose a low-sugar, low-calorie option.

How Much Should You Drink?

If you’re planning on running for less than an hour, you can drink 16 to 20 ounces about 2 hours before you’re planning on running. If your run will go over an hour, add another 4 to 8 ounces to that total.

What Should You Avoid?

Avoid caffeine or alcohol before your run. They both dehydrate you, even if there’s water involved. So you’ll be starting your run off dehydrated.

Also, avoid drinking too close to when you’re going to run. This could lead to you needing to stop for a break and skewing all your training times.

What to Drink During a Run

The answer to this question depends on the duration of your run., although some other things do come into play. Here’s what you should know.

Less Than an Hour

It’s generally accepted that you don’t need to take water if your run is less than an hour. However, this is up to you—you will dehydrate, but not so much that it’s likely to have noticeable effects.

Of course, if it’s extremely hot, you’ll need to take water with you as you’ll be sweating more than usual. Use your discretion, and when in doubt, take water along with you.

Runs Longer Than 60 Minutes

You’ll need to hydrate for runs lasting an hour or more. Aim for 4 to 8 ounces every 15 to 20 minutes, which can be achieved by taking a few small sips every few minutes.

Like shorter runs, the heat and your intensity will affect how much fluid you need, so be mindful of this when planning how much water to take with you.

What Should You Drink?

For shorter runs, water is good. You should supplement with electrolytes for longer than an hour to keep your body’s fluid/electrolyte balance in check. You can choose a sports drink that contains electrolytes or just use an electrolyte tablet.

Post-Run Hydration

Don’t forget to rehydrate after your run. This will help to bring your fluid levels back up to normal so your body can effectively recover. Knowing your sweat rate comes in handy here because you can calculate how much water you’re likely to need to rehydrate.

What Is the Perfect Drink After a Run?

This is different for everyone, but here are some common favorites you’ll spot at races.

Water

You can’t go wrong with water! Again, you may want to consider adding an electrolyte tablet, but water is the most hydrating option.

Electrolyte-Rich Drinks

You can drink an electrolyte-rich beverage after your run to help bring your levels back to normal. It’s up to you.

Chocolate Milk as a Recovery Drink

Interestingly, some research shows that chocolate milk can be a great post-run rehydration! If you aren’t a fan of sports drinks but you love a throwback to childhood comforts, this could be something you really look forward to after a run!

How to Tell if You’re Not Getting Enough Fluids

The signs of being dehydrated are the same whether you’re running or sitting in the office, although they’re more noticeable when you’re active. If you’re experiencing any of these signs—or more than one—it’s likely that you’re dehydrated but haven’t realized it!

Feeling Thirsty

Your brain activates the “thirsty” response only after dehydrating your body. If you start to feel thirsty, it’s important to rehydrate as soon as possible to avoid some of the negative effects that come with being dehydrated.

Dry Mouth

Dry mouth occurs when the mucosal linings of the inner cheeks and jaw don’t have enough moisture, so they start to feel sticky and uncomfortable. This is usually a sign of a lack of fluid in the body, and in most cases, the first instinct is to drink something.

Dry Skin

This one is less obvious. External factors, like heat, wind, or other seasonal changes can cause dry skin. But in some cases, it comes from the inside—more specifically, there’s not enough moisture in the skin.

If you’re struggling with dry skin along with one or more of the other symptoms here, your dry skin could result from dehydration instead of external causes.

Unusual Fatigue

An unexplained lack of energy or unusual tiredness could also be a sign of not having enough fluid in your body. Every process in the body requires water to run, so when your body is constantly fighting for the little bit of water it gets in, it causes fatigue.

You might find that you don’t perform well during a run, or just that you’re tired throughout the day and feel like napping. This could simply be a result of dehydration.

Headaches

Lower fluid levels mean the blood doesn’t flow as easily. The heart has to pump harder to get it around the body, which could lead to a “blood pressure headache”—a pounding head for no apparent reason.

Dark-Colored Urine

Darker yellow means you need more fluid in your system, as the urine is not as watered down as it should be due to a lack of fluid. You should see light yellow, so use this as a daily gauge!

Tips for Staying Hydrated

Here’s how to stay hydrated, whether running or resting!

Drink Water Throughout the Day

The best way to stay hydrated is to sip on water throughout the day. Keep a bottle with you and take a few sips every 10-20 minutes. If you get into this habit, it will be much easier to maintain good hydration throughout your run.

Avoid Caffeine and Alcohol

Caffeine and alcohol are natural dehydrators that draw moisture out of your cells. While there’s nothing wrong with having one or two here or there, indulging in multiple caffeinated or alcoholic drinks daily can keep you in chronic dehydration.

Pay Attention to the Color of Your Urine

This is a good way to stay on top of your hydration levels, and it’s easy to do! Every time you go to the bathroom, double-check the color of your urine. If it’s looking a bit dark, you know you need to go and drink. If it’s light yellow, you’re probably adequately hydrated.

Watch for Signs of Dehydration

Knowing the signs and symptoms of dehydration is the first step to ensuring you’re always hydrated! Take note of what your body displays when you’re dehydrated. Be mindful of how your body is feeling.

  • Is your mouth dry?
  • Is your head starting to feel fuzzy?
  • Are you feeling more fatigued than you should be?

The moment you start feeling these things, you know it’s time to take a drink. If you can avoid dehydration before it becomes a problem, you’re much less likely to suffer negative effects.

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AUTHOR

Ben is an avid road and trail runner, and has completed multiple marathons and ultras. A former running store owner, he now shares his knowledge and experience writing these articles.