Hydration for Runners: Everything You Need to Know

It’s difficult to gauge the exact amount of hydration runners need. Not only do different individuals have different bodily needs, but they also have different goals in mind and different climates that they deal with. So where does one begin?

There’s just so much information out there – and some of it seems complex. What’s with all that math, right? All you’re trying to do is make sure you’re healthy, safe, and able to accomplish our running goals. Right?

Well, we’ve got you covered.


Why Proper Hydration is Essential to Runners

Let’s be clear: hydration is essential to everyone, not just runners. You’ve probably heard that you should get at least 8 cups (a cup is equal to 8 fluid ounces) a day. This is the famed “8×8 rule,” and it applies to regular, nonathletic people who don’t move much and who live in modest climate conditions.

The thing is though, the science is shaky – even nonexistent – on this rule. In fact, its origin is virtually unknown. And some evidence suggests that perhaps people don’t need that much water at all. It appears that healthy people can get away with drinking water only when they’re thirsty. That’s right. Your body is naturally built to tell you when it needs hydration; and if you heed it, you’ll be just fine.

But here’s the thing: if you fail to drink enough, you may end up becoming what’s known as “mildly dehydrated.” If you’re mildly dehydrated, it means you’ve lost enough fluids to shave off about one to two percent of your body weight. This is the best-case scenario, and in this scenario, you’ll find yourself excessively tired (fatigued), suffering from headaches, and in a generally rotten mood.

Now imagine running while feeling like that.

It becomes next to impossible. To add to those inconveniences, a dehydrated runner will also experience nausea, a lack of coordination, and spasms and cramps. That runner also increases his or her chance for heat stroke or other such maladies.

Most importantly for runners, dehydration actually has a negative impact on running performance. Studies show that even if you’re mildly dehydrated, you slow down. So if your goal is to go faster, you might want to pay closer attention to your hydration needs.

Good Hydration Habits

Now let’s go over some things that are essential hydration habits for runners.

The first thing is that you should listen to your body. Drinking when you’re thirsty – as we said earlier – will help you stave off dehydration. Again, science supports this. Your body lets you know when you’re in danger of being dehydrated, so don’t ignore it!

If you’re wondering how much you should drink during a run, try to aim for around five ounces of hydration every 20 minutes. Remember, when you run, you sweat. A lot. And when you sweat, you lose fluid (and hence body weight) as well as essential electrolytes (which you can replenish by opting for energy drinks instead of water, or by using salt tablets). It’s imperative that you replenish what you lose to ensure that your body has the fuel it needs to keep going.

Now, if you’re running fast – and by fast we mean anything faster than a mile every eight minutes – you’ll want to up your hydration intake by a couple of ounces. So instead of five ounces every 20 minutes, aim for around seven.

Here’s another quick tip that’s perhaps a bit more nuanced: you should aim to replenish each point of body weight lost during a run with somewhere between 16 to 24 ounces of fluid. That’s the recommendation of the American College of Sports Medicine. And how would you know how many pounds you lose immediately after a run? Simple – just weigh yourself! Do that before and after and then just multiply the difference with a number within the recommended range. And voila! You should be set.

Also, you should remember to drink pre-run as well. So about 30 minutes before a run, make sure to consume about 8 ounces (one cup) of water. Then follow the above advice and keep yourself hydrated during the run as well.

Signs of Dehydration

Everyone’s needs are different. You may require more or less than your running buddy. The causes of this are varied. Your body weight, climate tolerance, the rate at which you lose fluid during exercise – all of these play a role.

So in addition to following the above advice, it would be wise for you to become familiar with the signs of dehydration. That way you can recognize them as they’re happening and take steps to prevent them. The signs are as follows:

  • Thirst (obviously)
  • Excessive sluggishness or fatigue
  • Dry mouth
  • Cramps or spasms
  • Headaches
  • Nausea

If you feel any of these, try upping your fluid intake. If that doesn’t work, be sure to consult your doctor because something else may be at play.

Check out this video below for more information on how to spot dehydration on your run.

Hydration Habits to Avoid

One thing some people do too much is they drink too much. Don’t be one of those people. It’s true that too little water can cause dehydration, but it’s equally true that too much water can cause what’s known as hyponatremia – that occurs when fluid retention is so high that salt levels in your blood drop to dangerous levels. Don’t get hyponatremia. It’s not good for anyone, runner or not.

Another thing is that some people think that drinking a lot before a run somehow gives them license to drink less during that run. Don’t fall for that trap. What you should be doing is “topping off” before a run and then continuing to do so during it. Your body is an efficient machine. If you try to overfill it, it will get rid of the excess. Give it just enough and it’ll work optimally.

This one might not be popular, but for optimal hydration, avoid alcohol at all costs. Of course, a cocktail here and there won’t hurt, and we’re not telling you not to enjoy life’s simple pleasures. But alcohol does have its drawbacks if consumed improperly – check out our article on it here for more information.

Lastly, don’t neglect your daily hydration needs. In other words, don’t only drink when you exercise. Keep yourself replenished throughout the day, even on days that you don’t exercise. And while that sounds obvious, it’s something that people tend to overlook.

Final Thoughts

Did you know that fluids are not the only sources of hydration?

Solid foods, too, offer people hydration. And it’s also part of the reason why runners should pay close attention to what they eat (it matters! Check out our articles on what to eat before a run and what to eat after a run). Fruits, veggies, eggs, meat, and fish are all relatively high in water content. In fact, it’s estimated that 20 to 30 percent of the hydration needs of the average nonathletic person is derived from solid food sources.

But for runners, here’s yet another helpful tip. Coffee, contrary to popular belief, is also hydrating. Not only that, but studies show that drinking coffee (or consuming caffeine) before a run can actually help boost performance. So you can give that a try as well.

Another tip for runners (though you probably already know it): sports drinks rich in electrolytes are like a two-in-one concoction. But you can opt for water and salt tablets (or foods rich in electrolytes) instead if you don’t like the taste, the look, or the cost of sports drinks.

And that’s about it – everything you need to know about hydration for runners.

Questions? Comments? Be sure to leave them in the comments below.


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