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Proper Hydration Techniques for Endurance Sports (Understanding the “Drink Before You’re Thirsty” Rule)

sweaty cyclist who is probably dehydrated

The most important aspect to sports nutrition is, without a doubt, proper hydration. Poor food choices can get you in trouble, but inadequate hydration can get you killed!

Whether it’s dehydration (too little water) or hyponatremia (too much water), you’re in trouble! Fortunately, proper hydration really isn’t that complicated. The tips I have for you here should cover everything you need to know to stay safe.

What You Should Drink

The actual beverage you choose will be based on exercise type, exercise duration, weather, and personal preference.

For low intensity exercise (perhaps hiking or a casual bike ride), stick with plain water. For higher intensity training that is a short duration (sprinting workouts under 60 minutes), I would still stick with water.

If you will be maintaining a fairly high intensity for a longer duration (a fifty mile bike ride with lots of climbing), you probably want to switch to a sports drink. That will help replenish the calories you are burning, provide necessary electrolytes, and aid absorption.

At the very least, I’d use Nuun tablets to get electrolytes. Nuun is a great choice if you hate sports drinks. (Similarly, the new Hammer Endurolytes Fizz is a fine choice.)

If you’re going to conquer something of very long duration like a 24 hour mountain bike race, I’d consider choosing a sports drink that contains carbohydrates and protein (which also means more calories to keep you energized). The two main options here are Accelerade and Hammer Perpetuem.

Don’t forget the weather. The hotter it is, the more likely I would be to use a sports drink rather than plain water for any activity over an hour in length/duration. Exercising in extreme heat can dehydrate you rather fast!

Sports drinks also come in handy in cold weather. Sports drinks have a lower freezing point than plain water, so they’ll stay liquid slightly longer when riding in frigid temps!

And of course, personal preference. You might love sports drinks and use them all the time. That’s fine (within reason). Or maybe you hate sports drinks, even light ones like Nuun. Then you could stick with plain water, but I’d recommend taking some Endurolytes or other electrolyte supplement to make sure you don’t run low on sodium.

How Much and How Often You Should Drink

During endurance exercise, I like to take a few sips of water every 15 minutes. That works out to roughly 16oz of fluid per hour.

In most situations, 16 ounces per hour will keep you hydrated without forcing you stop to pee all the time. But of course, that varies with the weather. On cool days, a 24 oz water bottle might last me for two hours. But on a hot day, I might finish 24 oz within an hour!

That guideline should give you a good starting point. However, everyone is different, so you might need to adjust your fluid intake a few times to see what works best for your body.

“Drink Before You’re Thirsty”

The old adage was always to eat before you’re hungry and drink before you’re thirsty.

There could be a variety of reasons why this saying came about. Perhaps dehydration was becoming too common.

Unfortunately, today we all know the dangers of going too far in the other direction and suffering from exercise-associated hyponatremia (essentially becoming too hydrated).

“Drink to Thirst”

The latest guideline I’ve heard is to “drink to thirst.” Or, drink whenever you’re thirsty.

Neither is very specific. And even if you do drink before you’re thirsty, that doesn’t mean you’ll drink more than someone who drinks directly according to their feelings of thirst.

The truth is, it’s probably an individual thing. I get thirsty very frequently, so if I listen to my body, I’ll drink A LOT of fluid. Other athletes rarely feel like drinking, so sometimes they may need to drink before they’re thirsty.

That’s why I preach the value of getting to know your body (and your sweat rate).

Pre-Hydrating Technique

While staying hydrated consistently works great, it’s possible to do just fine with a limited fluid intake during exercise. That’s where “pre-hydrating” comes in. In a nutshell, pre-hydrating means you drink quite a bit of water before exercise to make sure you are completely hydrated.

Here’s an example: Back before I had a Fuel Belt to carry nourishment with me, I’d go jogging for 1-2 hours without water. Sometimes I’d find a public water fountain, but other times I’d drink nothing whatsoever.

I got thirsty, but by being fully hydrated when I started, and drinking plenty afterward, I had absolutely no problem with staying hydrated. Even when exercising daily.

Obviously this strategy would be a bad idea for longer durations in hot weather, but it works well for shorter durations, and it can be used in addition to normal hydration strategies.

What To Look Out For

I don’t feel that getting thirsty is a sign for concern, but there are other things to worry about.

If you start getting a woozy feeling, that’s not good.

If your urine is dark yellow or brown, that’s not good. If you haven’t peed in twelve hours, that’s probably not good either!

Ceasing to sweat is also a cause for concern.

Also, too many pee breaks is a bad sign because you’re probably drinking too much and wasting time with the pit stops!

Understanding the “Drink Before You’re Thirsty” Rule

As I briefly mentioned earlier, if you’ve been involved in endurance sports for more than a day, you’ve probably heard the old “drink before you’re thirsty” rule. This saying has been around longer than I can remember, and it’s still common.

The other saying that goes along with this one is, “if you get thirsty, you’re already dehydrated.”

While proper hydration is important, these sayings should be taken as loose guidelines and not strict rules. A better guideline would be “don’t forget to stay properly hydrated,” but that’s easier to forget, and is probably the reason someone came up with the scarier rules that imply if you don’t drink like crazy, you’ll die.

There’s just something about the threat of death that keeps the idea fresh in your mind!

Unfortunately, some people take these ideas too far. They think that “drink before you’re thirsty” means “gulp down lots of water at every opportunity.”

Don’t do it! You do need to keep drinking to get enough water, but you can actually go overboard and consume too much water. Drinking too much water could lead to hyponatremia, a condition potentially more dangerous than dehydration! (Hyponatremia is a condition where there’s too much water in the body, which dilutes the sodium content, and can cause such things as swelling of the brain.)

Want an example? Take the 2004 Boston Marathon. After a cool spring where temps were generally around 45 degrees, race day shot up to 85 degrees or warmer. It was ridiculously hot and sunny, and runners were downing every glass of water they could get.

When I saw runners in the medical tents, I figured many of them were suffering from dehydration, considering the unseasonably hot weather. But then I saw the news days later, and it turned out that many runners were suffering from hyponatremia. Apparently the warm weather reminded people to “drink, drink, drink” a little too much plain water.

Since you probably want to avoid both dehydration and hyponatremia, here are a few tips:

1. Use Sports Drinks or Electrolyte Replenishing Beverages.

If you’ll be exercising for a long period of time and/or out in extremely hot weather, you should consider using a sports drink rather than plain water. Sports drinks contain electrolytes such as sodium, potassium, and magnesium, which should help keep your body in balance. (Though it’s not a guarantee.)

2. Keep Drinking.

You need to drink, but you only need a few sips at a time, rather than numerous big gulps. I typically have a few sips from my water bottle every 10-15 minutes, depending on the weather. That allows me to stay on a consistent schedule, and means I consume about 16-20oz of water or sports drink per hour.

3. Hydrate Properly.

Follow the guidelines I wrote above when it comes to amount of fluid to consume.

Parting Thoughts

I suggest following these tips rather than relying on old, vague sayings such as “drink before you’re thirsty.” I have gotten thirsty plenty of times while relying on my personal guidelines, but I have never been in danger of serious dehydration.

Show References

This article was originally published on May 3, 2010. It was updated and republished on June 25, 2018.

Levi Bloom is an experienced endurance athlete who has been training and competing for over 17 years. A former Cat 1 road and mountain bike racer (professional class on the regional circuit), he is now a cycling coach (USA Cycling Level 3 Certified) and sports nutrition coach (Precision Nutrition Level 1 Certified).

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2 Comments
  1. Great tips, thanks! I never thought so many factors could be analyzed for the hydration equation!

    I abide by the “drink before you are thirsty rule” but I don’t drink uncomfortable amounts of water. Usually works for me.

    • @Tim

      I tend to follow the “eat before you’re hungry” rule, but not the “drink before you’re thirty” rule, since I get VERY thirsty, VERY quickly, VERY often during intense workouts and races! There’s simply no chance for me to drink before I get thirsty. 🙂

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Hi, I'm Coach Levi. I'm a USA Cycling Certified Level 3 Coach as well as Level 1 Certified with Precision Nutrition. Want to feel better, ride faster, and look great? Let's work together!

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