Hydration for Running: A Beginner's Guide

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runners drinking water from handheld water bottles

Staying properly hydrated is one of the keys to comfort and performance while running, whether you're hitting the trails or roads. The benefits can include more energy and endurance, and a decrease in recovery time after a long, challenging run. To help you stay hydrated on your runs, this article looks at:

Video: How Much Water to Bring on a Run

How Much to Drink Before, During and After Running

A graphic showing how much water to drink before, during, and after a run

How much you need to drink depends on how long you are running and how much you are sweating, but here are some good basic guidelines for a run lasting 45 minutes or longer:

  • Pre-hydrate: For a sustained fast-paced run, consider drinking 17-20 fl. oz. about two hours before your run so you'll start off properly hydrated.
  • Maintain hydration: Drink about 5-10 fl. oz. (or a few good long drinks) of water every 15-20 minutes while running.
  • Drink after: Post-exercise hydration gets your fluid levels back to normal and can help with recovery. For every pound lost while running, drink 16-24 fl. oz. of water.

If you're doing a short run, say one that lasts 45 minutes or less, you may be able to forgo drinking water while you're out there. But it's never a bad idea to carry water, especially if it's really hot outside and you'll be sweating a lot. Many runners carry and drink water regardless of how long they'll be running.

To learn about how to carry your water, see our article How to Pack Your Running Gear.

What to Drink Before, During and After Running

A runner dropping a sport drink tablet into a water bottle

While you sometimes hear about runners drinking liquids like coffee, soda or milk before, during or after a run, water is truly your best option. For a more strenuous run, consider a sports drink.

Sports Drinks

When you sweat, you lose electrolytes (minerals in your body), and if you lose too many, your performance can suffer. To compensate for the loss, focus on replacing sodium and potassium, as well as calcium and magnesium. One way to accomplish this is by drinking water and snacking on foods rich in these minerals. Another way to maintain mineral levels is to consume an electrolyte-replacement sports drink.

Look for a sports drinks with a low concentration of carbohydrates (no more than 8%); a higher concentration may upset your stomach. A 6% solution of sports drink has about 14 gm of carbohydrates for every 8 fl. oz. and should contain about 28 mg of potassium and 100 mg of sodium. You can buy convenient powders and tablets to premix with water before a run or to carry with you while you're out there.

Some sports drinks also have caffeine and/or protein. Others have significant amounts of calories. These drinks can be good choices if you have trouble stomaching bars, gels or chews while running. You may have to experiment with sports drinks to find what you like and what sits well with you. Bear in mind that if you're drinking sports drinks and eating energy food, you'll want to keep track of how many carbohydrates you're ingesting and try to limit your intake to less than 60 grams per hour—unless you know your stomach can handle more. To learn more, read Runners' Nutrition Basics.

Recovery drinks: Beverages with protein are typically designed more for recovery and should be consumed after a workout. Providing protein to depleted muscles may possibly help them rebound more quickly.

To learn more, read How to Choose Sports and Energy Drinks.

Hydration Tips

A runner wearing a running hydration vest

Plan your route: Water weighs a lot (16 fl. oz. is just over a pound), so if you want to avoid carrying extra weight while you run, plan a route that will take you by a water fountain where you can drink or refill a bottle. Another option is to use your car like an aid station and plan a long run that does loops from your vehicle. You can stop at your car to refill a water bottle and grab a quick snack.

Set a timer: While running, it's easy to zone out and lose track of the last time you drank. Set a timer on your watch to sound an alarm about every 20 minutes as a reminder to drink and eat some food.

Keep fluids available: Whether you use a handheld water bottle, a hydration waistpack or belt, or a hydration vest, the key is always to keep your water or sports drink accessible. Try not to stop running in order to drink. Doing so will slow you down and you likely won't stop frequently enough to stay properly hydrated. Learn more about carrying your water and other essentials by reading How to Pack Your Running Gear and How to Choose a Running Hydration Vest.

In more remote areas, either carry enough water to get you through the duration of your outing, or bring along a water treatment option for refilling from a lake or stream along the route.

Preventing Dehydration

Dehydration occurs when the loss of body fluids, usually through sweating, exceeds the amount taken in. If you don't counteract this by drinking water, you risk becoming dehydrated. The following signs are a tipoff that your fluid intake is insufficient:

Early signs of dehydration:

  • Dry mouth
  • Decrease in energy or running performance

More serious symptoms of dehydration:

  • Cramps
  • Headaches
  • Nausea
  • Dark or brightly colored urine with less volume. (Note that certain foods and drinks, like those containing B12 vitamins, can cause urine to be bright yellow, so urine color isn't as reliable as other symptoms.)

The remedy for dehydration is simple: Drink water. It's better to take frequent sips of water rather than chugging larger amounts infrequently. Adding in sports/energy drinks can help restore carbohydrates and electrolytes.

Weighing yourself before and after running is an oft recommended practice. If you have lost several pounds, then you're probably not drinking enough water. On a long run you're likely to lose some weight, too, so this also reveals your need for rehydration afterward. The more precise you are in matching pre- and post-run conditions (e.g. both times with an empty bladder), the more reliable your weight-loss data will be.

Preventing Overhydration

The flip side to dehydration is overhydration, or hyponatremia. This is a fairly rare condition that mainly affects endurance athletes such as marathon runners, ultrarunners and triathletes.

In hyponatremia, sodium levels in the blood become so diluted that cell function becomes impaired. In very extreme cases, hyponatremia may cause coma and even death.

The symptoms of hyponatremia are similar to dehydration: fatigue, headache and nausea, causing some runners to mistakenly drink more water and exacerbate the issue.

Preventing overhydration: Drinking compulsively to prevent dehydration can instead lead to hyponatremia. The key to preventing overhydration is to monitor how much you drink.

  • Don't overdrink: Stick to drinking about 10 fl. oz. about every 20 minutes and try not to drink more than you sweat. Weight gain during a run is a telltale sign that you're drinking too much.
  • Maintain a healthy sodium level: Keep your sodium level in balance by eating snacks that contain it or drinking a sports drink with sodium.

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