Hydration 101: How to Stay Hydrated During Long Runs
How Much to Drink Before, During, and After Running
How Much to Drink
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 500 ml of water about two hours before your run so you'll start off properly hydrated.
- Maintain hydration: Drink about 50-150 ml (or a few good long drinks) of water every 15-20 minutes while running.
- Drink after: Post-exercise hydration helps return your fluid levels to normal and can aid in recovery. For every kilogram lost while running, drink 1-1.5 liters of water.
If you're doing a short run, 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.
What to Drink Before, During, and After Running
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 sports drinks with a low concentration of carbohydrates (no more than 8%). A 6% solution of sports drink has about 14 grams of carbohydrates for every 250 ml 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.
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.
Hydration Tips
Plan your route: Water weighs a lot (500 ml is just over half a kilogram), 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.
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
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 often recommended. If you have lost several kilograms, 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 300 ml 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.