Staying hydrated before, during, and after exercising helps your body perform at its best. The importance of hydrating can’t be understated — the human body can take on extreme physical endeavors, however we can’t survive more than three days without water.
When you don't get enough water, every cell of your body is affected; when you sweat, you lose electrolytes, which are essential to your body's functions.
Read more about signs of dehydration and tips for running in summer heat in our Running in Hot Temperatures guide.
Note: These are general guidelines to maintain well-being while exercising. Please talk with a healthcare professional or trainer if you feel you are not drinking enough water.
Drinking water before a run is just as important as hydrating after the run.
As a rule of thumb, drinking 8 ounces each hour throughout the day ensures good hydration levels; at a minimum, drink 16 ounces of water two hours before you run.
Depending on the length and duration of your run, the amount of water you drink will vary.
On a light run (less than 45 minutes), drinking water is fine. Runs 4 miles or less don’t necessarily require you to carry fluids.
On a longer run (greater than 45 minutes), drink sports drinks every 15–20 minutes to help you maintain electrolyte levels. On a run longer than 4 miles, carry liquids or sports gel. Sports drinks and gels help you to maintain vital electrolytes, such as sodium and potassium.
To maintain access to fluids during a run, carry small squeeze bottles in a belt worn around your waist. For your long runs where you can't carry enough fluids, plan to return home to refill your bottles, refill at a park fountain, or purchase fluids at a convenience store on your route.
You should rehydrate after your run. If you don’t know how much water to drink, weigh yourself before and after your run.
For every pound lost, drink 16 ounces. You’ll eventually get a feel for how much sweat you lose on a run, and how much you’ll need to rehydrate.
Because your body loses water throughout the day from urination and your sweat glands, you need to replenish your hydration levels.
Although they are technically "liquids", beverages such as soft drinks, fruit juices, and coffee are not the best way to hydrate. High amounts of caffeine can act as a diuretic, further dehydrating you. High amounts of sugar in sodas and fruit juices make those unhealthy options; even drinking sports drinks when not exercising heavily isn’t great. The key is to drink pure water enhanced by electrolytes.
We often see in magazines or hear from friends to drink eight glasses of water a day. Depending on your body and level of exercise, this may be too much or not enough.
Here are a few guidelines we recommend for starters. If you are concerned with how much water you need, talk with your healthcare professional to determine how best to hydrate.
It is oft-touted that if you’re thirsty, you are already dehydrated. While this may be true, everyone is different, and thirst can be an unreliable indicator for hydration. Even factors such as cold weather can make it difficult to rely on thirst as an indicator.
A popular and fairly standard approach is to check the color of your urine. You should be drinking enough water to turn your urine a light-colored yellow.
Dark-colored urine is a sign that your kidneys are retaining fluids in order to maintain your bodily functions, which includes detoxification. As a result, your urine will seem highly concentrated and dark in color. You may also urinate less frequently, for the same reason.
Bear in mind that riboflavin (vitamin B2, which is also found in most multi-vitamins) will turn your urine a bright, almost fluorescent yellow. So if you're taking supplements containing B2, it may be more difficult to judge hydration by the color of your urine.
It is possible to drink too much water, but it is rarely the case. This is called hyponatremia, and it’s caused from an imbalance between water and electrolytes (rather than "too much" water).
As you sweat and lose water, you lose electrolytes. The more intense the workout, the more electrolytes you lose. If you replenish just with water, you will dilute the already-low electrolyte levels in your system. Hence, replenishing with sports/electrolyte drinks or sports gels is crucial for longer runs.
How do you hydrate? Do you have any tips or recommendations for fellow runners? Let us know in the comments!