For some reason, it’s just hard to remember to drink enough water throughout the day. And while we all know the importance of guzzling H2O, especially as the temperatures rise, it’s even more crucial for runners to hydrate properly when you’re trying to log long runs in the heat.
And when it comes to your water intake, there are plenty of questions. So we tapped Heather Milton, M.S., RCEP, C.S.C.S., an exercise physiologist and clinical specialist at NYU Langone’s Sports Performance Center and Katie Kissane, R.D., C.S.S.D., at UCHealth in northern Colorado to break down everything you need to know about hydration.
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How much water should you drink each day?
In general, about 60 to 80 ounces of water is adequate for most people in a day. One way to calculate how much you should be drinking is to halve your body weight, and drink that number in ounces. However, this isn’t perfect, as it may be too much for someone who is overweight and not enough for someone who is underweight, Kissane explains.
Kissane suggests starting your day with about 16 to 20 ounces in the morning after waking up to rehydrate after a night of sleep, and then continue to drink all day to prevent the onset of dehydration. If that seems excessive, it’s important to remember that once you start to feel thirsty, that’s an indication that you are already dehydrated.
“I also do not recommend drinking excessive amounts in the evening as this may cause the athlete to wake up to pee several times at night,” Kissane says.
Also, everyone’s kidney function is different, so spacing fluids out throughout the day helps to maintain healthy kidneys, Milton says. One way to help facilitate this would be filling a water bottle that holds roughly 20 ounces and drinking half of that each hour.
You also have to consider how much fluid is consumed in other beverages like teas and coffee. (Yes, they are diuretics, but so is water.) Fresh foods also have higher water content than dried or processed items, and all count toward your daily intake. An individual who eats all fresh foods with tons of vegetables at meals may need less water than someone who eats microwave dinners for meals, Milton says.
Should your pee actually be clear?
“Nope, light yellow is appropriate. Clear is an indication of possibly too much water intake,” Milton says.
One thing to keep in mind medications and some foods can change the color of urine, so if you are on antimalarials, antibiotics, or a number of other medications, these simple color rules may not apply.
Should runners drink more than the recommended amount?
Yes, athletes do need to consume more than the recommended amount on training days. They can start with the 60- to 80-ounce recommendation and add fluids according to how long they are training. Each athlete’s needs are different, and it can be difficult to determine exactly how much more water to drink, because things like altitude, heat, and humidity can affect how much fluid is lost through sweat, Kissane says.
One way to see how much additional water you need is by determining your sweat rate. To do that, weigh yourself before and after a one-hour workout, and drink 16 to 20 ounces per pound that is lost.
“[Weighing yourself] may not be feasible, so I always encourage an athlete to consume fluids throughout the day and monitor their urine,” Kissane says. If urine is clear or slightly yellow, that’s a sign that you’re hydrated. If it is dark yellow, you need to drink!
How much water should you drink before exercise?
Ideally, you’ve already been hydrating throughout the day, so having about 16 to 20 ounces in the hour prior to exercise should be good—but don’t chug water immediately before heading out the door for a run, because it might make you feel full, Kissane says.
Adds Milton: “Try not to drink so much water before exercise that the stomach is distended.”
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On a long run, how often should you stop for water breaks?
What are the dangers of being dehydrated?
When you’re running outside, especially in the heat, dehydration can make it more likely that someone would succumb to heat stroke. Dehydration also can cause painful muscle cramping, which can impact athletic performance. If an athlete is dehydrated, and they drink excessive amounts of water without replacing electrolytes, they can cause a dilution of electrolytes in the body, which can lead to a dangerous condition called hyponatremia (low sodium levels in the blood), Kissane explains.
Someone is doing moderate to intense exercise in hot and/or humid environments for an hour or longer should consider having an electrolyte drink before or during exercise and possibly afterward, Kissane says. This does not have to be a sugary beverage, but could be a tablet or unsweetened electrolyte powder they add to water.
Another option is to consume something salty, such as pretzels, before the workout and have a food rich in both potassium and sodium such as a fruit smoothie with fruit and yogurt.
What are the dangers of being too hydrated?
Overhydration can which can lead to exercise-associated hyponatremia, which means you have too much water and not enough sodium in your blood. Symptoms of hyponatremia include nausea and vomiting, headache, confusion, and muscle weakness or cramps. If hyponatremia becomes severe, there is risk for seizures, coma, and even death.
A recent study published in Wilderness and Environmental Medicine found that to help avoid hyponatremia, you should be careful not to overhydrate during exercise, if you’re doing longer exercise, especially in the heat (such as training for a marathon or ultra), you should consume sodium or salty snacks along with water, and drink to thirst—being careful not to drink too much.
Though you’ll want to be careful not to consume too much sodium as you work out, as it can cause you to become thirstier and overhydrate, leading to hyponatremia—the exact condition you were trying to avoid by consuming sodium, previous research has found.
How do you know if you’re hydrated?
“If your urine is straw- or lemonade-colored [pale yellow], you are usually good. You can also tell by the frequency of urination. If you are [using the bathroom] every few hours, that is a good sign,” Milton says.
Another way it to check your skin. If you pinch your arm and the skin snaps back quickly, it is a sign of better hydration, Milton adds.