Quick: When’s the last time you took a sip of water? If you can’t answer that, you probably need to go pour yourself a glass. Hydration is one of the most important aspects of physical performance, but it’s one that too many people overlook.
Dehydration can kill your endurance and increase fatigue, recent, according to the Centers for Disease Control and Prevention (CDC). And the majority of healthy people meet their daily hydration needs by letting thirst be their guide, reports the National Academy of Sciences, Engineering, and Medicine (NASEM).
But in the same way you adhere to a training regimen and meal planning, you need to put effort into proper hydration 24/7—not just before and after a workout. “Don’t wait until you’re thirsty,” says Jaclyn Sklaver, C.S.C.S., a sports nutritionist and founder of Athleats Nutrition. “By the time you’re thirsty, you’re already dehydrated. And once you’re dehydrated, you’re playing catch-up.”
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So, how much water should I drink?
You’ve probably heard the ol’ eight-cups-a-day rule, right? The official recommendation from the National Academy of Sciences, Engineering, and Medicine (NASEM) is that men consume approximately 125 ounces (about 15 and a half cups) and women consume approximately 91 ounces (about 11 cups) of water each day. Total, meaning about 80 percent—or eight to 12 cups—of that fluid comes from drinking water and beverages, while the other 20 percent comes from water-rich foods.
Of course, every body is different, and “there is no hard and fast rule about dehydration,” says John Brenkus, the creator and host of Sport Science on ESPN and author of Perfection Point. If you’re a regular exerciser, though, it’s safe to assume that you’re probably going to need to bump up your baseline water intake due to how much fluid you lose while working out, he adds.
To figure out how much fluid you’re losing on the run, weigh yourself before and after an hour of running or training. Each pound of weight loss is approximately equal to 16 ounces of fluid deficit. From your pre-run weight, subtract your post-run weight plus your fluid intake during the run to find your individual sweat rate. Then you can figure out how many ounces you should be sipping per hour while you run, or how much you need to drink post-run.
“The gold standard I generally recommend is drinking half your bodyweight in ounces, plus eight ounces for every half hour of exercise,” says Sklaver. If you’re a 140-pound runner who works out for an hour a day, that would translate to about 86 ounces—not too far off from NASEM’s recommendations.
What are the symptoms of not drinking enough water?
Dehydration occurs when you lose more fluid than you take in. “Water is helping to move everything in your body,” explains Brenkus. It’s the vehicle by which oxygen and nutrients get to your cells, he adds.
Think about it this way: Your body is 60 percent water, and your muscles are 75 percent water. “Literally every cell in your body requires water, so when you don’t have enough of it, your bodily functions are going to be less efficient,” says Sklaver.
Symptoms of dehydration include a rapid heartbeat, rapid breathing, extreme thirst, less frequent urination, dark-colored urine, fatigue, dizziness, and confusion; if you get dehydrated enough, you can even experience heat exhaustion and heat stroke.
These symptoms can feel bad enough in a normal environment, but can be significantly exacerbated when your body is under a significant amount of stress—like during exercise (picture Shalane Flanagan's finish-line collapse Sales & Deals).
What happens to your running performance when you don’t drink enough?
Shoes & Gear research published in Dehydration can kill your endurance and increase fatigue, recent Heres the Worlds Simplest Hydration Plan study determined that dehydration of just two percent of your body weight leads to a higher rate of perceived exertion and a reduction in endurance performance (translation: exercise feels harder, so you don’t perform as well).
As Brenkus said earlier, water helps expel oxygen through your blood to your cells. It also moves electrolytes—essential minerals like sodium which help regulate nerve and muscle function—into your cells. “It’s fueling the mechanism by which your body is even working,” he says.
Plus, if you’re dehydrated, it’s going to limit your ability to sweat. Sweat is your body’s defense mechanism agains heat, says Brenkus. When you sweat and that liquid evaporates from your skin, that’s what cools you down. “If you’re so depleted of water that you can’t sweat, your body has no way to cool itself,” he explains. And that makes for very dangerous scenarios that can lead to heat exhaustion or heat stroke, which can be fatal.
What if I feel like I can’t drink enough water?
It’s not that it’s hard to drink eight cups of water per day. But some people get caught up in their days and forget to drink, some people feel too lazy to get up and fill a glass when they should, and some people just straight-up don’t like the taste of water. Whatever your excuse is, it’s just that: an excuse.
One of the best things you can do to make sure you hit your H2O quota is to start your day on the right foot. “I tell people to have 16 ounces of water as soon as you wake up,” says Sklaver. Then, structure your drinking around your meals. If you drink one to two cups of water at each meal, drink a bottle of water during a workout, and then drink another bottle post-workout, you’ll easily hit 12 to 16 cups.
HidrateSpark Steel Bluetooth Smart Water Bottle
HidrateSpark Steel Bluetooth Smart Water Bottle
If you’re someone who responds well to metrics, use a water bottle like Hidrate Spark to track your fluid intake. The sensor in the bottle will actually blink to alert you when it’s been too long since your last sip.
You also don’t have to just drink water for the tap. There are a number of flavored waters or powder tablets that add a pop of taste without a ton of (or any) additional calories. “You want to find drinks that aren’t taxing your system with synthetic ingredients or high amounts of caffeine and sugar,” says Brenkus. The simplest solution: drink infused water by dropping a few slices of lemon, lime, or cucumber in a pitch of water for a natural flavor.
Another easy tip: Pack your plate with water-rich foods to up your intake at meals. Cucumbers, iceberg lettuce, tomatoes, celery, zucchini, and sweet peppers all have a water content of over 90 percent.
