What to Drink and When

Even if you’re a desk jockey, running your fingers up and down a keyboard, your body will function best when it’s topped off with fluid. If you work out moderately, maintaining your fluid balance can be as easy as drinking a bottle of water during an hourlong workout. If you exercise long, hard or frequently, replacing the fluids lost through sweat is an even bigger priority and requires more precise attention. Here’s a quick guide:

Drink Before. You’ll have more of a flow of water into your small intestine, where it is absorbed into the bloodstream, if you have fluid in your stomach before you start exercising. The American College of Sports Medicine advises that all exercisers swallow at least 17 ounces (a bit more than 2 cups) of water two hours before exercising.

Drink During.Throughout a workout, you should continue to drink every 15 minutes, regardless of whether you feel thirsty. You might want to set your sports watch so that it pings every quarter hour to remind you. Ideally, by the end of each hour you will have finished off at least one full 16-ounce water bottle.

Drink what you need. If your workout lasts under an hour, water is all you need. For workouts lasting one to three hours, a drink with 6 to 8 percent carbohydrate (14 to 19 grams per 8 ounces) will help maintain your blood-sugar level so you’ll last longer. For workouts longer than three hours, a 6 to 8 percent carb drink with at least 220 mg of salt will replace the fluid, energy and salt you’re losing.

Make it tasty. If you like what’s in your water bottle, chances are you’ll drink more of it. A good taste helps and, oddly enough, so will salt. Some salt in the drink not only helps your body maintain a healthy fluid balance but stimulates thirst as well. Since thirst lags behind your actual need for water, a slightly salty beverage will help you stay hydrated.

Check your weight. Ideally, weigh yourself before and after each workout. Here’s how: Before your workout, urinate; then weigh yourself. After your workout, during which you should drink every 15 minutes, urinate and weigh yourself again. The difference is sweat loss. If you lose more than 2 percent of your body weight (3 pounds for a 150-pound person), you’re not drinking enough. If you gain weight during a workout, or during a period of regular workouts, you may be drinking too much.

Do a pee peak. Every time you urinate, you should do a color and quantity check: Your urine should be copious and clear. Some vitamin supplements can add color to urine; that won’t affect your level of hydration.

Watch for signs of dehydation. Besides a drop in body weight or darkly colored urine, signs of dehydration include dry mouth, thirst, irritability or apathy, headache, dizziness, cramps, chills, nausea or vomiting, head or neck heat sensations, and excessive fatigue.