Liquid science: take this crash course in hydration 101 and your performance in the gym will get an A+

Muscle & Fitness/Hers, July, 2002 by Stefanie Ellen Jackenthal

With store shelves overflowing with various kinds of sport drinks, figuring out which brew to drink for your workout and when can be as confusing as high school chemistry. Some are for preworkout, others for during, and then there are those that help with recovery. It's a downright headache in a bottle, can, scoop, or whatever your pleasure.

Of course, sports drinks are of limited use if you can't bring yourself to swallow them. "The most important issue even before discussing what and when you should drink is the matter of taste," insists Mark J. Klion, MD, of Manhattan Orthopedics and Sports Medicine Group in New York. "If it doesn't taste good, it's likely that you won't drink it." That's why you should buy a single serving of a drink first to determine if you like it before buying a dozen or more. M&F HERS has done numerous taste tests of these products over the years, and the one truism that has emerged is that what one woman considers tasty, another thinks tastes like poison.

Sports drinks provide fluids and fuel, but they also add calories, so you need to choose wisely. As researchers frantically work to find new formulas to aid in every phase of your workout, a lot of confusion has flooded the fitness world. We mop up after the sports drink deluge by explaining when you can benefit most from the various drinks available.

Q When is just water enough?

Water is essential for regulating body temperature, blood flow and a whole host or other necessary bodily functions. Water literally keeps you from overheating -- when you sweat, the resulting evaporation of moisture cools your skin. During activities lasting an hour or less, you should sip 4-6 ounces of water every 15-20 minutes.

Of course, since water is calorie-free and healthy for your body in a number of ways, drinking it is the easiest and best way to maintain your hydration levels throughout the day Studies have shown that proper hydration before a training session enhances performance and long-term results. "Even a 2% loss of body fluid can compromise physiologic function and impair performance," says Veronica Fortunato, MS, RD, of the American Health Foundation in Manhattan, New York. "For example, dehydration increases the rate of perceived exertion and decreases time to exhaustion." She recommends drinking 2 cups of water within two hours of exercising and another 1-2 cups 15 minutes before activity; so you can start your workout fully hydrated.

When: Before, during and after your workout.

Q When are "-ades" (6%-8% carbohydrates) the right choice?

We typically have enough stored glycogen (a limited energy source stored in muscles and the liver that gets converted to glucose when your body demands energy) in our muscles to get us energetically through at least an hour of exercise. After 2-3 hours of sustained activity, glycogen reserve levels become low. Glycogen depletion and dehydration are the two leading causes of muscle fatigue. If you don't refill those reserves, you'll experience what's known as "the honk" or "hitting the wall" -- when your muscles are on empty and blood sugar levels are in the gutter.

Over the last two decades, it has become widely accepted that athletes who consume sports drinks containing 6%-8% carbohydrates, like Gatorade, can exercise longer than those using just plain water. If your workout is less than an hour, plain water is a fine choice. If you'll be engaging in an endurance activity (running or biking, for example) at a nonstop pace for more than an hour, however, an "ade" drink may be of benefit. "Four to 6 ounces of fluid should be consumed every 15-20 minutes throughout the session," Klion advises. "Prior to exercise that will last longer than one hour, 6-8 ounces of a light carbohydrate drink should be consumed." He notes that trial and error is the best method of finding out what's right for you.

Low-carb sports drinks (usually a mix of fructose, glucose and sucrose) like Gatorade and Powerade taste good, thus encouraging you to drink more fluids. The electrolytes (sodium, potassium) aid in water and carbohydrate absorption, muscle contraction and relaxation, while the carbs are easily converted into glucose to refuel dwindling glycogen stores.

When: Before and during exercise, especially in hot and/or humid conditions for prolonged periods.

Q Do I need a high-carbohydrate drink?

Probably not. High-carb drinks are for ultra-endurance activities like 100-mile bike rides and five-hour hikes, when your body is engaged in low-intensity activities for multiple hours. They can contain as much as 110 grams of carbs per serving.

Edmund R Burke, PhD, author of Optimal Muscle Recovery (Avery, 1999), explains, "Depending on body size and level of fitness, endurance (not weight-training) athletes should take in 50-90 grams of carbohydrates per hour during exercise." That's fine for endurance athletes, but if you're training in the gym, it translates into way too many calories. There's a limit to the amount of stored glycogen your liver and muscle tissues can handle and the excess glycogen is stored as bodyfat -- probably the last thing you want.