"Hydrate or die," advises one sports drink company. It's a little aggressive, but not far off. Neglecting to properly hydrate for any extended period of exercise probably won't kill you, but it can ruin your workout and prolong your recovery time. And hydration doesn't just mean drinking water until you pee clear. A good hydration strategy will account for your body's changing state and its changing needs before, during, and after exercise.
If nutrition provides the fuel that powers your engine during strenuous activity, hydration supplies the coolants, lubricants, and hydraulics. You wouldn't run your car through its paces without checking its oil and fluid levels; it's a similarly bad idea to start any workout without being fully hydrated. The aforementioned reference to peeing clear is a good indicator that you're not dehydrated, but it doesn't tell the whole story. The American College of Sports Medicine (ACSM) advises drinking at least 16 ounces of electrolyte solution (electrolyte is a fancy word for sodium—more on that later) in the two hours prior to exercise. What they don't tell you is which solution to drink.
Most athletes find popular "sports drinks" like Gatorade and PowerAde too strong for their stomachs and overly sweet. Drinking them before exercise will likely leave you with a bloated midsection and a sticky mouth. What Gatorade and PowerAde do have going for them, though, are electrolytes, those fancy forms of salt that help us hydrate by helping the body absorb water. Drinking water alone is a little like pouring water on earth that's been baked hard by the sun; consuming an electrolyte solution tills that soil so that water can more easily seep in. The trick is finding a solution that contains sodium (and, ideally, potassium, which helps the body absorb sodium) but doesn't upset your stomach. Many people find that diluted Gatorade works well for pre-hydration, as do lighter drinks like Propel Fitness Water.
Ever noticed that when you sweat heavily, your sweat tastes salty and occasionally leaves salt streaks on your gear? That's because you're sweating more than water—those electrolytes that we use to prime our bodies for hydration seep out along with our sweat. The primary hydration goal during exercise involves maintaining both your fluid levels and your ability to replenish them. Water alone is better than nothing, but a hydration strategy that relies exclusively on water will fail dramatically during very long workouts. All of us have heard warnings about the perils of dehydration, but there's more at stake than just water: As you sweat out water and electrolytes, less and less of the water you drink will be absorbed by your body. Sure, you'll be peeing clear, but as long as your sodium levels continue to be depleted by the act of sweating, you'll be getting increasingly dehydrated with each bottle of water you drink. The condition that results from hydration without electrolyte replenishment is called hyponatremia, a dilution of sodium in the body's cells that causes fluid accumulation and edema formation, especially in the brain. Symptoms include nausea, vomiting, lethargy, headache, and fatigue.
Scary stuff... so how do you avoid it? Simple. First, note that the ASCM points out that hyponatremia can be caused by both a lack of sodium replenishment and—more important—overhydration. Drink what you lose, but nothing more—16 to 24 ounces per hour of activity should do it, depending on how much you sweat and how hard you work. Second, make sure your sports drink contains a weak to moderate solution of sodium. Popular drinks like Gatorade and PowerAde have this solution but are so strong and contain so much sugar that they will upset your stomach. Lighter drinks like Propel Fitness Water are too weak. Your best bet is a product developed specifically for rehydration during endurance athletics. Our picks? Accelerade is an excellent during-workout drink, as is PowerBar's Perform sports drink. Both products come in a variety of flavors and contain the right balance of electrolytes and sugars.
So you've hydrated properly before exercising and dodged dehydration and hyponatremia during that long run. You're in the clear, right? Sort of. It's unlikely that you'll develop exercise-related hydration problems after your workout ends, but the way you refuel afterward can play an important role in your recovery. You have one hour after working out to restore your supply of a critical intra-muscle fuel called glycogen. Eating something high in complex carbohydrates—a bagel, peanut butter and jelly sandwich, or a good energy bar—will do the trick, but sometimes it's hard to stomach solid food immediately after working out. Luckily, a number of companies make excellent post-workout drinks. The label on any good one will show large amounts of simple and complex carbohydrates to top up your glyocgen stores as well as a substantial amount of protein to help your muscles recover. Endurox R4 is a top choice among triathletes and rowers; Cytomax Recovery wins praise from athletes in everything from cycling to bodybuilding.
Finally, it's a good idea to continue drinking water after intense workouts that leave your muscles sore and cause delayed-onset muscle soreness, like hill repeats or weight workouts. The water will flush out the toxins that contribute to your soreness and promote a quicker recovery.
Topher Bordeau is a correspondent for the Rowing News and has written for Men's Edge, N'East, and other magazines. He also makes his living as a collegiate rowing coach and currently works at Dartmouth College.