Fish Fuel

Out of the water, nutrition for swimming performance isn’t markedly different from nutrition for running, hiking and cycling. You still need sufficient carbohydrates to fuel the workout and to reload in preparation for the next one. And of course you must guard against dehydration because being in the water doesn’t mean you don’t dehydrate quickly.

But during actual workouts, swimming is different from other sports in two important ways. First, it’s difficult to eat anything while actually in the water although long distance, open water swimmers learn how to do it out of necessity. So swimmers need to take in a carbohydrate sports drink between laps or interval sets to maintain sufficient energy.

Second, most swimmers don’t realize how rapidly they dehydrate during hard training. Being in the water means you can’t tell how much you’re perspiring and losing fluid as you swim. Also, you get water in your mouth, so it’s hard to tell how thirsty you are until it’s too late.

There’s one more important point unique to swimmers: They usually train early in the morning or late in the evening when the pool is available. In the case of early workouts, this means that you’re swimming hard intervals without breakfast. In most cases, you haven’t eaten anything since dinner the night before—a fast of over eight hours—so muscle glycogen levels are depleted before you start. If you don’t eat dinner before evening workouts, that means it has been six or seven hours since lunch.

Given the specific demands of the sport, here’s how swimmers can get enough calories and fluids to fuel their workouts:

• Start the workout with something in the tank. As you’re heading to the pool, swig about 16 ounces of a sports drink containing 6 to 9% carbohydrate. Most commercial products are in this range. (Check the nutritional information to be sure.) The liquid will digest quickly, making your swim more comfortable, and you’ll have some carbs in your system for energy to fuel the workout.
  
  If you swim in the evening, eat a late-afternoon snack containing about 60 grams of carbohydrate if you’re an average-sized woman, 80 to 100 if you’re a man. How much is that? Most energy bars contain about 40 grams of carbo and a banana packs about 30. Or try a bagel with jam and a handful of raisins or a fruit bar about two hours before your workout. (See sidebar for more choices) These food choices can be eaten unobtrusively at your desk just before quitting time.
  
  
• Prehydrate. You need some calories before the swim, but as we’ve seen, you also need to be sufficiently hydrated. Most people who drink coffee during the workday are chronically dehydrated because coffee is a mild diuretic. And even if you spurn the java, most people don’t drink enough water when they’re busy with the daily grind.
  
  So most swimmers start the workout dehydrated—and it only gets worse from there. Additionally, research shows that it’s difficult to rehydrate with water alone. If you swim early in the morning, the suggested pre-swim 16 ounces of sports drink will hydrate you as well as supply carbs. If you swim in the evening, drink the same amount an hour before the workout, so you start with fluid levels high. If time is short, it’s fine to drink just before the swim, but you’ll have to experiment to find out how much liquid in your stomach you can tolerate during hard efforts.
  
  
• Drink during swims of 45 minutes or longer. Always drink before you feel thirsty. Your body’s sensation of thirst lags behind its need for liquid so when you feel thirsty, it’s already too late. Keep a bottle of sports drink at the end of the pool and every 15 minutes, stop briefly and slug down four to six ounces (several big swallows.) If you forget to drink regularly, check the pace clock as a reminder or structure the workout to include a short break for drinking.
  
  
• Hydrate after the swim. No matter how much fluid you ingest before and during a swim workout you’ll finish depleted. Indoor pools can be hot and humid, but even if you’re swimming outside in cold water, you’ll perspire as you swim and lose water vapor as you breathe. There’s a simple way to be sure you’ve re-hydrated—simply weigh yourself before and after and compare the figures. If you’ve lost weight, it’s water you’ve sweat out, not (unfortunately) fat. You’ll need to drink 20 ounces of fluid for each pound of bodyweight you’ve lost during the workout. Keep drinking until your weight has returned to normal and your urine is plentiful and pale yellow in color.
  
  
• The Glycogen window. One last step—but it might be the most important. Studies show that your muscles replace their fuel (glycogen) much faster and more efficiently if you eat plentiful carbohydrates immediately after endurance workouts. Your goal is to eat 60 grams of carbohydrate (if you’re an average-sized woman) or 80 to 100 grams if you’re an average male. Your muscles will re-fuel best if you down this chow in the 15 minutes after the swim. The re-fueling process becomes less efficient after this two-hour post-workout “glycogen window.”
  
  Notice that the amount of carbohydrate you should eat after the swim is similar to what we’ve suggested you consume before a late-day workout. There’s one exception—research indicates that if you mix four parts carbohydrate with one part protein, your glycogen stores will top off more quickly. That’s as simple as having cereal, a banana and some skim milk for protein.