Long-distance running requires a lot of exertion, and that means that body of yours has to prioritize its functions. Digestion is not at the top of the list; redirecting blood flow to those hard-working muscles is. That's why foods that might normally bother you will feel heavy on your stomach and may even cause nausea, vomiting and other less-than-pleasant forms of intestinal distress [source: Run the Planet]. Proteins and fats take the longest time to digest, anywhere from three to five hours. Cheeseburgers, hot dogs, steak, chicken and fish -- they may be the main components of a great Saturday afternoon barbecue, but they're not the foods behind a good run.
Sugary drinks also have the potential to cause stomach upset during a run. Experiment with mixing sports drinks with a smaller concentration of powder if you find this to be the case. Carbonated beverages are a sure-fire source of bloating for obvious reasons. Just as a shaken bottle of soda creates unwanted fizz, a jostled stomach of your favorite beverage will do the same.
A good nutritional defense isn't just about what you eat. It's also about when you eat it. You should eat a light meal, high in carbohydrates a couple of hours before you head out on your adventure. This will allow enough time for digestion while also ensuring that your liver and muscles are topped off with the most glycogen they can hold. The notion that a runner can avoid discomfort by exercising on an empty stomach ignores the fact that you're far more likely to hit the proverbial wall -- complete depletion -- and it avoids the unpleasant truth that even an empty belly can become irritated.
Now that you know how to defend yourself against common nutritional mistakes, click ahead to learn how to go on the offense.