Mistake #1 Compromising on carb-loading
Many people fear ingestion or weight gain issues, however, when training to perform well carb-loading will increase your performance by boosting muscle glycogen stores. These muscle glycogen stores are your energy store and the more you have stored, the longer you will ward off fatigue.
Solution: Practice your carb-intake (1-2 days before long runs) during your training months (note: keep fat low). Aim for 4-5 grams of carbs per pound of body weight. For example, I weigh 162 pounds, so I would want to aim for 648-810 grams pre-race.
Mistake #2 Skipping breakfast on race morning
Being nervous or the fear of standing in line at a port-o-potty before or during the race is enough to ward off many racers from eating breakfast. However, by not eating breakfast you are not restoring your liver glycogen. Liver glycogen has two primary purposes for a racer, it indirectly keeps your blood sugar levels normal so you can concentrate and think clearly and it provides fuel for exercising muscles.
Solution: Once again practice eating what you plan to eat on race morning on your long runs during training 1-4 hours before you head out. Aim for 50 grams of carbs for each hour before "go time" your eat; for example if you eat two hours before you go run, you'll want to aim for 100 grams. If you have a sensitive stomach, opt for a liquid breakfast, because it will empty from the stomach faster.
Mistake #3 Over hydrating before or during the race
Over hydrating can cause hyponatremia, which is characterized by low blood sodium levels.
Solution: In days leading up to your race drink to thirst and keep an eye on your urine. You want your urine to be the color of lemonade... too dark=dehydrated, too light=over hydrated. Eat salty foods and rehydrate with sport drinks leading up to the race, consuming sport drinks on race day can help as well.
Mistake #4 Avoiding sports drinks during races
Many runners, including myself, blame sport drinks for upset stomachs, causing runners to drink only water.
Solution: As with the other solutions, practice training your stomach leading up to the race. Find out what drinks work for you best. Many runners and races water down their sports drinks, which is what I did and that worked for me better. Aim to drink 2-6 ounces every 15-20 minutes... this varies depending on how much you sweat and how hot it is outside.
Mistake #5 Not refueling early enough
This is a common mistake for runners at all levels. Be sure not to skip those first few water stations, refueling and rehydrating steadily throughout the race is important. Don't wait until you "hit the wall", this will make the remainder of the race difficult
Solution: During the race aim to consume 30-60 grams of carbs an hour from the beginning. Be sure to plan and practice ahead of time what drinks or sport foods you are going to use.
Do you have any common nutrition mistakes to add to this list?