5 Common Pre-Race Nutrition Mistakes

Completing a marathon is a monumental undertaking. Whether it's your first or your 20th, a marathon requires stamina, mental fortitude and a bit of luck--just to get to the starting line. Runners who put nutrition on the back burner and concentrate solely on their training will find it especially tough on race day. (The same holds true for runners moving up from 5ks and 10ks to longer endeavors like 10 milers and half marathons.) Whether you're a new marathoner or a veteran, turn in a truly peak performance by avoiding five common race day nutrition mistakes.

1. Compromising on carbohydrate-loading.

The fear of digestive problems or anxiety over weight gain leads many women to skimp on this performance-enhancing step. Carbo-loading, which boosts valuable muscle glycogen stores, won't magically help you run faster. However, it works by helping delay the onset of fatigue, allowing you to maintain your desired pace. The key is to consume a higher-than-normal percentage of carbohydrate-rich foods for three days prior to the race while concurrently resting or performing limited exercise. Another bonus: the three grams of water stored, along with every gram of glycogen, helps to delay dehydration during the race.

The solution: Practice a modified version (one to two days of carbo-loading) before long runs in the months leading up to race day. Concentrate on carb-loading, not fat-loading. Aim for 4 to 5 grams of carbohydrate per pound of body weight. Gain confidence from the fact that slight weight increases are a sign of proper carbo-loading. If you do experience some stiffness or heavy legs, it dissipates as you start to run.

2. Skipping breakfast on race morning.

A nervous stomach, or fear of standing in the port-a-potty line as the race starts, keeps many marathoners from eating a light to moderate pre-race morning meal. If you skip breakfast, you fail to restore liver glycogen stores after being depleted overnight. Liver glycogen is converted back to glucose to maintain normal blood sugar levels, which helps you to think more clearly and remain positive. It also provides fuel for exercising muscles, especially during prolonged exercise.  

The solution: Eat one to four hours before start time. Aim for 50 grams of carbohydrate for each hour before the start. Choose familiar foods you enjoy. Practice before long runs with the same foods you plan to eat on race day. If you have an ultra-sensitive stomach, opt for a liquid breakfast, such as a meal-replacement beverage. They empty from the stomach faster than solids do and contain less fiber.

3. Over-hydrating before (or during) the race.

Women runners in particular need to be aware of the dangers of over-hydrating before (and during) endurance races. Hyponatremia is a dangerous medical condition characterized by a low blood sodium level. It results when you replace the fluid, but not the sodium, lost through sweating by drinking large amounts of water or low-sodium fluids. Due to a smaller starting blood volume and a penchant for "following the rules," females are more at risk for overdrinking prior to and during prolonged exercise.

The solution: In the days leading up to the marathon, drink to thirst. Monitor your urine color--it should be pale yellow like lemonade, neither too dark (dehydrated) nor clear in color like water (increased risk of being over-hydrated). Consume a modest amount of salt, especially if you'll be racing in warm or humid conditions. Use the saltshaker, eat salty foods and hydrate with an electrolyte-containing sports drink.

4. Avoiding sports drinks during the race.

Erroneously blaming sports drinks for stomach issues leads many marathoners to opt for only drinking water during the race. Compared to water, sports drinks do triple duty, conveniently supplying the fluid, electrolytes (especially sodium) and easily digestible carbohydrate that every marathoner requires during an endurance effort.

The solution: Train your digestive tract: Determine in advance what sports drink will be provided along the course and practice drinking it on long runs. Design a hydration plan that matches your sweat losses.  Aim to drink 2 to 6 ounces every 15 to 20 minutes while on the move.

5. Not refueling early enough.

Ignoring the need to refuel in the early stages of a marathon is the undoing of veteran and new marathoners alike. Well-rested racers, as well as inexperienced marathoners, often get lulled into skipping early aid stations because they feel good and everything is going to plan. Waiting until you've "hit the wall" typically means a horrendous final leg of the race, as playing catch-up is futile at this point.

The solution: Consume 30 to 60 grams of carbohydrate per hour right from the start (with water provided at aid stations). In addition to sports drinks, experiment with carb-rich sports foods like energy gels, chews and bars. Practice consuming these products during your training, too). Make sure to plan how you will carry these items on race day.

Suzanne Girard Eberle, RD, CSSD, author of Endurance Sports Nutrition-Second Edition, is a board-certified sports dietitian in Portland, Oregon. Find her at eatdrinkwin.com.

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