Carbs – A Runner’s Best Friend Before a Marathon

I’m running a marathon in 2 days! What does that mean? I get to eat a ton of carbs!

Sounds amazing right? Well actually it’s more complicated that you think. I’ve always “carbo-loaded” before half marathons. Basically, I just tried to eat a lot of bread, rice, pasta and fruit the few days before the race. I never actually calculated what percentage of my diet was coming from carbs or how many grams of carbs I’m eating.

Why We Carbo-load

While carboloading is beneficial for half marathons, it is critical for marathons. Most people won’t hit the dreaded “Wall” during a half marathon, but it’s pretty common during a marathon. The “wall” is the point where your glycogen levels are so depleted that your body literally shuts down and it starts to feel like you are running through quick sand – ie you have no energy left. The best way to avoid hitting the wall is to properly nutrition before and during the race.

According to an article I found on Powerbar.com, typically, if you are exercising at a steady pace and intensity, carbohydrate loading will increase your endurance by about 20%. For example, if you typically can run 20 miles before exhaustion gets the better of you, with supercompensated glycogen stores you may be able to extend that to 24 miles. Or, if your event calls for you to cover a specific distance, such as is the case with a cycling race or a marathon, carbohydrate loading may improve your time by 2-3%. For a four-hour race, that equates to about 5-7 minutes faster. Carbs could make the difference between bonking at 23 mile marker or not bonking at all!

History and Theories on Carboloading

According to Active.com, the practice of carbo-loading dates back to the late 1960s. The first carbo-loading protocol was developed by a Swedish physiologist named Gunvar Ahlborg after he discovered a positive relationship between the amount of glycogen (carbs stored in the muscles and liver) in the body and endurance performance. Ahlborg believed that the only way to efficiently carbo-load was to first deplete the body of carbs by exercising very hard and eating very few carbs. Then the body would be primed for carb intake. Later, however, other research showed that you can increase the glycogen stores without depleting it first. This method is called the No Depletion Method. The most recent research on carbo-loading is called the Western Australia Method, includes a single, very high intensity short workout the day before the race which creates a powerful demand for glycogen storage in both the slow-twitch and fast-twitch fibers of the muscles. They hypothesized that following such a workout with heavy carbohydrate intake could result in a high level of glycogen supercompensation without a lot of fuss.

How to Carbo-load

Although there are several theories as mentioned above, the general protocol for carbo-loading is this:

1. 1-2 weeks prior to the race, begin to reduce the length and intensity of workouts but don’t decrease the frequency. (i.e. run 5 miles easy instead of 6 miles with intervals).
2. About 1 week before the race, increase carbohydrate intake so that you are eating about 50-55% of your calories from carbohydrates.
3. 3-4 days before the event, increase carbohydrate intake to about 70% of your total calories. More specifically, smaller athletes should eat about 4.5 grams of carbs per pound of body weight and larger athletes should consume about 3.5 grams. So a small woman at 120 lbs should eat about 540 grams of carbs and a man at 200 pounds should eat about 700 grams of carbs each day. The key to achieving these levels is to cut back significantly on fats and proteins. You should still include protein, but for example, have two plain rolls for a total of 200 calories rather than 1 roll with butter, for a total of 200 calories.

The problem with this plan is that 1 gram of carbs has about 4 calories. That means that little 120 lb woman should be eating 2,160 calories from carbs alone (if you use the 70% ratio this mean she’ll be eating 3,085 calories total that day).  The average woman that weighs 110 lbs probably eats less than 2,00 calories a day total, let alone from carbs.  To put it into even more perspective, one bagel has about 40 grams of carbs. That means she’d need to eat 13.5 bagels in one day to properly carboload. When I discovered this info (I weigh more than 120 so I will have to eat more than 13 bagels!), I was a little disheartened. I decided to do some further research on carboloading specific to women.  

Carboloading for Women – There is a difference!

Now this was one of the most interesting things I found in my research on carboloading. According to Powerbar.com, on average, female athletes consume fewer calories than their male counterparts. So, even though you may be boosting your carbohydrate intake compared to what you normally consume in order to carbohydrate load, because your total calorie intake is low relative to your male training buddies, you may not actually be getting enough carbohydrates to achieve supercompensation of muscle glycogen stores. For women, carbohydrate loading days are definitely not the time to cut calories, In fact, over consuming calories for the few days that you’re carbohydrate loading may be necessary. And of course, make sure all those extra calories come from carbohydrates. For example, instead of consuming 2,000 calories, you may need to consume 2,600 calories for a few days. Those 600 bonus calories equate to 150 extra grams of carbohydrates.

The menstrual cycle also is a factor for women. Researchers have observed that glycogen storage is likely to be more efficient in the two weeks before menstruation as compared to the week during and after a woman’s period. So although you can’t do much to control your menstrual cycle – women go out and eat before your race!

My Carboloading Routine

Once I discovered how many carbs were really necessary to properly fuel, I researched the carb content of the foods I was planning on eating that day. I counted them up and they only equaled 350 grams of carbs even though I was eating 2,300 calories (which is more than I usually eat). I discovered that things like pita chips, protein bars and fruit don’t’ have nearly as many carbohydrates as I thought. The food items with the most carbohydrate bang for their buck are cereal, rice, pasta and bread (surprise surprise). So I adjusted my diet accordingly and cut out some of the veggies, fat and protein to make way for those lovely carbs. Another suggestion some of the websites I found had was to drink your carbs so that you can get more calories in without filling up (Gatorade and even soda were suggested). I plan to indulge in a beer two nights before the race and drink some sports drink on the day before the race. I also plan to eat quite a few calories over my normal 1,800-2,000 in order to fill my muscles up with carbs. I’m sure it won’t be so hard with the pasta buffet my running group is holding tonight! 🙂

You know that you carbo-loaded properly if you gain weight. Each ounce of carbs stored in your body you also hold three ounces of water. That means that a properly carbo-loaded runner should gain about 3 lbs on race day. Fortunately this weight will fall off during the 26.2 miles you run on race day.

To all my running friends – carb up and enjoy it! We need it!

Sources:

http://www.mayoclinic.com/health/carbohydrate-loading/MY00223

http://www.powerbar.com/articles/224/carbohydrate-loading.aspx