Preparing to Race: The Importance of Carb-Loading

sarah cuff Carb-Loading for Runners, Food for Runners, Training Leave a Comment

Today I began a 3-day carb-loading protocol (also known as carbo loading, or more formally as CHO-loading). I’m doing this because carb-loading has been shown to enhance endurance and the performance of prolonged exercise events (Clinical Sports Nutrition, L. Burke, 2010). And I’m attempting to do it with 100% accuracy because supposedly many runners don’t get it right.

Keep in mind that carb-loading is considered appropriate if your race will last longer than 90-120 minutes. I will be running a marathon on Sunday – so definitely will meet this criteria. If you will be racing for less than 90-120 minutes (for example, a 5k or a 10k race), you don’t need to worry about carb-loading.

Among others to point to the positive benefits of carb-loading, a 1995 study published in the International Journal of Sport Nutrition showed that eating 10 grams of carbohydrate per kilogram of body weight for 3 days prior to a 2 hour cycling time trial succeeded in filling glycogen stores, improving strength and lengthening distance covered. Another study, published in the European Journal of Applied Physiology in 2002 in fact showed that even only 24 hours of intense carb-loading at 10g/kg was enough to fully load glycogen stores.

The most interesting and recent study, completed in 2009 (published in the International Journal of Sports Medicine in 2011) and truer to ‘real life’, looked at 257 marathon runners who ranged in ability and nutritional preparation.The study found that those runners who had managed to eat more than 7 grams of carbohydrate per kilogram of their body weight had significantly faster overall race speeds. They also maintained their running speed during the race better than those who consumed less than 7 grams of carbohydrate per kilogram of their body weight. The researchers concluded that (alongside factors of gender, body size and training) pre-race day carbohydrate intake is a key marker of race performance.

It’s interesting to note that only 31 of those 257 marathoners actually ate the required amount of carbohydrates to enhance performance. This begs the question – how many of us are actually toeing the line with full glycogen stores? My guess would be not as many of us as we think. Consuming between 7 and 10 grams of carb per kilogram (without consuming additional calories) requires some thought and preparation.

First, let’s take a look at what those numbers look like in real life. For each one of the three days leading up to race day:

  • a 125lb individual must eat between 392g to 560g carbs
  • a 150lb individual must eat between 476g to 680g carbs
  • a 175lb individual must eat between 553g to 790g carbs
  • a 200lb individual must eat between 630g to 900g carbs

Here is a list of high-carb foods with approximate carb contents that may help you reach these goals:

  • 1/3 cup dry rolled oats: 20g
  • 1 slice Ezekiel bread: 15g
  • 1 medium banana: 25g
  • ½ a medium cantaloupe: 25g
  • 1 cup fresh grapes: 15g
  • 2 medjool dates: 35g
  • 1 cup tart cherry juice: 35g
  • 1 banana oat muffin (1/12 recipe): 25g
  • 1 slice banana bread (1/12 recipe): 35g
  • 1 power cookie (1/12 recipe): 20g
  • 1 granola bar: 20g
  • ½ cup hummus (¼ batch): 25g
  • 1 serving Mary’s Crackers: 20g
  • ¼ cup dry (~2/3 cup cooked) rice: 36g
  • 1 medium potato or 1 cup yam: 35g
  • 1 serving (1/6 recipe) red lentil soup: 40g
  • 1 serving (1/6 recipe) millet burgers: 40g
  • 1 serving (¼ recipe) tri-plate: 60g
  • 1 serving (¼ recipe) pesto pasta: 60g
  • 1 serving of Vega Energizer (caffeinated) or Accelerator (non-caffeinated): 15g
  • 1 Vega Sport Endurance bar: 27g
  • 1 serving (2 squares) Power Snack by Navitas: 15g
  • 1 Tbsp honey or maple syrup: 15g
  • 1 cup coconut water: 10g

If you grab a calculator and start adding up the numbers it’s likely you’ll find those carbs don’t add up as fast as you thought they might, in order to hit your ideal number of between 7-10g/kg. It also means in the two-three days leading up to your race, there isn’t much room for concentrated sources of fat and protein… Something to consider.

According to Matt Fitzgerald, author of The New Rules of Marathon and Half-Marathon Nutrition (which, by the way, is a great read for any half or full marathoner), an appropriate sample carb-loading meal plan for a day looks like this: oatmeal with raisons and an OJ/banana smoothie for breakfast; carrots with dip for snack; split pea soup with toast for lunch; energy drink in the afternoon; pasta with tomato sauce and a small salad for dinner; plus an apple to finish off the day.

Note the absence of concentrated sources of fat and protein – if they showed up in the meal plan, the calorie count would be too high overall – and it would probably also feel nearly impossible to eat all the food! While a weight gain of a few pounds in the form of water-weight from carb-loading is to be expected (for every gram of glycogen stored, approximately 3 grams of water are stored alongside it), we don’t want to be gaining any fat from excess calories.

I’m off to grab a banana oat muffin and glass of tart cherry juice. Personally, I’ve never been so well prepared for carb-loadin: granola bars, banana oat muffins, power cookies, granola, hearty rice salad, tri-plate – all prepped, just waiting to be gobbled up.

How will you prepare for your next big race?

Eat clean, run strong, be well… Cheers,


Sarah J Cuff, RHN

Image 18PS. I am thrilled to introduce you to Tracey Lamontagne, who approached me five months ago looking for guidance in how to run stronger, recover more quickly and reach her racing weight. Upon implementing her Eat 2 Run plan, and remaining committed to it… She began seeing the results! Today she feels strong, confident and lean, plus has such good energy and is still amazed at how quickly she recovers from her workouts. Click here to read more about Tracey’s experience with her Eat 2 Run to Race Day program.

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