Carb Loading for Endurance Athletes

by guest contributor, Dr. Dan Shuman

Carb loadingIt’s race day. As an endurance athlete you’ve undoubtedly put in months of intense training to get you to this moment. All those early morning training sessions are about to pay off, or at least that’s what you’re hoping for. It’s hard to imagine that something so seemingly simple as race nutrition can derail your race-day performance. There is however, strong scientific evidence that demonstrates that nutrition can and will do just that. The intent of this article to provide a game plan in the days leading up to your endurance event that will provide the appropriate nutritional framework so that all you have to worry about is going fast!

The conventional definition of race nutrition, has been to eat a large bowl of pasta the night before a race. While this does offer a rich supply of carbohydrate, this practice may be more based in superstition than hard fact. The body’s preferred fuel source during any sporting activity is glycogen. Glycogen is the stored form of glucose, the most basic of carbohydrate is normally obtained by eating fruits, vegetables, grains and other starches. The body can store glycogen in two areas of the body: the liver and to a greater extent, the muscles. The night-before pasta dinner tops off the stores in the liver but does little in the way of increasing muscle glycogen stores. An endurance event greater than 90 minutes depletes the body of its muscle glycogen stores. This can lead to decreased performance otherwise known as “bonking” and can force you to slow down or stop entirely. Carbohydrate loading, also called glycogen supercompensation, is a technique used to increase muscle glycogen levels prior to an endurance event, which is going to give you the most bang for your buck. There are a couple methods out there to load but some are uncomfortable and produce undesired gastrointestinal side effects. The following is one method that’s proven to work with minimal side effects.

Days before Event
ActivityCarbohydrate Intake*
6 days out90 minutes at 70-75%4 grams of carbs per
kilogram of BW**
4-5 days out40 minutes at 70-75%4 g/kg
2-3 days out20 minutes at 70-75%8g/kg
Day beforeRest8g/kg

* The best source of carbohydrate during this phase should be simple rather than complex. Things like fruit (dried or fresh), juices, Gatorade, rice or potatoes can be good sources.
** BW: Body Weight: An example would be a 175 pound man (approximately 80 kgs) would consume 300 grams 4-6 days out and approximately 600 grams leading up to the race.

Now this may seem like a lot of carbohydrate but this strategy is geared at maximizing performance through the manipulation of nutrition. You are not going to eat like this forever and probably couldn’t even if you tried. Also remember that water is needed to store the glycogen in the muscles. Some endurance athletes complain of feeling bloated and weight gain with this technique but realize that any weight gain leading up to race will be mostly water and you’ll sweat it out during the event. If you do not choose to do a method like this, then you’ll need to have a game day plan that includes some carbohydrate intake before and during the event. The meal before the race itself should be at least 2-3 hours before your event and should be relatively small to minimize gastrointestinal distress, around 200-300 calories with most of it coming from carbohydrates. Do include some protein, which will keep the insulin response from spiking and dropping your blood sugar right before start time; something you definitely do not want. Keep the fiber count low as it can sit in your gut, soak up fluids and cause discomfort. As far as eating during the endurance event, there really isn’t a need for caloric replacement before 60 minutes and it’s generally recommended to intake 30-60 grams of carbohydrate for every hour of endurance exercise. Sports drinks are optimal but gel packets (or even honey) with water are a good substitute. Aside from nutrition, be sure your hydration levels stay adequate with about 16-24 ounces of water per hour of exercise depending on the body size, sweat rate and the outside temperature.

Please realize that above program is merely one approach that is out there. It’s an attempt to try and maximize race-day performance. If you’ve been having success with a methodology of your own, stick with what works for you. If you’re ready for something new, give this program a try and see for yourself the results you can achieve.




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