Understanding Carb Loading

There has been much written in the past few years about the merits of fat, the evils of carbohydrates, and vice versa.  The opinions of coaches, athletes, physicians, and scientists are all hotly debated in various forms of media, although most of that debate focuses on the day-to-day diets of athletes.  It is almost universally accepted that ensuring a full tank of glycogen before a race will only help performance.  (Glycogen is the fuel used by muscles when working at higher intensity.  It is basically stored carbohydrate.)  The argument for some is that “fat adapted” athletes will be able to function longer on less carbohydrate, thereby delaying the emptying of the glycogen tank.  That is a different topic than what we’ll address in this article, but it’s not without its relevance.  While that “fuel efficiency” is certainly important, few would argue the benefit of starting with a full tank.

The idea of carbohydrate loading goes back many decades.  In it’s truest form, an athlete will spend a few days performing very high-intensity training on a low-carb diet.  This depletes the glycogen stores in the muscles and liver.  Following that period, they will then eat a high-carb diet while resting for a few days before their event.  This has been shown to increase glycogen stores by nearly 100% over their normal levels.  Some studies have even suggested that the initial depletion phase is unnecessary.  You’ll notice though, that this is a very different protocol than simply showing up for a big plate of pasta on the night before the race.

While carb loading can be effective, it may not be necessary.  Many 10K runs, shorter triathlons, and half-marathons now have pasta dinners the night before.  If your event is going to take less than 90-120 minutes, you don’t need to be worried about carbohydrate loading.  You will not burn through your glycogen stores in that amount of time, especially if you’ve done any type of taper in the days before the event.

There is a downside to carb loading as well.  In it’s common form (a meal or two of very high carbohydrate foods), it can wreak havoc on your digestion and even lead to mild dehydration.  If you suddenly add large amounts of processed carbohydrates, fibers, and acids (tomato sauce) to your gut, you’ll have some pretty serious distress.  This  can lead to bloating and diarrhea, which is hardly what you want before a race.  Ever wonder why those Port-a-potties are in such high demand on race morning?

You can take some principles of carbohydrate loading and implement them to your benefit though.  Here are some tips and considerations:

• If you have adopted a higher fat diet, you can still benefit from a full tank of glycogen.  At high intensities, carbohydrates will still be your fuel of choice.  In the days before a race, increase your carbohydrate intake moderately while you decrease your workload.
• If you decide that your event warrants a carbohydrate loading period, opt for simple carbohydrates that are low in fiber content.  Choose honey, bananas, skinless baked potatoes, or toast over high-fiber fruits like apples.  You’ll also want to limit your fat and protein intake.  The idea is to make digestion simple and limit potential bloating.  You’ll do this over three to four days, not hours.
• Remember that the vast majority of races will not need a dedicated carbohydrate load.  Take an honest look at your event, your training, and your diet leading into the event.  Unless you will be going for longer than 2 hours (or at a high intensity for longer than 90 minutes), continuing your normal, healthy diet while you taper is best.
• Opting for a pre-race carbohydrate load at dinner and breakfast is likely to be more problematic than helpful.  Too many athletes use the hours before a race as license to eat whatever they want, figuring they’ll burn it off.  Frankly, that’s a terrible strategy!

Your training has been measured and planned for weeks, if not months.  The attention to dietary preparation should be just as rigorous.  In the same way that you have a planned purpose for each workout, your meals should serve to further those goals.  After you cross the finish line, indulge!  But don’t fall victim to the pre-race pasta dinner.  You’ve worked too hard for that.