But many runners think they have to deplete their carbs before they start overloading on more carbs. That simply isn't true—just increase your carb intake for two days before your marathon.
In fact, British researchers found that a tiny fraction of the 250 runners they followed at the London Marathon consumed enough carbohydrates before the race—and those that did ran about 13 percent faster.
To get you fueled adequately, consume about 7 to 10 grams of carbohydrate for every 2.2 pounds that you weigh, or 475 grams per day for a 150-pound runner. This is a huge number of carbs, so you'll need to include carbs in every meal, and snack often. You may also find it helpful to drink fluid that contains carbohydrates like juice or sports drinks.
More: A Smarter Way to Carbo-Load
Follow this strategy for two days before your race and you'll prime yourself for a much better performance. Only 12 percent of runners in the study in London ate enough carbs before their marathon, so it's possible that you're not, either.
More: An Overview of Energy Sources
How to Run Your Fastest Marathon
Are you a marathoner who wants to run faster, or maybe even obtain the elusive goal of qualifying for Boston?
You don't have to be the fastest runner in the field to run a great marathon. Matt took over 100 minutes off his marathon PR (not a typo), and qualified for Boston. He ran his first race in 4:53, but then learned five key lessons to run almost two hours faster.
The Boston Qualifying Blueprint will show you how you can apply these same lessons to run a faster marathon, and maybe even get to Boston.
More: 7 Tips to Qualify for the Boston Marathon
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