To Fuel Or Not During Training
The answer generally depends on duration and conditions of the workout, but teaching your body to rely on fat as a fuel source during long runs can help prevent the depletion of carbohydrates—known as hitting the wall—during endurance events.
“Very rarely do I let my athletes train on a carb source—there has to be a good reason for doing it,” Austin says. She reveals that when Keflezighi, 2009 ING New York City Marathon winner, runs 26 miles at 7,000 feet, he’ll complete the run with only a six-ounce bottle mixed with water and a drink with carbs—and he may only have three to four ounces of it. “He’s trained to do it. He’s taught his body how to use fat as an energy source, so when he gets to the marathon start line, he’s prepared.”
For us mortals, Austin recommends that part of training for the marathon should include teaching the body how to use fat. She recommends going out about twice a month for long runs on very little carbs—have a small amount of low-glycemic food such as toast with cream cheese or oatmeal swirled with peanut butter before the run—but try to get through the workout with only electrolytes and water. Once a month, complete a simulation run, where you practice your in-competition fueling.