For thousands of runners preparing for the New York City this Sunday, sitting down to a pasta dinner the night before the race is an essential tradition.
In this age of vilifying carbs, why do runners still embrace them?
Carb-loading predates the running boom; in the ‘60s, a Swedish physiologist discovered that high levels of glycogen help athletes perform better in endurance events. Since then, pasta (which converts to glycogen in the liver and muscles) and runners have been inseparable. And for good reason, sports nutritionists say: loading up on carbs before a marathon really can boost your race-day performance.
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What not every runner knows, however, is that carb-loading involves more than that mound of spaghetti at the pre-race pasta feed. We talked to Patrick Wilson, an assistant professor of Human Movement Sciences at Old Dominion University who has studied the science of carb-loading, and Susan Boegman, head of nutrition for the Canadian Sport Institute, to break it down:
Why it Works Glycogen in your muscles usually gets depleted after about 90 minutes of exercise, leaving marathoners vulnerable to "crashing" or "hitting the wall." By consuming higher-than-usual amounts of carbohydrate (which convert to glycogen, the preferred source of energy for exercise) and resting for 24-36 hours before an event, you can maximize the amount of glycogen in your muscles and liver and prolong or avoid becoming depleted, Boegman says.
"This extra glycogen will help delay fatigue so you can run at a higher intensity for a longer time," she said.
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How To Do It In 2012, Wilson led a study at the University of Minnesota to refine the timing of carb-loading. For years, sports nutritionists had believed proper carb-loading took at least a week of tweaking the diet. But when researchers asked 46 students who were training for a marathon to keep detailed food diaries starting just three days before their event, they found that those who had consumed the most carbs just the day before finished ahead of their non-carb-loaded peers.
Here's the simplest way to do it: Replace some fat and protein with carbs the day before your race; no need to increase calories, Wilson says. Some easily digestible, low-fiber, carbohydrate-rich foods include rice, potatoes, juice and, of course, pasta.
"For those looking for a more ‘numbers driven' recommendation, shoot for 3.5-4.5 grams of carbohydrate per pound of body weight per day," Wilson says. That would equate to 600 grams for a 150-pound athlete.
"This is not the time for dieting," Boegman adds. "Low energy intake means low glycogen storage! Eat until completely satisfied at each meal and snack."
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Who Should Do It Few of the runners in Wilson's study ate enough carbs to impact their performance. But while "carbohydrate loading is something to consider if you're looking to run faster," Wilson notes, "if you're looking to just finish a marathon and plan to walk/jog at some point, you probably don't need to pay extra attention to getting lots of carbohydrate in the days before the race."
And don't expect to set a PR simply by consuming carbs, he adds. The average time benefit is in the range of 1-3 percent for most people.
Also, carb-loading may not work well for athletes who have adopted a low-carb diet, Boegman says.
"This strategy causes the downregulation of enzymes necessary to break down carbohydrates – meaning the extra carbohydrates consumed during a glycogen load are not effectively utilized, and at the end of the race you would be unable to sprint," she said.
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What Not To Do "Ignoring your nutrition and then pounding back a huge meal the night before you race" is not a good idea, Boegman said.
"A huge meal the night before the marathon may leave you feeling bloated and heavy on race day. Instead, plan to increase carbohydrates in snacks and meals throughout the one to two days before and have your big, day before the race meal, at lunch instead of dinner."
The exact timing can vary from person to person, Wilson says, so don't try anything new too close to your race. Don't test out a new breakfast this Sunday, for example, if you're running New York.
It's not too late for runners competing this Sunday to start loading, however.
"I would recommend that the athletes try to start their carbohydrate load as soon as possible so that they are not trying to still ‘load' on the morning of," Boegman said.