The Amgen Tour of California kicked off earlier this week and fans across the state are excited to cheer on the cyclists.

Most people participate in the Amgen race as spectators, gawking at the super women and men zipping by on two wheels. While it's easy to enjoy the race from the sidelines, athletes spend months preparing for a race through meticulous training and dieting.

Fuel is a crucial part of gaining endurance for a race and some athletes practice carbohydrate-loading-- also known as carbo-loading.

What is carbo-loading?

It's a lot like it sounds like. Endurance athletes, such as runners, load up on carbs such as pasta, rice, bread, potatoes or other high-carb foods before a big event, such as a half marathon or marathon. Carbs are stored as glycogen in your muscles and liver, according to Runner's World.

Glycogen is the body's most accessible form of energy. During a marathon or race, a body burns through glycogen and fat. When your body runs out of glycogen during a race, it hits a 'wall' and needs to refuel to keep going.

The idea behind carbo-loading is to up the amount of glycogen stored in the muscles to help the body go longer without refueling in a race. Typically, carbo-loading is only done before a high-intensity, long endurance performance.

Does carbo-loading work for professional cyclists?

This year, the Amgen Tour of California covers a span of 645 miles of roadways, highways, and coastlines during seven stages over the course of nearly a week. Participating cyclists are riding for more than three or four hours a day, covering over a hundred miles.

The intensity of the sport results in burning more than 5,000 calories a day during a competitive race, according to Dr. Liz Applegate, director of sports nutrition at UC Davis.

In this case, carbo-loading preparation doesn't help because an athlete isn't just storing for a one-time event such as a marathon. The Amgen race requires an ongoing demand for energy, day after day, Applegate explained.

"They're just trying to survive," Applegate said.

Instead of storing carbs pre-race, cyclists eat as they ride and virtually all products consumed have carbs, said Applegate.

For example, if you're going on a road trip, you prepare to reach your destination by filling up with a tank of gas, explained Applegate.

However, if the road trip is set for many days, the driver needs to keep filling up with gas to keep the car going. No matter how full the gas tank was at the start of the journey, it will need to be refueled for a long trip.

The same idea goes for cyclists. Carbo-loading won't get them through the long haul because of the amount of energy used in the distance covered.

"These cyclists are carb-burning machines and they have to make sure they replenish their stores and are ready to go the next day," Applegate said.

Yes, there is a right and wrong way to carbo-load.

Athletes don't just "pig out" on pasta, according to Applegate.

The process is more organized and planned than just binging on any given amount of heavy carbs.

Many professional cyclists work with a nutrition board and manager who help them strategically come up with the right diet plan before a race, Applegate said.

Cyclists shouldn't stuff themselves before a race.

According to Runner's World, you can't fill your muscles with glycogen in one day. Athletes should start feeding their muscles two or three days before a race.

What's the verdict?

While carbo-loading does work for some athletes, it's not ideal for a professional cyclist. This claim is not verified.

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Dr. Liz Applegate, Director of Sports Nutrition at UC Davis

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READ: 'The Right Way to Carbo-load Before a Race', Runner's World