For dinner Saturday night, Steve Schenck said, he will probably sit down to a plate of spaghetti, for the familiarity. Jake Matthews was leaning toward chicken and potatoes, for the "power." Beth Bourne said she might eat some chicken or fish, for the lean protein.

Come Sunday morning, though, before the three local runners join thousands of others on the course of the California International Marathon, Bourne, 41, of Davis, will turn to her trusted plain bagel and banana with decaffeinated black tea – a routine formed over about 12 years of distance running.

"What I've found is I really have to eliminate or reduce all fiber," said Bourne, adding that she usually starts a morning with whole-wheat toast. "Once you've run enough marathons, I think you start to feel like if something worked well, you want to keep doing it that same way."

The exact ratio of nutrient-rich carbohydrates to protein consumed before the 29th annual CIM probably won't be what separates the leaders from the pack. But Olympic- and personal- record hopefuls alike will be burning through glycogen stores that have been built up during training and, like a fuel tank, should be topped off before the starting gun, sports nutritionists said.

Pre-race meals that clash with the gastrointestinal tract can make for an uncomfortable 26.2 miles. And not having enough in the tank can cause you to hit the wall. So whether to top off in the morning, for example, with the carbohydrates from a bagel and fruit or a bowl of oatmeal is a matter of figuring out what agrees with the individual, nutritionists said.

Ideally, those running in the Folsom-to-Sacramento event Sunday already have used their long training runs to get comfortable with certain pre-run foods, said Mary Coordt, a four-time Olympic Marathon Trials qualifier who holds a master's in nutrition from UC Davis.

Going into the marathon, Coordt said, the best thing a runner can do is stick with that familiar regimen. "The week before, you don't buy a new pair of shoes," she said.

"Someone may eat oatmeal (the morning of a marathon); for others oatmeal doesn't work," Coordt said. "A banana doesn't work, but you'll do toast with jam. Basically, all those foods have similar composition, it's just some people react differently. It's about practicing."

Matthews is running his first marathon at CIM. He said he will probably eat chicken the night before, partly because he did so the night before the Clarksburg half-marathon several weeks ago and finished in 1 hour, 13 minutes, 51 seconds.

"Seemed to work all right," said Matthews, 23, of Folsom, a former cross country and track and field athlete at UCLA. "So I'll probably stick with it."

The night before the event, Coordt suggested, eat an early meal "focusing on carbohydrate but not going overboard." The carbohydrates go toward those precious stores of glycogen – carbohydrates stored in the liver and muscles that are pumped through the body during exercise. For most people running the marathon, Coordt said, 80 percent of the calories being burned will come from glycogen.

That, Coordt said, is why it's also important to eat in the morning, two to three hours before the marathon, and "top off those glycogen tanks." Stores are low in the morning due to energy being used overnight to feed the brain and nervous system, she said.

"Would you drive from here to L.A. with a half a tank of gas? No," Coordt said. "So do you want to go do (the marathon), or do you want to add a little to your tanks?"

Schenck, 28, of Sacramento, said he tried to run his first CIM in 2008 without eating that morning.

"My vision started going after mile 20," he said. "Every 30 seconds or so it went entirely black." He finished, but now he munches on a pre-event granola bar.

After a meal high in carbohydrates – a bagel with jam and a piece of fruit, cooked rice with honey – you typically have enough glycogen to last for two to three hours of running, said Liz Applegate, director of sports nutrition at UC Davis.

For the elite runners who have built up glycogen stores over years of high- intensity training and competition, that may be almost enough to last through the 26.2 miles. Some rely only on fluids to carry them through the race.

But for those with an estimated finishing time of, say, 4 hours, 30 minutes, the original stores may not be enough. And if your energy stores become depleted, you run the risk of "bonking," which is running slang for a sudden onset of fatigue.

"When you've gone through the stores, it's almost like your pants are down, you're stuck," Applegate said. "You're just flat out of steam and you have to go to a walk, because you don't have any carbohydrate to do more intense exercise."

Running is a "deficit sport," said nutritionist Sunny Blende – you cannot take in as many calories while running as you burn, which is an average of about 100 calories per mile. But those who can ingest at least some calories stand a chance of delaying the "bonk." At that point, you're looking for simple carbohydrates in the form of glucose or maltodextrin, which go straight to muscles.

Many runners opt for relatively easy-to-consume gel packets along with a sports drink to "keep stoking the fire," Blende said.

Bourne, the Davis marathoner, said she takes four or five 100-calorie energy gel packets during a marathon, one every 40 minutes, trying to find the plainest flavors available. "I don't want to, but I know I'm going through the calories," she said. "I'm trying to break (three hours) and every second counts."

Coordt said that for some experienced athletes, the perception of fatigue may actually come before the full depletion of glycogen stores.

"By taking a little bit of glucose during the event, they give a little power to the brain, so to speak," she said.

As for hydration, marathoners should aim to consume 4 ounces of fluid every 15 to 20 minutes, drinking in sips to avoid stitches, said Ale Lauth, senior health educator at Kaiser Permanente in Folsom.

Lauth, a distance runner herself, said she hand- carries bottles in order to have a constant supply, ever since a bad experience at the 2005 Chicago Marathon in which she hit the wall at mile 23 due in part to dehydration.

Post-race, she said, it's important to drink 20 to 30 ounces of fluid within 30 to 45 minutes, likely a recovery drink with electrolytes and potassium. She said the next meal time is up to the individual – "Personally, I can go a long time after the race without eating anything," Lauth said. "My stomach is just not hungry" – but carbohydrates and protein will help replenish the body's glycogen stores and rebuild battered muscles.

Nutritionists warned against overeating right before the marathon, against ingesting a lot of fiber (to avoid frequent pit stops) and – surprise – against drinking too much alcohol the night before.

For those CIM participants who have developed an eating plan from experience in training, said Applegate, the UC Davis nutritionist, there is probably no need to deviate.

"There's always people out there looking for something different or better," said Applegate. "You've been doing OK. Trust yourself."

* 29th annual California International Marathon

When: Sunday beginning at 7 a.m.

Where: The 26.2-mile course starts at Folsom- Auburn Road near Folsom Dam in Folsom and ends at the state Capitol in downtown Sacramento.

Cost: Free for spectators

More information: For key spectator locations, parking locations, race-day road closures and more, visit the event website at www.runcim.org.

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