Usually it's the lower limbs that are the first to go, starting at the calves and working up the hamstrings - that weak-kneed sensation that makes you feel as if your legs are made of spaghetti. From there it could be one of any number of things: shortness of breath, dizziness, tunnel vision, and a queasy feeling directly related to failed attempts to suck in oxygen by the metric ton.

Then the mind kicks in, informing the rest of the body that, yes, you do plan to reach the finish line and, no it won't be on a stretcher. Although you later don't remember doing it, you eventually cross the finish line, in dire need of several gallons of Evian and a bed.

The story is familiar to almost anyone who has taken up competitive distance running, whether as a hobby or as a profession (although the professionals would likely claim that, if they did in fact experience such an event, it was so long ago they can't remember it.) Often experienced in a person's first-ever competitive race, it is the result of a poor training program and inexperience in preparing for the first "big race."

"Anyone can run 26 miles - it's not as hard as everyone thinks," says Jeff Reed an Arlington resident who has been running competitively for 15 years. "The hard part is being able to walk the next day. That's the challenge. There is a lot of needless pain when you run a long race and you're not ready for it. It's more enjoyable to run when you're in shape."

Experienced runners and trainers agree there are basically three phases when preparing for the big race": Build- up, intensity, and preparation.

Build-up

The problem with runners entering their first major race, experienced runners say, is that they are not physically prepared. Some runners, thinking they are intrinsically fit enough, give themselves very little time to train. Others over-prepare, running themselves into the ground months ahead of time with the philosophy that by training hard every day, the actual run will not be difficult.

The latter mistake is usually the most common, says Reed, noting that the running mentality of the 1970s - long runs everyday - still exists with newer runners.

"That was the period when overtraining was the thing to do." Reed says. "Now it's easier because it's not popular to do heavy mileage anymore. People have come to realize you don't need that. If you do your usual training and one long run a week, you can do just as well or better because your body is not destroyed."

Rather than aiming for triple-digit miles every week, Dan Rincon, the head cross country coach and assistant track-and-field coach at the University of Maryland, said inexperienced runners must first learn what their bodies are capable of handling.

The best way to do that, he says, is to start the build-up phase early - at least 14 to 16 weeks before medium- size races. For longer runs, such as the Marine Corps Marathon, training should begin as much as a year ahead of time.

With that in mind, runners should first establish some sort of daily training schedule that takes into consideration their jobs, family time, and other responsibilities. Should you run in the morning? At lunch? At night?

With that decided, the next decision is to determine how much to run. "Everyone's a little different," says Rincon, who advises and helps train Jim Hage, one of the area's top runners and two-time winner of the Marine Corps Marathon. "For some people, 15 miles (a day) may be their big run. For others it may be 30."

During the build-up phase, Rincon recommends a daily run of six to eight miles, with a longer run on Sunday. That schedule can deviate, but the longer run should be about 50 percent longer than the daily run.

Reed agrees, but noted that runners should focus not only on the mileage. "It's not a numbers thing," he says. "You have to find out what's right for you. If your body can't handle a lot of miles, you have to adjust."

The weekend runs provide the strong base level of endurance, while the longer runs prepare the body for the extra endurance needed for the race.

Intense Training

This, says George Mason University Track and Field Coach John Cook, is where the real fun begins. And he should know. A native of Germany and former soccer player, Cook has turned GMU into one of the nation's premier track teams. From Rob Muzzio, the two-time NCAA decathlon champion, to Abdi Bile, the world champion in the 1500 meter race, Cook's individual athletes and teams have placed the small Fairfax school on the track-and-field map.

"The name of the game," says Cook, "is fitness."

The build-up phase, says Cook, is the proper technique for aerobic training, that is, allowing the body to maintain the correct oxygen supply while still training. The marathon, he says, is an aerobic exercise because the respiratory and circulatory systems are not strained to the point of depleting the body of needed oxygen. Anaerobic exercising, however, is training when the body is depleted of oxygen. That, of course, means speed training.

Cook's ideal weekly workout is as follows: One day of long interval workouts, consisting of several 1000- or 1600- meter runs. Between each run you should take a 60-second rest. Those runs should equal the same distance as the daily distance runs and should be preceded and followed by longer, easy runs.

Two other days should be set aside for hill workouts. "It's best if you find a continuous hill," although he says they should have gradual slopes, not steep. One of the hill days should focus on shorter runs, while the second should include longer runs. Each run should be done incrementally, with rests in between.

The remaining four days should remain distance days, with the fourth day the longer run. But while the volume should stay the same, the intensity and speed of the runs should increase, he says.

Both Cook and Rincon agree that one of the biggest mistakes distance runners can make is to increase the intensity and speed to the point of stressing and, eventually, injuring the body.

"You can't keep up the large volume and increase the intensity for very long without a breakdown," Rincon says. Runners should therefore keep close eye on body "messages" that tells them to slow it down a notch. As your body is being broken down by the heavier workouts, they say, it must be given the opportunity to naturally mend itself. It is at that point when nagging injuries often occur.

"There are times you know there is absolutely no way you're going to get a run in. You should listen to your body and incorporate some rest. That's an important factor as the body adapts to the harder efforts."

Preparation

The final phase focuses on preparation - both physical and mental.

Starting about 10 to 14 days before the race, rather than increasing tempo, experts say runners should concentrate on resting. Known as "tapering," this time period is used to freshen the legs and build up the body's energy resources. Interval training is completed, and distance runs should be cut in half, with the one long run still maintained.

At the two-week mark, as Reed puts it, "You're either in shape or you're not. You might as well be well- rested."

Rincon says you know you are ready "when you finish your run feeling as if you didn't run enough. That's when you are building your energy up, and that's what you want." The last few days can also be used for mental preparation. Rincon advises runners to know the course ahead of time and create in their minds how they intend to run the race. "It gives you a sense of calm and confidence as you approach the starting line if you've already mentally rehearsed the race in your head."

Rincon knows from where he speaks. A state champion distance runner in high school, he was an All-American while a student at Maryland and was the Atlantic coast conference champion in the 6- mile run, now known as the 10,000-meter run.

In 1980 he recorded the nation's 5th fastest time for 20 kilometers and 8th for 10 miles (47:49). His personal best include a 4:09 mile and a two-hour, 20-minute marathon.

A realist, Reed says that runners just entering competitive running shouldn't expect tremendous results. Instead, they should set their own goals and concentrate on meeting them, rather than attempting to lead the pack. Further, Reed says that no matter how much you train, unless you're the best in the field, there will be a gap separating the good from the best.

Offering his last-minute advice, Rincon says, "If you're a first-time marathoner, give yourself the time to prepare properly. There is nothing worse than not being properly prepared and paying the consequences for it.

FUELING YOUR FOOT-POWER

While for some the actual running may be the hardest part of training for a race, for others the most difficult aspect is deciding which food is safe enough to shovel into their mouths.

The world's perfect diet has yet to be created, but nutritionists have consistently recommended a meal plan that consists heavily of carbohydrates, such as pasta and potatoes (and that doesn't mean pizza and french fries). Fried foods and foods with heavy fat content should be avoided at all costs. "Fat is fat," says Cook. "In a 40-minute workout, you'll burn the hell out of carbohydrates, but you will not have even started on the fat."

Cook says men are capable of burning fat faster than women and can be a bit more lenient. Still, he says women should be limited to 20 to30 grams of fat a day, and men 40 to 50.

And the morning of the race? "Eat whatever your body is used to," says Reed. Before races, he says he munches on a few pieces of bread to keep something in his stomach. After the race: "I eat like a pig."