Steeped in history and mythologized down through the ages, the marathon has enjoyed an intense appeal in this country ever since Frank Shorter raced through the streets of Munich to an Olympic gold medal in 1972. He was the Pied Piper who pulled sedentary Americans out of their easy chairs and sent them running down city streets and country roads.

"It's such a great distance -- the allure, the mystique, the excitement of an adventure -- that you want to achieve it," said Fred Lebow, organizer of the New York City Marathon.

That allure will continue and -- both the medical and running communities appear to agree -- logically should continue despite two deaths within a three-week period in Washington-area distance races that shocked observers and seemed to contradict the norm.

Interviews with doctors and running/exercise authorities following the deaths of a 19-year-old woman in the Marine Corps Marathon eight days ago and a 31-year-old Alexandria man in the Army 10 Miler last month suggest that:Fatalities in distance races are very rare.It is most difficult to discover in advance which individuals may be at greater risk.No one should decide against taking part in a marathon based on the recent deaths.Decisions concerning medical precautions and training preparations rest with the individual -- and individuals should heed warning signs, be practical and take a common-sense approach.Event sponsors appear to do virtually everything they can to cope with crises.

"Exercise doesn't kill a normal heart -- period," said Paul D. Thompson, a cardiologist at Brown University and Miriam Hospital in Providence, R.I.

"What kills {distance runners} usually, in adults over 35, is a narrowing of the arteries because of cholesterol. In younger people, it's usually a congenital defect.

"Since the death rate is low," Thompson added, "it's fairly difficult to prevent."

In a study he took part in, which appeared in the Journal of the American Medical Association, Thompson and some colleagues found that among men ages 30 to 64 in the state of Rhode Island from 1975 through 1980 the "incidence of death during jogging was one death per year for every 7,620 joggers."

Thompson said that about half the victims had known they had "diagnosed heart disease" -- they knew they had some problem. On that basis, he said, "the death rate for healthy joggers is about one for 15,200 per year. You {might} have to test 15,199 {before you got to} the one."

Kenneth Cooper, once an Air Force physician and later founder of the Aerobics Center in Dallas, further attested to the rarity of death during exercise. Cooper noted that few marathon-related deaths have occurred over the years. Moreover, in 19 years at his center, he said, records showed that during almost 9 million miles of people running -- plus cycling and swimming -- there has been only one fatality. And had every participant submitted records, the statistics would have been even better.

The rarity of a heart attack during a marathon heightened interest in the death of Lisa B. Christensen, the Boston University sophomore who collapsed during the recent Marine Corps Marathon. According to her father, Christensen had no history of a heart problem. Tests, including a stress test, might not have revealed the birth defect that led to her fatal heart attack, according to doctors.

The medical examiner who performed an autopsy on Christensen said she had "an abnormal origin of the left main coronary artery" resulting in reduced blood flow to the heart muscle. "The exertion of marathon running may have been a contributing factor," Dr. James Beyer told the Associated Press.

The most thorough test for heart problems, many doctors say, is a cardiac catheterization, but they add that such a procedure involves some risk and is expensive -- $2,000 to $2,500. The bottom-line question about getting such a test, they say, is: Why would anybody, especially a young person, without any sign of a problem get such a test?

"You'd have to have some symptom of discomfort or some other clue," said Samuel M. Fox, a cardiologist and professor of medicine at Georgetown University. "No system has been devised to turn up the rare few."

Someone like Christensen, Fox said, to consider being tested at all would either have had to have a symptom or not be able to perform in the manner she had expected. Even extensive tests, he said, might not have showed such a defect as hers. As for cardiac catheterization, there simply was no reason for her to consider it even if she knew it existed. "She was not a candidate for an exercise test," Fox said.

Fox said that at Georgetown, the university's basketball players are given "echo" studies because of the possibility of Marfan's syndrome in tall individuals. But he said such studies are not given to the school's track and cross-country runners.

Speaking of cases like Christensen's, Barry Maron, a cardiologist at the National Institutes of Health, called these "rare anomalies, the kind of anomaly that kind of falls between the cracks." He pointed out that detection of such defects through "non-invasive" techniques is "possible but difficult."

Because of the specific causes almost always associated with sudden death in marathons, doctors agree that a fatality is not a logical reason for someone else to arbitrarily give up the sport. "The decision not to run shouldn't be based on such an experience," Thompson said.

"As one who supports the concept of a physically active lifestyle, I'm not going to say you should stop because of something like this," Fox said. "It's an individual judgment."

But should, say, a 35-40-year-old marathoner consider additional precautions?

"It's always difficult to make a blanket statement," said Maron, noting that deaths among that age group usually are from coronary disease. "For the mid-life athlete . . . it might be wise to be screened by a cardiologist -- but you have to stop short of saying it's a requirement."

He too used the phrase "individual judgment."

Fox said: "The adage 'Listen to your body' is still worth a lot. You should pay attention to it."

Cooper added that he requires regular stress tests for those 40 and over who belong to his aerobics center. His writings in recent years have "emphasized the importance of moderation" and stressed the "differentiation between health and fitness."

"There's a big difference between health and fitness," he said. "Jim Fixx was fit but not healthy."

Cooper said he urged author-distance runner Fixx to take a stress test when he visited the aerobics center just months before his death in 1984 but that Fixx declined.

Autopsies often show that victims had severe coronary artery disease that had been undetected. Arteries that supply the heart muscle were so narrowed that the heart was deprived of blood and oxygen.

Often people ignore warning signs or don't pick up on them, according to Thompson. "Most people think of chest pains, but the first sign is usually some other sign of discomfort such as tightness in the chest."

In 15 runnings of the Marine Corps Marathon, congenital heart defects are blamed for two deaths, one in 1986 and the one this year. In the 1984 New York City Marathon, a 44-year-old Frenchman had a heart attack and died 15 miles into the race on the event's hottest day ever, organizer Lebow said.

In these cases and others in marathons, including Los Angeles last year when a man in the advanced stages of diabetes insisted on running the distance against his physician's recommendations and died at 18 miles, runners have died because of pre-existing conditions, not from lack of preparation. An athlete will not die from insufficient preparation for a distance race. The body will shut down first: depleted glycogen stores in the muscles will cause the legs to give way or the runner will black out, but dying won't be the body's first response.

"The chance of danger in a marathon, if people are properly prepared, is so minimal," said Bill Burke of the Los Angeles Marathon. "There are no more deaths in a marathon than in any event where 20,000 people participate at any level."

Fundamentally, preparation for a marathon is not outstandingly complicated and consists predominantly of gradually increasing mileage. But a body's response is often unpredictable and despite adequate training and preparation, mishaps do occur. Race-induced injuries can happen to anyone.

Record-setting Alberto Salazar, at his peak, became dehydrated in one race and passed out in another. The 1975 Soviet marathon champion blacked out briefly in the 1990 Marine Corps Marathon. Both men had extensive knowledge about training and hydration. Grete Waitz and Ingrid Kristiansen, the decade's top women marathoners, have dropped out of races because of leg cramps. Cramps occur for a number of reasons, primary of which is lack of fluids and necessary enzymes in the muscles.

On race day, medical personnel deal mostly with musculo-skeletal injuries that "just come with the territory -- running or exposure -- of putting your body through a race of that length," said Cmdr. Robert Schultz, medical coordinator for the Marine Corps Marathon. Last year at the Marine race, Schultz said his medical corps treated approximately 400 injuries, half of which were minor, race-induced, mostly superficial aches and pains: blisters, sprained ankles, twisted knees, dehydration, hypothermia or hyperthermia. The other half involved aggravated previous medical conditions such as asthma.

At the Marine Corps run, probably more than at other races, many of the problems occur with first-time marathoners.

"We're prepared to deal with a bigger spectrum of runners than, say, Boston," said Lt. Col. John Shaw, a doctor at Aid Station 8 at Mile 22 of the Marine Corps Marathon. "We're prepared for a broad spectrum of runners."

In New York, the death six years ago "shook us up," said Lebow, who once ran the Marine Corps race and praises its manpower and preparedness. New York organizers added water stations and increased medical care following the incident there.

"We weren't really well prepared the first 16-17 years but we went into high-gear preparations in 1985 after the death," said Lebow.

As a matter of practice now, most race directors routinely mail out information on training techniques, proper eating and drinking, and weather concerns. They also hold free clinics outlining information about the race course, how often a runner should drink, what a runner should wear, and typical workouts for preparation. The Marines are also set up for minute-to-minute changes. When the weather inched into the mid-seventies a couple of hours after the start, the Marines added to the water supply along the course and increased IVs to the medical tents. Ambulances and medical people roamed the course. The Marines are also one of the few marathons with fully stocked field hospitals at each aid station.

Lebow recalled that in the Berlin marathon this year, a man died 50 yards from the start.

"Death hits people at a certain time and place and you can't always predict it," he said. "Yet you have to remember that there is a marathon in every city in the world, in every nook and cranny, {figuratively at} the North and South Pole. There are lots of runners, pressures, conditions and, annually, there are several thousand marathons and only one or two deaths."

Making the entire 26-plus miles is the professed goal of most participants in any marathon. So it is often more of a struggle for medical personnel to convince runners who are in need of care to stop than it is for the runner to complete the race.

"A lot of them fight you. They know if you pull their bar code off {the race number} they're done and they don't like it, they've come so far," said volunteer reserve nurse Lori Wilson at Aid Station 8.

Doing a marathon entails making it to the finish line, any way possible. Once on their way, runners will walk, stop and sit, lie down for a while -- anything to enhance their chances of eventually crossing that line. Lebow, who has run 21 marathons himself, insists runners do not compulsively ignore their bodies' signals in favor of reaching their goal.

"You know you should stop even if it's not important," he said. "And they do stop. I got letters after the last one saying 'Thank you for warning me, at 19 miles I felt woozy' and the runner was attended to by a medical person and dropped out or continued shortly after."

Jeff Darman, a Washington-based race organizer, took up road racing in 1971, returning to the sport he competed in during high school. He wanted to lose weight. He ran his first marathon within about six months, qualifying for Boston and running it two months later.

"In those days running a marathon was the ultimate achievement," he said. "If you were going to be a distance runner, running a marathon was proof that you really were. At a cocktail party, when you said you ran marathons, it's not like half the room did too. The masses hadn't taken it up yet."

Officials estimate that in one year, nowadays, worldwide at least a million people run the marathon. It is one of the few sporting events the novice and the elite can venture at the same time -- if not in the same time.

"You can't play football with the stars but running is unique because you can," said Darman. "You can be on the same road with the best in the world and you can say you did the same thing. That's one of its fascinations -- there's a mutual respect among marathoners, we all played the same game."

It is an irony of the sport that many of those in the rear approach the marathon with less trepidation than those who win. Many, like Darman, run their first marathon shortly after taking up jogging for health.

"So many elite athletes wait longer to do one than most first-timers," he said. "The elite athletes treat the marathon with much more respect than the average runner. The marathon isn't bad, it just needs more respect. You just have to be careful."