By the time 11,000 runners take their marks for the Marine Corps Marathon Sunday, Lt. Cmdr. Peter Mendel and his medical team of 300 will be set.

And for good reason. One runner died during last year's marathon, and about 5 percent of the runners needed some sort of medical treatment. Blisters were the biggest problem, but if there's a body part that can be pulled, strained or twisted, someone is bound to do it along the 26-mile odyssey. Not to mention cases of nausea, cramps and chest pain common to any race of this magnitude.

Commonly called the "People's Race", the third-largest marathon in the United States lines up plumbers, accountants, engineers, dentists, carpenters, hair stylists, real estate agents and teachers, along with the nation's military ranks, and gives them a chance to lift their feet 41,920 times.

Mendel, a family physician with a interest in sports medicine, volunteered to be the medical coordinator after working in two previous marathons. On Sunday, the medical team will muster at 5:30 a.m. at Quantico. By race time, 9 a.m., Mendel's troops will be deployed to their strategically positioned duty stations along the course.

Navy doctors, nurses, physician's assistants, corpsmen and other medical volunteers will work inside olive-drab tents erected by Marine Maintenance units. There will be eight medical aid stations and two complete field hospitals: "Primary MED" at the finish line near the Iwo Jima Memorial and "MED Alpha" near mile 21 on Hains Point. In addition, 23 emergency vehicles will be stationed along the route.

Aid stations are set up to provide immediate first aid for minor and major problems, while the field hospitals are prepared to provide sophisticated, specialized care.

"It's the in-depth medical care of the Marine Corps Marathon that sets it above other races," says orthopedic surgeon David Brody. Now in private practice in Connecticut, Brody became involved with the marathon nine years ago. An avid marathoner with expertise in sports medicine, Brody was on the staff at George Washington University Hospital at that time.

The Marines worked with Brody's civilian medical volunteers to establish a network of personnel trained to handle the potential problems of marathoners. Five years ago, when the Navy took over medical support, "they not only maintained the principle of immediate specialized care," said Brody, "but dramatically increased the capability to treat larger numbers.

"The military is perfect for a marathon," Brody adds. "They're trained to work in the field and to respond quickly."

The 23 emergency medical vehicles include eight ambulances from D.C. area rescue squads and the American Red Cross. Not just for transportation, the vehicles are sophisticated mobile medical units.

Eight of the ambulances are equipped with advanced cardiac life support (ACLS). Using this technology, on-board medical personnel have the capability to respond to a cardiac emergency with defibrillation (electrical shock to the heart) and cardiac resuscitative drugs. Like any Marine maneuver, communication between units is vital. From his command post at Primary MED, Mendel will be in direct contact not only with the aid stations, MED ALPHA and emergency vehicles but also with six area hospitals available to receive patients. There is even a U.S. Park Police helicopter available for evacuation.

The Marines never wanted to find out exactly how quickly medical units could respond to an extreme emergency. But last year, they had the test when 32-year-old Marine Staff Sgt. Martin Wurst Jr. collapsed near the Washington Monument.

Medical response was immediate. Within seconds, a Marine began to administer CPR. With incredible luck, Richmond cardiologist Robert Rea, who was running in the marathon, took over about two minutes later.

Within five minutes, an ACLS team arrived and began the same sophisticated measures that would have been used in a hospital emergency room. (Guidelines of the American Heart Association state that cardiac emergencies should be given CPR within four minutes of collapse and advanced resuscitative measures within eight minutes.)

Despite the rapid response, Wurst, who had asymptomatic advanced coronary artery disease, was pronounced dead after arriving at George Washington University Hospital.

Sudden death during a marathon, although a reality, is rare. More common are dangers caused by dehydration and overheating.

"The human body is extremely sensitive to changes in body temperature," says Mendel. If a runner doesn't drink enough water, body temperature can go too high (hyperthermia) and affect respiratory and cardiac functioning. Symptoms of hyperthermia include unsteadiness, nausea, labored breathing and muscle cramps.

Navy medical workers like Hospitalman 2C Lois Rangel are trained to carefully watch for runners in trouble. This year will be her third at MED ALPHA field hospital.

"If I see someone wobbling a little or showing signs of distress, I'll ask if they're O.K. or maybe run along with them," she said. "Most runners are smart enough to know when they're in trouble."

Would a runner, thought to be having serious medical problems, be pulled from the race? Mendel says the situation has never arisen and would be a subjective decision based on the situation.

In fact, over half of the marathoners requiring medical aid are treated after crossing the finish line.

Pat Neary of Springfield had an insider's view of Primary MED the year he was pushing to qualify for the Boston Marathon. After holding his competitive pace up and around the Iwo Jima Memorial and under the finish banner, he "wasn't feeling too good."

Helped to the roped-off entrance into the medical area, Neary was "triaged" -- assigned to a particular kind of treatment -- and guided into one of the four tents. Primary MED has one unit for orthopedics, one for podiatry and two for medical problems such as nausea, shortness of breath and abdominal pains.

A nurse took his vital signs and a physician examined him. With a diagnosis of "heat stress," an i.v. was started. Recovering quickly and able to head home with his son an hour later, Neary describes his care as "highly professional and incredibly personal."Although the Marines carefully plan for medical emergencies, preventing problems is the mission of race coordinator Capt. Joe Rovira. "Our goal is a safe marathon, and everthing we do is geared toward that goal."

Working from an Operations Manual that measures almost an inch thick and the experience of coordinating the two previous marathons, Rovira's two primary concerns are an accurate, well-marked course and plentiful water.

Several years back, the Marines ran out of water for runners. Although the dry year was well before Rovira's time, he still says, "That's a marathon nightmare and should never have happened."

This year, there will be 22,000 gallons of water and 710,000 cups distributed over 14 water stations (five more than last year).

During the 12-year evolution of the marathon, several routes have been used. The current course is officially measured and sanctioned by The Athletic Congress (TAC). Runners can use the marathon to qualify for other races, such as the Boston Marathon and the Olympic trials.

Because the Marines do not offer cash prizes to winners, elite runners seldom enter. But with the potential to qualify for the Olympic trials, this year may see some high-level competition.

"Pushing for time puts a runner closer to the edge of injury," says Navy Capt. Jerry Clark of Alexandria. An accomplished master's class runner, Clark coaches and advises several of the D.C. area's top women runners. "This year, the need for good medical support is more critical than ever."

Who is at risk of injury in a marathon?

"Everyone," says Mendel. Participants are encouraged to have a pre-race physical and are given tips on safe running. Brody conducts a series of clinics on the prevention and treatment of injuries.

Both Mendel and Brody point out that if a runner trains adequately for a marathon and takes on enough fluids before and during the race, most starters will finish.

The earned reputation for organization and quality medical care makes the Marine Corps Marathon popular with first-time marathoners. Why?

"It's the Marines," says runner Barb Fitz of Alexandria. "They make everyone feel like a winner."Paula Potts is a free-lance writer in Alexandria. Friday in the Sports section: A complete guide to the marathon.