Under a blue-black sky lit only by the sliver of a yellow moon, King Jordan wakes Saturday for his morning run at the foot of the Shenandoah mountains.

Jordan, 53, is the president of Gallaudet University in Northeast Washington, and like thousands of middle-aged men in the area, he runs daily. What's different, however, is the lengths he'll go for his runs and the pain he will endure to finish them.

Over the next 24 hours, Jordan will throw up, lose toenails, sweat off up to five pounds of his body weight and limp to the end with painful blisters on his feet.

On this early morning, in addition to his running shoes, cap, T-shirt and shorts, Jordan straps on a fanny pack carefully loaded with water, fruit bars, chocolate, Band-Aids, Vaseline, cotton swabs and other miscellaneous items. Fully stocked, Jordan meets dozens of similarly outfitted runners at 4 a.m. at a white barn on the county fairgrounds. They gather to begin an undertaking that can seem almost cult-like to outsiders, but one they consider simply the ultimate expression of a runner's will. Eighty-eight men and women have come from all over the nation to try to run 100 miles in less than 24 hours in the Old Dominion Endurance Run.

These runners, who range in age from 19 to 66, have paid $125 apiece for this opportunity. They will run over steep hills and rocky trails and through dense forests.

The swiftest will approach a 10-minute-per-mile pace and will finish Saturday evening. The majority will not complete the course until early this morning in utter darkness -- and in utter pain.

"People thinks it's crazy," says Jordan, who is Gallaudet's first deaf president.

"Yesterday at Gallaudet, we were talking about 100 miles. A woman said to me, I have no idea how far that is.' I said, Go from here and run to Baltimore. Then run back. Then you still have about 10 or 15 miles to go.' "

Jordan chuckles, showing a row of white teeth. He joins the others at the starting line. The music from "Chariots of Fire" blares through a hastily constructed public address system, and the runners take off on a half-mile loop of the fairgrounds, then jog through the sleepy town before climbing the first steep, winding trail into the mountains. The remaining stars twinkle, then fade as the sun fights through the clouds in the east.

There will be no prize money, even for the victors, and no national recognition. For their efforts, those who complete the challenge will be rewarded with an Old Dominion Run belt buckle.

Those who win these badges of endurance couldn't be happier. Beyond the Limits

Ultra-marathoning is a rapidly growing sport born in the late 1970s after the initial running boom in the United States. Not satisfied with the standard 26.2-mile marathon, a group of runners founded the Western States 100 in Squaw Valley, Calif., in 1974. The Old Dominion Run was started five years later by Pat Botts, now 57, and her husband, Wayne, now deceased.

"It's a challenge, being able to deal with whatever comes along," says Tom Green, 46, who is attempting to earn his 1,000-mile Old Dominion Run buckle, signifying 10 finishes under 24 hours. "You never know what's going to happen, what's going to go wrong. The way people learn to deal with it -- that's why they keep coming back."

Lots of things can go wrong. Last year, Lisa Smith, a 36-year-old from New Jersey, was leading the women's division when she got lost in the woods and needed 1 1/2 hours to regain her way. She dropped out at the 86-mile mark after urinating blood. Even Pat Botts, who developed the course, fainted one year during a steep, narrow portion of the trail known as Sherman Gap.

That's why even though training matters -- the runners generally average about 40 to 100 miles per week -- experience does, too, which is why 51 of the competitors are 40 years old or older.

Twenty miles into the race, at the first "aid station" -- where runners are permitted to get assistance from their support crews -- James Garcia, 38, a mechanical engineer from Massachusetts, arrives first in 2 hours 40 minutes. Three minutes behind are Dan Barger, 31, of California, and Robert Youngren, 22, of Minnesota.

Aid stations are similar to a pit stop in car racing. Runners grab water, chips, cookies; they change shirts and shoes. They can even sleep if they so desire.

Jordan's wife, Linda, is working as his support crew along with Marcia Montgomery, whose husband, Al, also is competing. The Jordans and Montgomerys are close friends who first met when Marcia worked at Gallaudet. Since Al, 58, took a job as a professor of speech therapy at the University of South Carolina, they keep in touch by meeting at ultra runs across the country.

Jordan ran his first ultra-marathon in 1992 and has competed in 18 -- including six last year. His usual training consists of daily runs at 5 a.m. around the Gallaudet campus with his Dalmatian, Sophie, and the spotted black-and-white running shorts he wears evoke his running companion.

"It's very good for my mental health," Jordan says. "You can be out there with nature. You don't have to be concerned with the pressures of the job -- just enjoy the beauty of nature."

Jordan cruises through the first aid station 3:18 into the race, but stops at the second station at 32 miles for a mandatory medical evaluation. Using sign language -- Jordan lost his hearing following a motorcycle accident 30 years ago and is able both to speak and sign -- he asks Linda for a breakfast snack bar. But she has left them in the car.

As Linda races back to the car, Jordan resumes running, leaving Linda holding a full box of unopened breakfast bars.

"When he came home and told me he was going to do an ultra, it certainly was the next step in the natural progression," Linda says. "You go from 10Ks to marathons to fifties to one-hundreds." She laughs, then says: "Now, the next step might shock me: The Run Across America. I can see it coming."

Linda and Marcia have learned not to question their husbands' passion for ultra-marathoning. Al is so committed that after he had surgery for prostate cancer in August 1994, he ran around the streets with a catheter to train for the Arkansas 100 that October. In fact, Al is running this race despite still recovering from surgery in October 1996 for skin cancer.

Jordan is so committed that five years ago he began running one 26.2-mile marathon a month. At a marathon in Cincinnati, he and Linda arrived only to find that Jordan and the race director were the only participants. Jordan won, and the race director had to stop running in order to present Jordan the trophy.

"It's in the kitchen," Linda says of the trophy. "Every year, the night before the Marine Corps Marathon, we have a spaghetti dinner party with King's running buddies, and we put the trophy right in the middle of the table. How many people can say they won a marathon?" Falling Short

By the 47-mile aid station, at wooded Fort Points Road, runners are beginning to drop out, including Garcia, whose right foot has blistered so badly that he cannot continue, leaving Barger and Youngren to assume the lead.

Jordan reaches that mark around 2 p.m., approximately two hours behind the leaders, and throws up. He continues to have stomach problems until he reaches the 64-mile point at Little Fort Road, where Linda feeds him crackers, which settle his digestive system.

Montgomery is hours behind Jordan, and he drops out of the race at the 47-mile point. Montgomery has never earned a buckle at Old Dominion. He returns to their hotel for a shower, then rejoins Linda and Marcia to help crew for Jordan. "This is the last of the challenges," he says. "I've run under 24 in other races, but not this one. I'll be back till I finish this one under 24."

The final 25 miles of the race are the toughest, beginning with Elizabeth Furance forest, where runners can team with a pacer for 11 treacherous miles. Botts reaches that point suffering from a lack of sodium in her blood, causing her hands and feet to swell. She is taken to Shenandoah Valley Memorial Hospital, where she will spend the night.

At sunset, Barger emerges from the mountains and finishes first in 17:04, an average of 10 minutes 14 seconds per mile. His time is two hours slower than the course record of 15:10 set by Eric Clifton in 1992, but it is a personal record by four hours for Barger.

It is 9:03 p.m. Barger's wife, Lorrie, and about two dozen others greet him with a brief ovation. There is more fanfare at local five-kilometer fun runs. Barger sits down in a lawn chair. He is soaked with sweat and he has three cuts in his right knee, courtesy of a fall he took in the woods. Thirty minutes later, 24-year-old Ian Torrence, who attended Gaithersburg High School, finishes second.

Janice Anderson, 31, is the first female finisher, arriving at 10:25 p.m., for a time of 18:25. She is seventh overall and is followed by Lisa Smith and Martha Swatt, putting three women in the top 10.

It is dark out again now. Jordan is still in the mountains. He has gotten a second wind. At the 86-mile mark at a point known as Veech West, Linda and Marcia break out their traditional ultra-marathoning wine and cheese dinner. One by one, runners pass, many now walking, their flashlights bobbing in the darkness.

Jordan hardly stops at the final aid station, 10 miles from the finish. It is midnight. He has one final hill to climb, followed by a winding descent and a two-mile jog through town.

Finally, at 2 this morning, Jordan arrives for the final lap of the fairgrounds. Al is asleep in the car. Linda and Marcia cheer Jordan across the finish line with a time of 22:10, good for 19th place. His finish is 25 minutes slower than his personal record, but he has earned his fifth Old Dominion Run buckle.

"I think I would like to find a chair," he says, hobbling toward the barn. His legs are caked with mud and his gray hair is wildly disarranged. "I was lucky to finish as fast as I did. I was really sick."

In all, 40 runners complete the course within 24 hours, and 55 finish overall, including 19-year-old Shilajit "Tico" Gangulee, who trudges the final three miles in a driving rainstorm at 10:30 this morning, more than 30 hours after he began.

"Why did I finish?" says Gangulee, who is greeted by two friends and a reporter. "To prove I could do it." And that, as much as anything, is the reason all these runners have finished -- not for awards or recognition, but to show that humans can conquer not just the elements but also their own perceived limitations.

At the awards breakfast today, Jordan is stiff but mobile, which is good because he has a meeting with Gallaudet's President's Council at 9 a.m. sharp Monday. And, of course, by the time the Jordans get home, Sophie will be itching for her morning run.

Jordan considers for a moment.

"Actually," he says, "I think I'll be walking Sophie this time." CAPTION: Gallaudet's King Jordan makes his way through the Old Dominion Endurance Run.