NEW YORK -- The elevated subway trains clatter by a few blocks from Elmhurst Hospital. Across the street, kids play stickball in a playground where the only grass is that which struggles through the asphalt. From a hospital window, you can look over the midrise apartment buildings and see the Empire State Building in midtown Manhattan, but it may as well be a continent away.

This is where Mark Sobel spent two months. A former walk-on defensive end for the University of Maryland football team, Sobel is now a surgical intern at Mount Sinai Medical Center, although much of this year will be spent at other hospitals in the city.

Now 27, Sobel was not exactly a star when he played football for the Terrapins -- 5-foot-10, 195-pound defensive ends rarely are. He walked onto Jerry Claiborne's 1978 team as a freshman. He never started a game, but he played four years and was a member of the special teams for the 1980 Tangerine Bowl.

"He kept plugging and kept plugging," said Claiborne, who left Maryland for Kentucky after the 1981 season. "He wasn't that talented, but he was a real inspiration."

Sobel graduated from Maryland the following spring and this past spring graduated from Case Western Reserve Medical School in Cleveland. Next July, he will begin four years of orthopedic residency at the prestigious Hospital for Special Surgery in New York. Eventually, he says, he might like to become the physician for a professional sports team, but just as likely, he will work in the orthopedic area known as orthoplasty -- total replacement of joints.

"Last week, walking back from getting pizza, a couple people asked, 'Are you a surgeon?' " said Sobel, who was wearing his surgical scrubs at the time. "It's exciting, but it's not that big a thing. Once you get to that point, there is something else to shoot for. I got my diploma at med school and all these people were congratulating me. But I told my fiance, 'To me the excitement now isn't getting my M.D.; it's orthopedics.' Now, the excitement is working at the Hospital for Special Surgery. What excites me is what I have my sights on next."

As a junior at Matawan (N.J.) Regional High School, Sobel thought he might like to become a physical therapist, but his father, Murray, convinced him that he could be a doctor. So he majored in zoology at Maryland, juggled books and ball, and graduated with a 3.6 grade-point average in his major.

"That was the hardest thing," Sobel said. "Even though I was not an important player, I was very dedicated to playing, so I would stay and lift and work out. I nearly always had an 8 a.m. class. I went to tutors most days of the week. One night it would be in physics, one night chemistry. I'll tell you, it's difficult to cram organic chemistry.

"Football became my social life. Most any extra time had to be for studying. Coach Claiborne was always open to the fact that I needed the tutors and I was always able to pursue my academics with him."

During his junior year, Sobel was at a gathering of football team members, alumni and recruits, where he met Dr. Irv Raffel, an alumnus of Maryland and its dental school. Raffel, a longtime member of the Terrapin Club, was told that Sobel was interested in medicine, and he began to assist him with career guidance.

Raffel has a private practice in the Cleveland area, so he helped Sobel get a job in a research laboratory at Case Western after his graduation from Maryland. During that year, Sobel lived with Raffel's family and took the one course (and got the needed A) he had to have to get into Case medical school.

"Anytime Mark has been given an opportunity," said Raffel, "he's followed through and made the most of it."

Consider, for example, how he met his fiance.

During that first year in Cleveland, Sobel was walking with a date through a mall after seeing a movie. They stopped to browse in a store, and while his date was trying on a blouse, Sobel noticed one of the sales clerk. Another store worker called out her name, Mary Grace, which Sobel stored in his mind. A few days later, he called the store and asked for Mary Grace.

"Are you the one that put the blue dress on hold?" Sobel recalls her saying.

"No," he said, "but how about a cup of coffee?"

Sobel and Mary Grace Massaro, who is scheduled to graduate this year from Youngstown State, became engaged in August and will be married next September.

During his last year of medical school, Sobel spent a month at the Hospital for Special Surgery, another at Harvard and another at Johns Hopkins. They were what amounts to tryouts, and all three later asked Sobel to join their residency program. While at the Hospital for Special Surgery, he met New York Giants physician Russell Warren. While at Harvard, he met Boston Bruins physician Bert Zarins. All Kinds of Cases

Now, Sobel's life is a blur of work and study in the setting of a big-city hospital. The days are long and filled with a variety of cases, and not just your recreational jogger coming in to have a bit of tendinitis treated by the orthopedic department.

Around the corner from Elmhurst, for example, is a pizza place that provided Sobel with an interesting day recently. "One guy had his dog tied up outside," said Sobel. "Another guy dumped beer on the dog and it led to a fight." And that led to a lot of action in the emergency room.

Gunshot and stab wounds, along with motor vehicle accidents, are frequently the reasons people find themselves in the Elmhurst emergency room. Another dilemma doctors and nurses face is the high number of patients often referred to as IVDAs -- intravenous drug abusers -- who have a greater likelihood of having AIDS.

Once you see patients whose ankles are handcuffed to the gurney, it's easier to understand why there are as many police as there are in the emergency room area. The New York Police Department often is represented, as are the hospital security force and the city corrections department. Elmhurst is one of the closest hospitals to the city's main prison on Riker's Island.

Some nights can be wild. Doctors on call can nap in a dormitory room in the building next to the hospital, but they average only a couple of hours a night.

"The worst night is Halloween," said one senior resident. "Every five minutes there's another kid in a costume with a broken arm."

Most of those in the ethnically diverse area are working-class people, although many fall below the poverty line. One woman admitted to the hospital was found to speak only Arabic, which presented a problem.

"They don't like the term melting pot anymore, so I guess you'd call it a mixed salad," said a member of the emergency room staff. 'Lump in My Throat'

The oldest of four boys, Sobel played on the offensive and defensive lines for the Matawan football team, whose coach told him "not to bother" trying out at a school such as Maryland. But he did, and after three years of lifting weights and getting banged up on scout teams, Sobel played enough to earn a letter his senior year under Claiborne.

But a couple of days during his junior season always will stick out. Sobel had played a fair amount during the season, but when the traveling squad for the Tangerine Bowl was announced, his name was not on the list.

"I got a lump in my throat," Sobel said. "But what are you going to do?"

But a petition was circulated among the team, asking Claiborne to include Sobel.

"If there's one memory I'll always have, it was that day," Sobel said. "Coach Claiborne came out and told us to get down on one knee. When he said that, it usually either meant trouble or somebody died. And when he said, 'Men, take off your hats,' we were really worried. But then he said, 'Men, I just want to say one thing: Mark Sobel is making the bowl trip.' That is one memory I will always take from Maryland football. The camaraderie . . . I miss that."

But Sobel left with more than a piece of paper, numerous friendships and a Tangerine Bowl watch that he still wears.

"The discipline, the dedication stayed with me," he said. "To get up at 3 a.m., and being where you have to be, football teaches you that. You don't want to run, but you know you've got to suck it up and do it. That really has helped prepare me for what I have to do now."

In television terms, Elmhurst is closer to St. Elsewhere than General Hospital. A visitor asking a nurse for directions to the clinic was told, "You can walk this way and go down two flights of stairs or you can go that way and wait an hour for the elevator." Most ward rooms have six to eight beds in them. It's possible to get a single room, but if you could afford one, you probably wouldn't be at this hospital, anyway.

If all of this sounds like the medical equivalent of being sent to Siberia, it isn't, at least in Sobel's case. He will get enough of the high-tech, research-oriented atmosphere at the Hospital for Special Surgery. What he wants out of his stay at Elmhurst is the front-line experience.

On one recent night, an unidentified man came in with a broken leg and a skull fracture, the result of an auto accident. Sobel, with a senior resident watching over him, had only 20 minutes to manually reshift the broken leg bone so it was back in place and put a cast on it before the man had to go to the operating room, where a neurosurgeon dealt with the skull fracture.

"It's like being a walk-on," Sobel said. "If you work hard and show you want to do it, you'll get a chance. But, obviously, if you're not qualified, you won't be there."

After observing the neurosurgeon perform the operation on the fractured skull, Sobel and a visitor made one last swing through the orthopedic ward to check on his patients. One of them, an 85-year-old woman who recently had her hip replaced, was feeling a bit down.

"Not so good," she said when Sobel asked how she was doing. "I'm an old lady. Enjoy life while you're young. Can you get me a noose?"

Sobel told her that wasn't the answer.

"If you take time to answer their questions and listen to them, it usually alleviates most of the stress," Sobel said. "Sometimes they like it if you draw them a picture. When you start talking about tibias and fibulas, they don't know what you're talking about. They don't always know what's under the skin. They just know the foot bone is connected to the leg bone.

"You don't want them to think they have to grab you to keep you from running right to the next bed. It's very individual. Some need more time than others. She needed a few more minutes."

Still, there never seems to be enough time. This day started for Sobel at 7 a.m. with the first of three sets of rounds. This one is supervised by a senior resident. Having just switched from orthopedics, Sobel will be assigned patients by her. By 8 a.m., the rounds are over and the group of residents heads to the cafeteria for breakfast. Like most hospitals, the food and drink all look too plain and too healthy. Not nearly enough caffeine, especially for that hour of the day.

After doing some paper work for his new patients, Sobel joins the rest of the group at the outpatient clinic, where about 50 people are waiting when it opens. The wife of an elderly man who had his leg treated by Sobel complained about having to wait all morning and how she didn't want to wait again to get some ointment from the pharmacy. Because Elmhurst is a public hospital, the cost is comparatively low, but it isn't free. That posed a problem for the man who had a bullet go through his thigh. The wound was healing on one side but the other was not doing as well. Sobel suggested he return in a week.

"You're lucky it didn't hit the bone," said Sobel, who can help with the wound but has to defer any financial guidance to the hospital administrators. From 11:45 to almost 1:30, the group of residents and several attending physicians make rounds. They discuss each case and physicians quiz the residents.

At about 5 p.m., an old woman with a bad foot is wheeled into the fourth-floor ward. Sobel is responsible for getting her ready for the next morning's surgery, which means making sure she gets two intravenous solutions that evening.

At 7 p.m., Sobel is pulling out of the parking lot. After dinner, he will study the procedures for the woman's operation. Then he may get a few hours' sleep before he's due back in the morning for the surgery.

The next day, the attending surgeon is in the operating room with Sobel, but mostly he stays out of the way. He would have done it all himself if Sobel hadn't shown beforehand that he had a clear understanding of what was to be done.

"If you show you know the case, they'll give it to you," Sobel said. "But if you don't know exactly where the incision is to be made, exactly where the nerves, blood vessels and everything else are located, they won't give it to you. You have to show you can do it."