Twenty-four laps around the P.S. 102 gym in East Harlem add up to a mile. Physical education teacher Steven Sloan makes his fifth graders run 25 laps.

“You tell ‘em to jog,” Sloan says, “and they just want to run, fast. They like to run all out.”

His regimen, which he admits is tough, has led P.S. 102 to the top ranks of New York Road Runners’ Mighty Milers youth program. Its 300-plus students together ran more than 50,000 miles last year.

“Here at P.S. 102, the kids really very quickly build up to where they are running a mile and sometimes more than a mile a day,” says Cliff Sperber, executive director of youth programs at New York Road Runners, at a recent event honoring the students. “It’s very impressive.”

In class, Sloan, 55, calls his students by pet names, like “Puff Cheeks,” “Muhammad Ali,” “Vanilla Smoothie” and “Hot Salsa.” He has his stars, the natural athletes who have come to love running under his tutelage. But just as important to him are the ones who come along when it’s not so easy.

Gloria Cruz, “Puff Cheeks,” counts herself among the latter; like many youth in East Harlem, she has asthma. In 2008, the disease sent 11 of every 1,000 neighborhood children to hospitals; in August, the city health department opened a youth asthma center aimed at halving that number.

The demands of gym class helped Gloria get healthier and more fit. Her homework, like her classmates’, is to run a mile a day, seven days a week. Regular instruction from Sloan has also helped Gloria and her mother manage her condition better, leading to fewer hospital visits.

For Gloria and her mother, Maria Santana, weekend walks from their Manhattan Avenue apartment to the school on Second Avenue used to take an hour and a half.

“Now it only takes us 40 or 45 minutes,” says Santana.

Sloan also must combat child obesity, another major issue facing Harlem youth. More than 46 percent of children between kindergarten and eighth-grade in East Harlem are obese or overweight, compared to 40 percent citywide, according to Department of Education statistics. The school serves a predominantly Hispanic student body; 96 percent have low enough household income to qualify for free lunches.

Sloan teaches his students to eat more healthily. Pizza, McDonald’s and Burger King have turned into “chicken, rice and healthy stuff,” as fifth-grader Darlene Salas puts it.

“Before I was here I used to eat a lot of junk food,” says Mohamed Yusef, a fifth-grader. “But now that I’m here I eat more healthy food and less junk food and I jog around the Jefferson Park track” across the street from the school.

Fifth-grader Melissa Lopez puts it more bluntly. “I know no one wants to be fat,” she says. “When you’re fat you can’t run anymore.”

In order to reach the students, Sloan takes a hard-line approach–one that, in the past, discomfited school administrators and teachers because he aggressively held parents accountable for students’ performance, he says.

Because of budget cuts, New York City’s public schools are producing fewer high-caliber athletes, Sloan says, and his old-school approach is meant to overcome those reductions. In class, his demeanor vacillates from playful to stern–if he feels the students are cutting corners.

“You’re out of breath because you didn’t do nothing this weekend,” Sloan shouts during a recent Monday morning gym class, as students slow their pace, doubling over, hands creeping toward their knees. “Unbelievable! It’s called that l-a-z-y word again. L-a-z-y: spells lazy.” The pace quickly picks up.

Since P.S. 102 principal Sandra Gittens approached Sloan seven years ago with the opportunity to join Mighty Milers, he’s had, as he puts it, “a happy marriage” with the school.

Last school year, over 10,000 students at 57 schools north of 96th Street in Manhattan participated in Mighty Milers or Young Runners, another New York Road Runners program.

“It’s great to teach kids a sport for life, very inexpensive, very accessible,” says Sperber, of New York Road Runners. “Running is that sport.”