Brooklyn —

Louis Maffei calls it a marathon within a marathon.

During every New York City Marathon since 1979, the band from Brooklyn’s Bishop Loughlin Memorial High School has played the “Rocky” theme song for three hours straight as runners pass by.

Maffei, the band’s musical director, has conducted the band for all 36 performances, watching as the group grew from 12 students to more than 200. This year, Maffei’s band stretched near an entire city block.

The band got started with the song just a few years after the movie was released. The catchy theme song of the 1976 boxing film, with its iconic and punchy horn intro, caught on with the fledgling band. “See, this was back before everyone was sick of the Rocky movies,” Maffei said. “And we got response from all over—we became the talk of the marathon, we became the original marathon band.”

Over the following decades, the marathon’s growth demanded more from the students. In the late 1970s, only a few thousand runners would come out on race day, compared with more than 50,000 this year. The increase meant that runners streamed by the Loughlin band for a longer time.

“The same runner is only here for less than a minute, and they all want to hear Rocky,” Maffei said. “A couple years I tried to change it, but even ‘Eye of the Tiger’ they didn’t freaking want. They want that ba-da-baa.”

Weather has always been the wild card threatening to thwart the performance, but the Loughlin band hasn’t missed a marathon since the tradition began. On Sunday, clouds hung over Brooklyn as runners packed Lafayette Avenue, but no rain fell and temperatures hovered around 50 degrees. While some onlookers danced at the barricades, racers slowed their gait and clapped along, smiling at the performing students bundled up on the risers.

“I love this song,” said Alison Marks, 28, who was watching the race from across the street. “If I were running, it would be exactly what I’d need.”

Chris Jacobson, 45, camped out down the street with signs supporting his wife, who was running her first marathon. “I remember when this song came out, when Rocky came out—it was huge,” he said. “It’s great they’re still playing it now.”

Maffei, who turns 62 in January, is unsure about how many more years he has at the helm of the Loughlin band.

“I keep on going back and forth. You get cranky when you get old, and I don’t want to be remembered that way.”

Regardless of when he puts down the conductor’s baton, Maffei will be remembered for building a music program from the ground up—a program that now performs 40 concerts every year. Leading the students in a yearly three-hour rendition of “Gonna Fly Now” is the signature of his tenure.

“It’s an inspiration,” Maffei said. “It brings the band together as a unit.”