Most runners in the Baton Rouge Beach Marathon on Dec. 1 probably didn’t notice an internationally known opera soprano in their midst. She dresses a bit differently for running than for “Rigoletto.”

But friends and music lovers who remember her growing up in Baton Rouge also may not have recognized Lisette Oropesa, either. Many would never have expected to see her in a marathon, which made her 26.2-mile run as much a celebration as it was a challenge.

Oropesa, 29, crossed the finish line with her husband, Steven Harris, in 4 hours, 51 minutes, 52.3 seconds, which placed her 68th among women runners. The time didn’t matter. Oropesa completed the first marathon she’s ever run.

“It’s been the best thing that’s ever happened to me. I love distance running,” said Oropesa, who now lives in New York, close to the Metropolitan Opera where she frequently performs. “I love the relaxation that comes from it. I love the mental power that you have to harness and learn to use. I love everything about it.”

Oropesa knows that, to many, her avocation defies the stereotype best expressed by the often-used sports saying, “The opera ain’t over till the fat lady sings.” Like all stereotypes, the image of overweight operatic sopranos is a mixture of fact and fiction. Oropesa has lived both ends of that equation.

“When I left Louisiana and moved to New York, I weighed 210 pounds,” she said. “When I got to the Met as a young artist, they told me I needed to lose weight because it would really affect my career if … my voice was suitable for young, romantic roles but I didn’t look the part.”

That was seven years ago, and Oropesa took the advice seriously. She began going to the gym and eating a vegan diet and lost 50 pounds, and roles came her way. Two years ago, she and Harris — then her boyfriend, whom she married on Oct. 15 — took up running. It was a lot of huffing and puffing at first, but they stayed with it, and about a year ago ran their first half-marathon.

All who finished the race received a medal. It wasn’t quite as big a deal as Oropesa’s first opportunity to sing at the Met, but it was meaningful.

“I never had a medal in sports in my life, by the way,” she said. “I was the last kid to finish the mile in P.E. in school. I was never picked on any teams, always the last one. I was that kid. I got my first medal and just fell in love with distance.”

That love has rewarded her handsomely. Oropesa continued to lose weight and is now 125 pounds, removing any obstacles to roles her former size would have denied her, and enhancing her ability to handle the physical requirements of singing demanding songs while acting in heavy costumes under bright stage lights.

“Except for certain muscle coordinations, the most important thing you can do is equip yourself for the breathing that you use in singing,” said Robert Grayson, Oropesa’s mentor and Kirkpatrick Professor of Voice at the LSU School of Music. “We are up there singing on stage across a 70-piece orchestra with no amplification, no microphone, so it becomes a real athletic event. The fact that she’s doing this only strengthens her ability to sing well.”

“There’s also a sense of confidence that comes with it,” Oropesa said. “With singing, a lot of times you open your mouth and you’re not sure that the note is going to be there, or you have a negative thought and it will come out and it will affect the phrase. You’ll be nervous and things like that. It’s the same thing with running.

“With the marathon, the distance training has taught me that your attitude toward every step is what’s going to make that step successful or not successful and what’s going to make that mile successful or not successful. As we were running the race and getting to the hard, hard parts, it’s all in your head, completely. Your body has the fuel. If you’re not injured and you’re not about to die of thirst or heat exhaustion, you can do it. It’s all there. You just have to believe that you can do it.

“It’s the same thing with singing. I can sing a high C. If I don’t believe I can sing a high C, I won’t sing a very good high C. It’s very similar, very parallel.”

Grayson, whose career as a performer spanned the early 1970s to the early ’90s, said it wasn’t until the mid-’80s that opera singers began taking fitness more seriously. It is far more common now, but there is a big difference between running to stay fit and running a marathon. Oropesa said she knows only one other opera singer who has done that.

Oropesa ran four half-marathons before making the jump. She originally planned to run in the Detroit Marathon just before she was to perform there in October, but a scheduling mix-up prevented it. Then, she discovered the Baton Rouge Beach Marathon, which she could fit into her trip home for Thanksgiving.

Since it was a warm day, Oropesa and her husband took the advice of renowned running coach Jeff Galloway and set a conservative pace. They now have higher aspirations.

“I can’t wait to do another one,” Oropesa said. “My goal, I would love to do a four and a half hour, and then I’d love to do a four hour. I have goals that I want to hit in my life at some point.”

That applies to her career, as well. Grayson said that Oropesa’s career peak should be in her mid to late 30s.

“She is already coming on as an international soprano,” Grayson said. “Over the next 10 years I think we will see that international sphere growing, adding places like La Scala and Covent Garden (London’s Royal Opera House). She’s already hitting the major theaters in this country.”