“We are athletes,” Ms. Bass said. “We’re also well over the age of retirement.”
Lisa McNulty, the theater’s producing artistic director, said the piece was not only about using the language of sports to describe the life of a dancer, but also about investigating “what it means to live a life of physical pursuit, and the beauty and the tragedy of that.”
And it’s still funny. Ms. Barnes is capable of that rare thing in modern dance: appealing to a broad audience.
Her recent hits include “Three Acts, Two Dancers, One Radio Host,” created with Ira Glass of “This American Life”; and “Happy Hour,” an immersive office party that features Ms. Barnes and Ms. Bass dressed as men. In “The Museum Workout,” a collaboration with the author and illustrator Maira Kalman, Ms. Barnes and Ms. Bass lead participants on a two-mile trek — part guided tour and part workout — through galleries at the Metropolitan Museum of Art.
There, the idea was to create a way for people to be physical in a museum, which had the potential to change their experience of looking at art. (It was a success: The show has also been extended into December.)
In “One Night Only,” there is as much rigor and repetition as there was in its early iteration, but, Ms. Barnes said, they found the humanity in it. “That’s so much why I think humor feels useful and not just fun,” she said. For her, laughter is a sign that audience members are paying attention. “They understood something,” she said, and they also feel like, yeah, I’ve had a similar experience.”
In the show, Mr. Saenz de Viteri plays the announcer, improvising large parts of his script. Ms. Barnes and Ms. Bass engage in competitive running, spinning and the snapping of fingers.
Ms. Bass, left, and Ms. Barnes. CreditVincent Tullo for The New York Times
If Mr. Saenz de Viteri sensed a no-nonsense approach in their performance early on, he chalked it up to how this show in particular speaks to the reality of their lives: Their bodies require hours of maintenance and training.
“The culture believes there is a limitation to how long you can do this kind of thing for your job and to be onstage performing dance,” he said. “How do we make that interesting? Both because of the movement and because of that idea, we just started talking about athletes and sports.”
The collaborators began to consider how different the world of sports is from that of dance, though in both practitioners tend not to talk or to play a character but to move. That realization resulted in the question for the piece: How can you create an emotional arc around movement?
“Can you open up an audience to feel like they want to jump out of their seats at one moment?” Mr. Saenz de Viteri asked. “Or even boo, and feel like something is totally failing onstage? And can this movement that is so athletic lead us into a direction that creates a totally different relationship with an audience?”
There’s a personal experience buried in the work too. Ms. Barnes’s father was a marathon runner. “He’s in his late 70s now and has always had heart disease,” she said. “He isn’t running anymore.”
But she said that he was an inspiring athlete: “I couldn’t keep up with him. Even in high school, he was always outrunning me and I just felt like, God, if I could get as strong as my dad, I would be really strong.”
His speed began to dissipate until finally she was the one running faster. “Just seeing him and experiencing his frustration with not having the ability to be physical — I can only imagine his feeling,” Ms. Barnes said. “And I think being 44 and feeling so strong right now and having such a physical memory of how strong he was at 44 — there’s something about an understanding of how this is temporary.”
As she sees it, the severity of her early movement experiments for the show was something of a test. “Can we run in place for this entire song as fast as we can?” she asked. “We can. Great. Can we throw our right shoulder 800 times to this really fast song? We can. Great. It felt like I was setting up physical tasks.”
While those moments are no longer in the show — as Ms. Barnes put it, “who wants to watch that?” — they played an important part in creating it.
While “One Night Only” does have an end date (Oct. 8), the plan is to perform it as if each night were its last. And there will not be a point at which the show is frozen — meaning in a final version and ready for critics.
“I keep putting my fingers in my ear and going la la la la la,” Ms. McNulty said. “I’m a realist and I know that this company works outside of the traditional frame of a theatrical collaboration. I’m just going to pretend that it’s not happening. I’m going to treat it like a living, breathing entity.”
In a way, Ms. Barnes is being subversive. But it’s really just the way she operates: You show up and figure it out onstage in front of people.
“Even though we obsessively rehearse every detail, we’re trying to put ourselves in a situation where we’re nervous enough about what we’re doing so that we are so awake to what’s happening,” she said. “The way we’re really trying to undermine the Off Broadway run is to keep each show truly feeling like it is only happening this night.”