John Hawkes is shown lying down on the job but certainly not in comfort as Mark O'Brien in "The Sessions."
"Mark's spine was horribly curved and it's mentioned a couple of times in the script, that fact. So it's something as an actor that you have to honor," he said of Mr. O'Brien, who last moved his arms and legs at age 6 before contracting polio.
The actor, 53, helped devise and design a piece of foam the size of a soccer ball that was then taped midway up the left side of his back, tucked out of sight of the camera.
"Mark's limbs were twisted in a very unusual way, which I also wanted to honor, so I was lying in discomfort throughout. A minor amount of discomfort compared to the pain many people deal with daily in their lives.
"But it was a challenging thing to do, to find that body position and lie in it for long periods of time without having any movement at all below my neck -- I couldn't shift my body to relieve a certain burning or pain," he said.
The longest he stayed immobile was 40 minutes, and he and filmmaker Ben Lewin (himself a polio survivor) discovered it was sometimes more efficient for the leading man to stay clamped in the iron lung on set, too.
"It was often easier, on our low-budget, fast-moving film, to just continue to stay in the lung, lying on the ball while they were changing lighting or moving the camera into position," he recalled. "The Sessions" shot for 22 days in Los Angeles, which cheated for the main location of Berkeley, Calif.
The iron lung was inoperable and while Mr. Hawkes luckily isn't particularly claustrophobic, it was hot and uncomfortable. Early on, he discovered some pressure points and pieces of metal cutting into his neck and shoulder that were remedied.
Beyond the foam, there was no trickery. No body double, no prosthetics, no computer effects.
Mr. Hawkes, who leans toward indies such as "Winter's Bone," which earned him an Oscar nomination as an Ozarks meth addict, said some of the women in Mr. O'Brien's life were happy to talk about him.
"There was so much material, it was fantastic. I researched exhaustively for two months and was still learning more as we were shooting. Mark left us an autobiography that was very insightful and detailed about his early life," along with news articles, essays and poems.
He estimates he watched Jessica Yu's Oscar-winning documentary short, "Breathing Lessons: The Life and Work of Mark O'Brien," probably 40 or 50 times to gain further insight into the character.
"I love being specific as an actor; I think the more specific you can be, in truthful details, the more universal the story will become. And I wanted his survivors to see something of Mark in my portrayal."
Many of Mr. Hawkes' scenes are shared by Helen Hunt, who portrays sex surrogate Cheryl Cohen-Greene. She was the woman Mark turned to when he wanted to lose his virginity at age 38.
"The stroke of genius and great gift that Ben Lewin gave us was to make it possible to actually shoot the surrogate session scenes, our intimate scenes together, in chronological order." After all, he and Ms. Hunt were strangers before this project and only briefly met during script sessions with the filmmaker that were consumed by practical matters.
"Helen and I, without saying anything I think, took pains to keep a distance and not know each other. So there was no comfort when we began that first session scene; there's a lot of long takes in that scene and there's a lot of moments between us that are happening for the first time, in real time."
Film does that effectively, he suggested, while theater turns on rehearsing to find moments and then re-create them for an audience each night.
"Love scenes are always unwieldy, uncomfortable, awkward to shoot and they're normally edited to look like the perfect fantasy on some level. And we weren't interested in that. We found our way as we went, literally, and then as Helen and I got to know each other better, our characters did, as well, in the later scenes."
In one of the more memorable scenes in the movie, Mark is alone in his iron lung when an emergency strikes. Due to the expense of round-the-clock care, he didn't have aides who stayed through the night.
Mr. O'Brien lived quite poorly and his movie apartment is in a little better shape than his real home. "He didn't mind. He just loved being independent, that was really an important thing to him, to have choice.
"When he lived in an institution, as well meaning as people might have been, he felt often mishandled and cared for in a way that wasn't very tender or loving. Mainly, he just wanted to be asked what he wanted, occasionally, and that just didn't happen. So when he went to Berkeley, he felt like he had been freed.
"He really loved his time at the university and then after, he decided to stay there and continue to work. It was important to Mark to get out the word to people that it was actually cheaper for us as taxpayers for him to live independently than for him to live in an institution, oddly enough."
Mr. O'Brien moved to the University of California to study -- his 600-pound iron lung was hoisted by a crane through the space where his dorm window would have been -- at the school with the motto, "Let There Be Light."