Durational performance tests an artist's endurance—think of Marina Abramović, who spent days seated with no access to food, water, or a restroom; or Vito Acconci, who masturbated eight hours a day for 14 days.

For transgender artist Cassils, recently named a Guggenheim Fellow, duration performance is a way of challenging assumptions about bodies in society. In their work, Cassils questions the audience’s role in art: In Inextinguishable Fire, for example, Cassils appears to light themselves on fire, while in Becoming an Image, Cassils challenges the audience's comfort level by beating a mass of clay in the near-dark.

Based in L.A., Cassils has capitalized on the city’s reputation for celebrity and mass-market culture to create works that question what it means to produce for an audience that does not really know you.

We caught up with Cassils to discuss the practice and purpose behind their hyper-physical work.

When did you first start working with durational performance?

The first work I started training for was in 2011 for Tiresias. I pressed myself up against an ice sculpture of a neoclassical male torso and melted it with my own body heat. I really tried to bulk up for that.

I also underwent a very rigorous durational performance in Cuts: A Traditional Sculpture. Rather than starve myself like Eleanor Antin did in Carving (1972), I ingested the caloric intake of an 180lb male athlete. I took six weeks of steroids and trained incredibly rigorously to see how far I could push my physical body to complicate what is “expected” of a “female” body.

How do you find a stopping point?

For Cuts, I gave myself a six-month [window] because that seemed like a manageable start and end point. I thought of it as an empowering project: Find this newfound strength and have this gender expression without taking hormones and surgery. But the rigor of the project became such a tight noose that it was a mantle of oppression in a way that I don’t think I had expected.

In your work Becoming an Image, you bring viewers into an unlit space and repeatedly beat a large chunk of clay into an abstract shape. Why perform this piece in the dark?

I decided to make a work about the problematics of archiving and how we historicize images. Visitors were led in by ushers in total darkness and placed in a circle. In the center of the room was 2000lbs of modeling clay. I entered unbeknownst to them and systematically beat the clay as hard as I could. Very little of what you experienced of the work was "seeing." When the camera flash went off and you saw it, because your pupils were dilated, you had an intense retinal burn of me frozen. The idea was to turn everybody’s body into the mechanism of being a live archivist.

The piece was commissioned for an exhibition at the ONE Archives in L.A. as part of a larger exhibition called "Transactivation," where they asked artists to speak to the missing Ts and Qs in the archives.

How was the piece documented?

The photographs are all taken blindly, just as I am blind and the audience is blind. It takes away the power of the white male photographer to frame and objectify me. I was interested in messing with that traditional mode of documenting, and reversing that power paradigm. Any image that was good was purely accidental.

How do you incorporate stunts in your practice?

I’m interested in how images of violence are created and how technology affects our understanding of images of violence. I made a piece called Inextinguishable Fire, where I performed a stunt of being lit on fire. It’s a single shot film that slowly pulls back on a dolly. You think you’re looking at a burning body, but eventually realize that you’re looking at an image constructed to manipulate you and unpack the mechanism of its production.

I’ve also been working on a series of performances called The Powers That Be, in which I choreograph fights without hitting anybody. It’s all about reacting as if you’re being hit. I realized that if you take the other members of the fight out, and you’re doing the choreography really well, it looks like you’re fighting a ghost or a force.

What are you currently working on?

I’ve made bronze castings of the clay bashes. The piece asks the formal question: What is the shape of violence? I’m taking these sculptures and placing them in public sites where acts of violence actually occurred. We’re putting this bronze sculpture onto this rolling splint and I’m going to push it to these sites. It’s a performance called Monument Push, which will bring the show, "Cassils: Phantom Revenant," at The Bemis Art Center in Omaha, Nebraska to a close.

The next major thing is my new solo exhibition at my gallery, Ronald Feldman Fine Arts, where I’ll be showing my bronze piece there because I’ve never shown it in New York. I’m also working on a sculpture made of urine. I’ve been saving all my pee since the repeal of the Obama-era order that allowed kids to piss in their bathroom of choice [Title IX]. I’m going to exhibit the amount of urine that one body would have to [expel] from the date of the residence of the order to the opening in mid-September.

Cassils' work is on view at the Beall Center for Art + Technology in Irvine, California, through May 13 as part of "MASCULINE ←→ FEMININE,", and at the Leslie Lohman Museum in New York through May 21, as part of "Expanded Visions."