The dancers in Martine Pisani's deceptively simple piece consider rehearsals as play, but it's no free-for-all, writes Michael Seaver

It's 5.20pm and tired-looking dancers have finished showing me a section of Martine Pisani's upcoming work, Slow Down. When she suggests performing another extract, the dancers enthusiastically go to their starting places, ready to begin. Even after a hard day's rehearsal they are eager to dance some more. That's because this dance isn't work, but play.

"In life we don't play a lot," says Pisani, a French choreographer who lives and works in Paris. "That's why I choreograph." This choreography doesn't permit a playground free-for-all, but rather sets a series of instructions that the performers must follow as they compose and decompose movement. So one might have to show joy in his face alone, while another shows joy just in her body, while another remains completely neutral. Then they must swap tasks and take on another person's state. It sounds easy, but demands constant attention.

"You have to be part of a collective body," says dancer Robert Connor, also co-artistic director of Dance Theatre of Ireland. "You need to have your peripheral vision open at all times to see if another person's state has changed and therefore available to you. You also have to follow a pattern in the space and get your timing right so that it fits in with a singer. And all the movements are improvised so you are composing movement at the same!" It might seem like Sudoku, but for Pisani it is more like sandcastles.

"When children play they are very serious," says Pisani, adding that a child's playing can be an act of creation, amusement and learning all at once. And it's this sense of occupation that she wants to capture onstage. What she certainly doesn't want is the dancers to "show" that they are playing. "That's very different. Look at Buster Keaton, a hero for me. He never "shows" he is funny, and yet he is deeply funny. And deeply tragic too," she says.

It's a subtle distinction that is at the heart of her choreography.

Sans, a trio she choreographed in 2000, captures a sense of play that feels improvisational and yet is clearly structured. Although the three dancers seem to constantly meander through a playful stream of consciousness, the last two minutes of the work feature a fast-forward rerun of the previous 50 minutes of dancing. Sans was performed at Dublin Fringe Festival two years ago by members of her company, including Theo Kooijam, who is helping Pisani remount Slow Downfor Dance Theatre of Ireland.

"It's a question of intensity," he says. "How can you be playful without acting playful?" Pisani achieves this perfect pitch by combining freedom with rules. Individual movement might be improvised, but the precise instructions on space, timing and the general movement quality - such as whether it should be soft or angular - are sacrosanct. This gives rise to a sense of "play" that is particularly calm yet engaged, and discernable in other areas of life. She gives the example of someone cutting carrots in the kitchen: this natural movement, born of concentration, is what she seeks.

"One of the things to play with Slow Downis in only doing what you are doing, in other words not doing anything more than you are doing," says Connor. "Like what Martine says about cutting your carrots in the kitchen, it's that kind of simplicity of intent that can make a performer quite captivating." Connor admits it can be difficult to break performance habits and sometimes he needs to resist putting more strength or energy or intent into the dancing.

However hard she works with the dancers at finding this state, Pisani concedes that sometimes sitting in the audience she would like to have a knob to control the performance intensity. Yet she doesn't mind handing power over to the dancers and any lack of control is outweighed by the performance energy created onstage. "That freedom means there is the possibility of failure. But although I don't want failure, it is important that the possibility is there." For Pisani the theatre is one of the few places that provides a place to play, but also a place to re-taste what we have lost in modern life.

"This is why I called the work Slow Down," she says. "Where can we find a calm setting to take a good look at ourselves? Certainly not on television, because it's so in-your-face these days, and sometimes it's not to be found in the theatre either." Her uncluttered stage - there is just one moveable screen for dancers to disappear behind - is a quiet, almost meditative space for the action.

"Many choreographers strip down theatrical conventions, but with Martine it is for a bigger purpose, not just for the sake of it," says Connor. Although this unplugged setting might look unusual to Dance Theatre of Ireland regulars, Pisani's world-view fits their artistic doctrine. "The common element is our interest in the chemistry amongst the people onstage and what that shows us about the human being," says Connor. "But it's a very contrasting style, and that's really interesting, when someone's approach is very different to your own and yet speaks the same message."

Co-artistic director Loretta Yurick recalls when she first saw Slow Down. "It was like a window where I watched a little slice of life about people. I could see how they faced themselves, other situations, and how they occupied themselves. In its quiet simplicity it makes a statement that is as complete as more grandiose pieces of art. And I laughed a lot. About myself, about dancing and lots of other things."

• Slow Downruns at the Pavilion Theatre, Dún Laoghaire, from tomorrow until Sat, and then tours nationwide