Marcelo Martinez lowers himself to the floor, spreading his legs out wide. When his split reaches a "T," he takes an elastic band, hooks it to one foot, then, pulling the band around his back, hooks it to the other to stretch his legs even further.

Just minutes earlier, Martinez had effortlessly lifted ballerina Lilyan Vigo above his head, lowered her to a deadweight position, then spun around a half-dozen times, never letting her to the floor.

Ballet takes extraordinary strength, stamina and flexibility, and this past weekend’s performances of "Romeo and Juliet" featured dancers from the Carolina Ballet of Raleigh, N.C., who have taken those athletic skills to their highest level. And it’s all in the service of an art form that combines motion and emotion.

Martinez said he first learned to use the elastic band, called a Thera-Band, in Brazil when he saw his ballet classmate using a bicycle tire to stretch. "I thought that was pretty interesting because when you hit 180 degrees on the floor, there’s no more you can go to stretch more, so with the Thera-Band you can go a bit more," said Martinez, a native of Paraguay.

He uses the Thera-Band in split position but also standing, balancing on one leg while pulling his other leg behind his head into a "Y" position.

"You have to build strength and elasticity. You cannot have just elasticity, because then you’re not going to have control," Martinez said. "The strength comes with the Thera-Band, because the little pressure that I have from the elastic, it can build more strength."

Aside from this extreme use of the Thera-Band, ballet dancers pursue a variety of conventional exercise and fitness regimens to stay in shape. Pilates, yoga, stretching, all are part of a typical dancer’s routine, said Timour Bourtasenkov, a prize-winning dancer for the Carolina Ballet. Bourtasenkov wowed students at Ballet Hawaii classes last week by kneeling, then stretching his body back so that his shoulders were fully resting on the ground.

"Takes practice," he said simply, punching his stomach, which gave a solid "thump."

BALLET DANCERS typically work six days a week, six hours a day, rehearsing entire routines or individual techniques. That by itself imposes tough physical demands on their bodies, but they often supplement that with workouts at the gym, which can garner envious looks from other gym users.

"I think everybody’s thinking, ‘What is she doing here? She’s 100 pounds, get her away from here,’" said Vigo. "But it’s basically for stamina. … A 15-minute pas de deux, we can’t stop and take a break halfway through, so we need to be able to get through it all. So just walking on the treadmill for 20 minutes helps you get that heart rate going so that you can actually get through it."

Vigo said the 2010 film "Black Swan," featuring Natalie Portman’s Oscar-winning performance of an emotionally unstable ballerina, was "Hollywood" in its depiction of the physical and psychological stress that dancers experience. But some of it "hit pretty close to home," she said.

Mark Tucker of the Eugene (Ore.) Ballet Company said that as a ballet dancer, he is "almost addicted to that exercise and endorphin workout."

Tucker grew up in Hawaii and still swims and surfs to stay in shape, but his main exercise is from the technique classes and rehearsals that come with his profession. Like many dancers, he avoids heavy weightlifting that can add bulk, though he’ll find himself lifting a ballerina dozens of times a day, often supporting her with only one arm.

"A lot of it is coordination, the way you work with your partner," said Tucker, who said he does push-ups — one- and two-armed versions — mornings and evenings. "You feel when she moves and you use her own movement to help lift her up in the air."

Ballet dancers, aside from pursuing extreme flexibility and control, also need stamina. A diet heavy in protein is important for male dancers, who need sustained energy for the lifts. Before a performance, they’ll have a carbohydrate-heavy meal as a source of quick energy, Martinez said.

Ballet differs from most sports in one key aspect. Though there are ballet contests and it is considered a competitive profession, the emphasis is on artistry — that moves be done perfectly every time, in sync with music, to create the greatest emotional impact.

"You have to perform," said Martinez. "You have to give the artist inside of you, because if it’s only pirhouette, jump, and all this circle stuff, then it doesn’t become art any more."