Illusionist David Blaine, whose week-long stay in a water-filled sphere on the plaza at Lincoln Center captivated the city, last night failed to break the world’s record for holding one’s breath under water. Shackled with handcuffs at eight different points on his body, the daredevil performance artist managed to hold his breath for seven minutes and eight seconds before giving up and being helped to safety.

“I’m humbled so much by the support of all of you from New York City and from all over the world,” Mr. Blaine said upon emerging from the tank. “This was a very difficult week, but you all made it fly by with your strong support and energy. Thank you so much, everybody. Thank you all and I love you all.” Mr. Blaine was taken to St. Luke’s-Roosevelt Hospital for treatment last night.

Despite the failure, Mr. Blaine apparently did set a world’s record for being continuously submerged in water. Even his personal physician, Dr. Murat Gunel, had advised him to abandon the attempt.

The crowd that filled the plaza to overflowing greeted Mr. Blaine mostly with cheers as he was pulled from the tank, wrapped in a towel and given oxygen, but there were scattered boos as well. Mr. Blaine, 33, had been attempting to break the record of eight minutes, 58 seconds without a breath. Many observers counted down with their own watches, cheering as each minute passed. Most were audibly disappointed when he failed.

“This is not magic,” a spectator from East New York, Kamahl Palmer, 17, said. “If it were magic, he would have pulled it off easily.”

The stunt began May 1 when Mr. Blaine first submerged himself in what looked like a giant snow globe, which was filled with 2,000 gallons of saline-infused water kept at a constant temperature of 98.6 degrees. He spent hours each day waving to thousands of spectators and fans, including actor Colin Farrell.

The underwater exploit was the latest attention-grabbing feat of the performance artist, whose prior stunts have included freezing himself inside a block of ice, eating glass, and burying himself for seven days without food or water in a plexiglass coffin.

Because Mr. Blaine is both a magician and a performance artist, observers said it is hard to know where reality stops and illusion begins. Mr. Blaine began training for the stunt five months ago with some Navy SEALS, and lost 50 pounds so that his body would require less oxygen. His regimen also included cardiovascular and stretching exercises to reduce his resting heart rate by about half, making it easier for him to hold his breath longer, his trainer, Kirk Krack, said.

“Is it magic? I don’t know. I think it’s more of a performance happening,” Thomas Solomon, who himself escaped five from five sets of handcuffs after being thrown into the East River in 1995, said.

Mr. Blaine’s spectacle “is an endurance test, as far as I know,” the biographer of the famed magician Harry Houdini, Kenneth Silverman, said. In 1926, Houdini escaped from a sealed underwater coffin at the Shelton Club hotel on Lexington Avenue (now the New York Marriott East Side hotel).

The chief of pulmonary and critical care medicine at New York Hospital’s Weill Cornell Medical Center, Dr. Ronald Crystal, said Mr. Blaine might have suffered brain damage or a heart irregularity had he been deprived of oxygen too long. Dr. Crystal said holding one’s breath for nine minutes was difficult and uncomfortable, but possible with training. “It’s the extremes of what humans can do,” he said.

A dermatologist at the Tribeca Skin Center, Dr. Sherry Hsiung, said prolonged exposure to water could cause skin to slough or rub off – a problem Mr. Blaine was reported suffering from last week. “Underwater, the skin loses some of its protective properties,” she said.

Dr. Hsiung also said the sealed mask that Blaine wore for most of the week in order to breathe underwater would also rob his skin of oxygen, thus clogging pores and triggering breakouts. Any adverse effects of the week spent submerged should disappear within three weeks, according to Dr. Hsiung – about the time it takes the body to produce a fresh new layer of skin.

An East Side dermatologist, Dr. Francesca Fusco, said that although the immersion might cause swelling or exacerbate preexisting skin conditions, such as eczema, it might also have some benefits. “If he had rough heels and knees, they’ll be a lot smoother now,” Dr. Fusco, an assistant professor of dermatology at Mount Sinai Medical Center, said.