For the first four weeks, Pearson, 35, literally crawled up the stairs to her apartment because walking caused her to break out into a sweat from the muscle fatigue. Every night she soaked her sore muscles in a medicinal bath before falling into bed by 10, which not surprisingly put a crimp in her dating life. In the morning she slathered herself with a smelly muscle balm and didn't care when commuters on the subway moved away from her.
But Pearson, who undertook her five-week experiment almost as a journalistic dare after Anderson claimed that her method would work for any woman of any size, discovered "it is doable," she said.
She argued that Anderson's regimen is much harder than any other, but it's also more effective. Pearson went down two dress sizes and lost 16 inches around her body in five weeks.
It's a wonder Pearson didn't get injured, Dr. Andrew Feldman told ABCNews.com.
"It doesn't take a rocket scientist to understand there's sore and then there's sore," said Feldman, the chief of sports medicine at St. Vincent's Hospital in New York. "Somebody who feels like they were run over by a train -- they are overtraining. That's not only bad for injury. It's bad for the muscles. They need recovery time. The off days are as important as the on days."
In his 15 years of practicing, Feldman has seen many people injured after trying to mimic something they see on television, video or the Internet.
"Either their bodies are not flexible or ready for it," he said. Or he'll get the "weekend warrior" types who go from working out two days a week to five and end up tearing a tendon or breaking a bone.
He said people often make the mistake of looking at celebrities and thinking, "That's something anybody could be doing, because they're just like you and me."
In reality, "someone like Madonna is not unlike a pro athlete," said Feldman, who is also the head team physician for the New York Rangers.
Celebrity trainer Kathy Kaehler agrees. "Madonna has been putting in years and years of this kind of training," she told ABCNews.com. "A friend of mine trained her in Los Angeles and those were two- and three-hour workouts. She used to run miles and miles. Someone who pops into that type of regimen is putting themselves at increased risk for injury. Their system not prepared for that."
That hasn't stopped people in the last 20 years from asking Kaehler to help them look like Jennifer Aniston, whom she has trained. When Aniston was on "Friends," she got so many requests from people who wanted arms like hers that Kaehler's mantra became "would you like me to cut her arms off and replace them with yours?" she said. "It got to be almost so silly."
Rachel Nichols, one of the stars of the ABC series "Alias," said celebrities have both an easier and a harder time staying in shape.
"A lot of times people look at someone with this amazing body and say 'I want that' and I understand. It does look easy from someone's perspective that an actor has a trainer and lots of free times that a regular person doesn't have," she said. "But the regular person doesn't have [the] scrutiny of everyone in the world judging them if go up a few pounds or have cellulite. So it's both easy and a lot of work."
Before getting the job on "Alias," Nichols, a former model, said her idea of staying in shape was "living on cigarettes and Diet Coke." Though the actress was thin, her body was soft when she began working out with Waters.