TEHERAN (Iran) • To those Iranians shaking their hips to Latin American music during Zumba exercise classes, Iran's Muslim clerics - and an American company - have the same message: Stop it. It is illegal.
The country's Zumba fans, however, are refusing to back down.
Iran has undergone a health revolution in recent years, with gyms and fitness clubs opening in many neighbourhoods. Men lift weights to become buff, women sweat in aerobic classes to stay lean.
As in many countries, Zumba, an aerobics dance class, has attracted a wide following in Iran, especially among women who gather a couple of times a week to work out to upbeat tracks by singers such as Ricky Martin and Shakira.
"It's fun. It's positive," said Ms Sunny Nafisi, 33, a Zumba instructor, who works in an upscale Teheran gym.
But recent days have not been fun at all, she admitted.
An edict issued this month by the head of the Sports for All Federation, a government institution promoting sports and a healthy lifestyle, effectively banned Zumba classes for being contrary to Islamic precepts.
Since then, Ms Nafisi's phone has been buzzing with messages from depressed Zumba aficionados who feared their classes were axed. Even her mother-in-law called from California to ask if this was the end of Zumba in Iran.
"Of course not," said Ms Nafisi. "Zumba will not be stopped."
Coming together for fitness dancing is just one of many examples of the tensions between Iran's changing middle-class society and those ruling the country.
Since the 1979 Islamic revolution, Iran's Shiite Muslim clerics have codified into law hundreds of lifestyle regulations - from drinking alcohol to dancing - meant to keep their flock on the right path. Some of these have been deemed illegal.
But enforcement can go only so far in a society completely changed over the last 40 years.
While prosecutions can result in fines or even caning, they are not common and, last week, thousands of men and women danced in the streets to celebrate the Iranian national football team's earning of a spot in the World Cup next year.
Today, many Iranians shrug off most of these sins, saying it should be up to individuals to decide if they commit any.
In practice, this means that popular but proscribed activities, including Zumba dancing, are often tolerated if they take place semi-hidden or under a different name.
"I taught Zumba for years here," Ms Nafisi said. "But instead of calling it Zumba, I called it 'exercise to music' so no one would notice."
Other names used included "body rhythm", "advanced aerobics" and "Mumba".
Then, in a sequence of events not uncommon in Iran, another Zumba instructor started calling her classes by their real name four years ago.
When authorities did not react, many other instructors, including Ms Nafisi, swiftly followed.
"Suddenly it became free," she said. "Maybe they just stopped caring."
Until this month. In a letter, the head of the Sports for All Federation, Mr Ali Majd Ara, decided that Zumba was not one of the accepted sports. The problem: Making "rhythmic movements" or "dancing" is illegal, his letter said.
"Suddenly, someone comes and says this or that is not allowed," said Ms Sepideh Heydari, 33, a nail specialist, who has been taking Zumba classes for the last two years.
"I become happy and my spirit is uplifted when I dance," she added. "That is probably exactly why they disapprove of it."
For Ms Nafisi, Iran's clerics were not the only ones opposing her.
So, too, was the legal department of Zumba Fitness, the United States company behind the fitness craze, which, she said, had revoked her instructor permit last year when she had written on a Facebook page related to the company that she worked in Iran.
Some US companies interpret sanctions on Iran rigidly and she received a letter saying that only if she moved to a different country would she get her instructor's permit back.
The company did reimburse some of the fees she had paid for training in Dubai.
Still, Ms Nafisi said she will go ahead with her Zumba classes in Teheran, no matter what clerics or lawyers say. "I have 40 students - they want to work out," she noted. "I'll just rename the class."