By Amy Zimmer
DNAinfo News Editor
MADISON SQUARE PARK — A sweaty, pulsing Zumba "flash mob" took over a patch of Madison Squre Park Monday morning.
Most of the crowd dancing to the Latin beats, though, came from the ranks of the city's Health Department.
The outdoor Zumba class, after all, was a Bloomberg Administration publicity stunt for its "Make NYC Your Gym" week and its recently overhauled BeFitNYC online search engine to find free or low-cost fitness events.
The city tapped a company called Go Guerilla Media to spread the word through Twitter and other social media outlets to organize the flash mob — an impromptu gathering often reserved for protests rather than city-sanctioned promos.
If Sandy Bernard, a dog walker passing through the park during the Zumba class, had known about it, she would have rescheduled strolling with the pooches, she said.
"I should go to the gym," said the 68-year-old, demonstrating the jiggling of skin under her upper arm. "If they did this every week, I'd be here all the time. Dancing is the best workout because you're having fun."
"If I do that I'd drop dead," said Victor Earthman, "over 66," watching the crowd shimmy around and do knee kicks.
But he appreciated the reminder to exercise.
Since he's retiring in August after 37 years as an MTA bus driver, he said, "I'm definitely going to need to do some kind of workout to stay alive because when you retire, you can't just sit down."
He said he recently bought some books on Tai Chi.
Many passersby took cell phone pictures but declined to jump in.
"I go to the gym every day on my lunch break," said Pamela B., 46, an investment banker in a beige pants suit who declined to give a last name. "But at my gym, I can shower."
Health Commissioner Thomas Farley ticked off a list of ailments that exercise cuts the risk of: heart disease, stroke, high blood pressure, depression, colon and breast cancers and osteoporosis.
"Thirty minutes of walking a day five days a week lowers the risk of death by 20 percent," said Farley, who started a morning runners group for his colleagues on Monday, which he plans to continue all summer.
Other city officials said they're getting co-workers involved in physical activity. Deputy Mayor for Health and Human Services Linda Gibbs said she'll organize her yoga classes and volleyball group using the BeFitNYC site.
Farley urged New Yorkers — 30 percent of whom report engaging in zero physical activity — to get fit on their commutes, getting off a subway or bus stop early, or by doing "indoor hiking" and climbing up building stairs.
Other public fitness events this week in Manhattan include a BeFitNYC Challenge in Harlem at 163 West 125th Street from 3 to 5 p.m. with jump ropes and hula hoops and more Zumba and other classes on Sunday in Washington Square Park from 11 a.m.to 3 p.m.