The secret to fitness craze Zumba's success?

Latin fitness craze Zumba is hot, hot, hot, with an estimated four million Zumba devotees around the globe. This week health website WebMD explores the secret ingredient to the brand's global appeal.

Alberto "Beto" Perez launched the technique in his native Colombia in 1986, and its success grew after he moved to Bogota and later to Miami. In 2002, he and entrepreneur Alberto Aghion began selling DVDs via infomercials.

Now Zumba is one of the hottest trends on the fitness market, with some 25,000 instructors in 40 countries, as well as its own clothing line, lifestyle magazine, and spinoff classes tailored for seniors, kids, and a sculpting class using weighted sticks that sound like maracas.

Part of its winning formula, says co-founder and CEO Alberto Perlman, is that Zumba (which is Spanish slang for "buzz like a bee") is safe for just about anyone since the steps can be modified to create a low-impact workout. He adds that teachers are encouraged to keep choreography simple, forgo over-directing so students can drop their inhibitions and "feel" the music, which fans say is a critical part of the fun of the style.

What's next for Zumba? This summer, the organization held its biggest members-only convention in Orlando, Florida, with 6,000 Zumba pros honing in on a new focus: fusion. Expect to see flamenco, hip hop, yoga, belly dancing, house music, African, Bollywood, capoeira, and Mexican dance moves coming to a Zumba class near you.

Other new dance-fitness styles emerging to compete with Zumba include Batuka, a hot trend in Spain in recent years that offers a Latin-infused cardio workout with a zen-like approach. Also, Latinva offers a heart-pumping workout with bachata, cha cha, cumbia, mambo, merengue, salsa, and tango dance steps.

Watch a Zumba fitness video featuring rapper Pitbull: