By DICK ROTHSCHILD

You can hardly wander the calles and avenidas of Oaxaca’s historic district of an evening without encountering a groupo engaging in traditional music and dance. Yes, the old sones and chilenas are alive and well here. If you have spent any time in this city, however, you will also have discovered something else about it – to expect the unexpected. You need only to stroll to Conzatti Park any Tuesday or Thursday at 6 PM. to confirm that discovery.

As dusk falls in Conzatti, a former private garden and normally quiet oasis, you will suddenly hear a throbbing salsa beat. It seems to be coming from a semicircular platform in front of a small monument on the north side of the park.

Drawing closer the music, the throbbing Latin beat becomes louder and the incongruous sight of a dozen or so high stepping, gyrating women in t-shirts and warm-up pants comes into view. The women are in two rows spread out around a semicircular stone platform and are imitating with various degrees of success, the fast furious and fl uid movements of the instructor on the platform. They are doing Zumba. Zumba is a style of intense dance aerobics performed to a pulsating Latin beat. It incorporates body movements from salsa, fl amenco, merengue and other similar dances. The participants pump their legs, windmill their arms, gyrate their hips, clap their hands, dip, slide and spin to a pulsating beat, mimicking the movements of the instructor.

At the center of it all, on the slightly raised platform is the instructor. Maria Antonieta Diaz Garrido is a slim, curvy young woman with straight shoulder length brown hair. She wears a black knit top and pink warm-up pants and has her matching pink top tied around her waist. Her silver-tipped sneakers fl ash in the dim light as she undulates through the movements while barking out changes to her breathless followers like a drill sergeant - arriba! delante! atrás! regresso! The pace is relentless. At the end of the fi rst set she stands with hands raised, applauds the class, and encourages her students to applaud each other.

I am expecting a break to follow, allowing the dancers to catch their breath, but the pause is only momentary and the Zumba starts up again. I look down the lines of the step dancers, trying to form a composite picture of these women who seem happily engaged in what seems to me to be masochism to music. But they defy typing. They are short and slender, tall and muscular, average height and pudgy. Most are in their twenties to fi fties But, over there, the gray haired woman in the blue warm ups with the white stripe, she must be pushing sixty-fi ve.

Yet she is having no trouble keeping pace with the younger women in the class. She doesn’t even seem to be breathing hard. Go fi gure. The Zumba continues with hardly a break for almost an hour and a half. The only real pauses occur when Maria’s fi ve year old daughter strides on stage in a short pink dress carrying a fashionable magenta sequined hand bag and later when her nine year old son, nearby, loses control of the soccer ball he is bouncing to the beat of the music.

After it is over I approach Maria and learn that she is a professional zumba and aerobics instructor. She explains that she holds these classes at 6 PM on Tuesdays and Thursdays here in Conzatti Park and on Mondays, Wednesdays and Fridays at Llano Park. How long has she been teaching step aerobics? Twenty years, she tells me. She looks to be about thirty. “Por vente annos?” I ask, incredulously. “Si, si, por vente annos,” she replies. There must be something about Zumba that stops the time clock. At least it seems to have for Maria Antonieta Diaz Garrido.