There is a lot of specialization in exercise classes. Sometimes the specialization is in what effect one wants: cardio for strengthening the heart, weight training for strengthening the musculoskeletal system, core for, well, the core, and so on. Sometimes it is in style: zumba and spin both are cardiovascular (though of course with strengthening and sculpting effects), but quite different in style. Sometimes it is in target population: zumba gold targets an older exerciser, as does fit for life, though the music and movements will be different.
All people get older. That is a baseline of the human condition. But although the effects of age, broadly speaking, are part of the life cycle, how quickly and how much they develop is variable. We cannot change our DNA (yet). Some people have greater risks for heart disease, or cancer, for instance. But lifestyle choices can have an enormous impact across our lives on how we age, and even the way genes are expressed can be affected by those lifestyle choices.