But that was before she tried MP3 workouts. Taking advantage of sale prices last January at www.cardiocoach.com, she downloaded the first three volumes of a five-part series. Cardio Coach audios are designed to be used during any kind of cardiovascular exercise: running, stair climbing, even walking. For 30 to 60 minutes Sean O’Malley, the personal trainer who created the programs, offers encouragement as he guides the listener through a series of sprints – and for those exercising on machines, hills – that alternate with easier periods. Original music accompanies the ebb and flow of the intervals.