stepper

Heliconia

I know this is probably a dumb question, so I will apologize. I bought a stepper. When I use it, although I do not step very fast, I do get out of breath. My legs also ache with the effort. I want to know if this is an aerobic exercise or a strength training (quads) exercise? What I really want to know is if this can be done daily like an aerobic exercise or if I should do it every second day? Thanks.