Music Counting As Exercise?

LittleCanary

I was browsing through the exercise database earlier, and much to my surprise, playing the piano was listed under cardio. I'm a keen pianist and I do a fair bit of practise every day, but I'm just wondering how many of you would actually consider it to be exercise? I'm also wondering if singing (i.e giving the diaphragm a good workout, not just warbling into a hairbrush!) would count, and if so, why it isn't listed in the database?

Does anyone have any thoughts?