Fizzy yoga has nothing to do with drinking champagne while practicing down-dog, then hanging upside down (though for some reason that's the first thing that came to mind when I heard about it). It's actually short for physiyoga; the 'fizzy' is just a cute abbreviation. 

This new type of yoga is a hybrid, including massage, physical therapy, body alignment, yoga poses, and other techniques, and it's taught by instructors who are both yoga teachers and physical therapists in a one-on-one setting.