I attended and still do, a very popular franchised worldwide aerobics program before pregnancy, throughout (until the day of my labor), and returned 3 1/2 weeks later. I did not find my daughter to be fussier than usual, or refuse the breast, never had any problems with diminished milk supply after exercising. I always made sure to stay hydrated, drinking throughout the day (not just before and during class), and tried to rest and eat enough. I do not remember all the details of the original post about this topic, but am wondering if the mother was setting her sights too high - for me, since staying fit has always been fun and a priority for me, it was the *one* additional thing I did when I had to limit activities as the mother of a young baby - I'd much rather dance than clean! Also, I really tanked her up before leaving - nursed her well just before leaving, was back in an hour and a quarter or so, and put her back on the breast right away when I returned. Jane Khondker La Leche League Leader