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