Catherine,
I believe running a few miles(if you mean 2-3) a day or every other day is
moderate rather than heavy exercise. For persons training for marathons they
usually run 40 miles or more a week. I am not aware of any reports that
moderate exercise effects prolactin secretion or causes LAM. I just recently
worked with a 1st time mother who was having problems breastfeeding. I saw
her for the first time 1 week post delivery. She reported very little breast
changes during her pregnancy and following delivery. She is a dietician and
works as a fitness instructor in a wellness center. She is also a marathon
runner (just qualified for the Boston) - so she's also FAST. After much
effort (i.e. pumping post feeds, SNS, etc) there was very little response in
the way of milk volume. However, studies thus far have not shown exercise to
have a negative influence on lactation. have not. In obtaining a history
from this mother, however, she did say that she had anorexia  and LAM as a
teenager. It would seem to me that this could significantly effect the
development of glandular breast tissue. Interesting to consider. BTW, her
husband said he was going to be waiting for her at the finish line at the
recent Tenneco Marathon here in Houston because they want to have another
baby. She has already asked me if I think she will be successful this next
time. We'll see.