I guess I can only speak for myself, but I have NEVER heard any discussion that large-busted women have to compensate for balance when they run.  I know I don't have balance issues when I run.  The only issues that I have ever heard of relate to women not wearing a supportive enough bra.  If everything is not held "in place", then you will get upper back pain & breast pain.  I think that if you get the support issue corrected, then any stresses on the back & neck will go away.  That's been my experience anyway.  You make it sound like we're in a struggle not to topple over when we're running because we're so top-heavy.

Carey, You need to look for a compression bra, usually available at most running stores, but for best prices, buy online.  Be prepared to shell out $40-$60, but it is definately worth it.  Moving Comfort, Fiona Full-Figure (www.movingcomfort.com) and Enell Sports Bras (www.enell.com) are pricey, but they are both excellent quality and last a long time if you follow the care instructions and don't toss them in the laundry.  Never buy a "running bra" that is sized, i.e. S, M, L, XL, these just don't cover those of us that are DD or larger and you will not find something that works at Target, Walmart, etc.  You have to buy quality to get the control you need, so be sure to actually measure yourself as indicated on the websites to get a good fit.  If you are having problems with chafing a little butt balm, yes it's exactly what you're using on your baby's behind, will provide relief.  With a compression bra you won't have the continued bouncing, but they do take some getting used to.  If you're going to continue to run, you have to have good equipment.  FM

Carey,

I have lost 41lb this year and reached my goal weight (yeah me).  I am unsure how mcuh wieght you have to lose but I thought I would let you know that it was only in the last 5% of my weight loss that I lost anything from my bust.  Initially it all came off my back.  So if you are still losing maybe you will come down in size. I was a DD and me now a d-e depending on the make. 

I throughly recommend going to a bra shop to be fitted properly.  Even though department stores have people to do this they are not all specialists.  Heck the last lady to fit me at Myers was in the music and movies dept on the weekend. Anyway, congrats on the weight loss and all the best with finding a solution,

Michelle

My experience with Champion brand has been they work great for about 2 weeks, then they stretch out and you have to toss them and buy new.  That gets expensive if you're running every day.