Hello-- One of my fav books Reversing Asthma by Richard N. Firshein,D.O. says on page 21 if you are not breathing properly,using your diaphragmatic muscles to inhale then you are more than likely using your accessory muscles to breathe with.  You know that you are doing this when you are lifting your shoulders as you inhale.  This gives you a hunched look, which is especially obvious in people who have suffered from asthma for many years.

           My daughter is 21 and a vocalist so even though she has asthma the vocal training more importantly taught her to breathe.  Interestingly enough one of the first few times she had a voice lesson she had never used her diaphragmatic muscles to breathe with and doing this for the first time actually caused her to have to run to the bathroom and throw up. SINGING is not as easy as it seems. She is so glad that she has had this to teach her to breathe. 

           Also, if you cough alot you can cause a rib to be out of its place.  She has done this many times and our Specific Chiropractor adjusts it back into place.  My daughter does not have coughing with her asthma unless right before an attack along with nausea.  I wish I knew if the nausea is from "nerves" or from something else.  A specific Chiropractor is better than a Chiropractor and I do not know how to explain why.  If you can not find one close to you they are worth the travel.  My own Chiropractor drives 4 or so hrs to Atlanta to get his back adjusted.  I can not say enough about his care for my daughter as well as our whole family. We live in Charleston SC.  Hope this info is helpful.