When I was a young singer, my teacher, whom I adored, was a stickler for correct breathing. He called it “breathing from the back” and I could never get the hang of it.
Eventually, he said to me “You’re smart, you know what to do… go do it!” That was the end of my formal training. I spent the next few years struggling with my breathing, while working professionally. Somehow, I managed to get through performances.
I remember a particularily horrible radio broadcast of Vivaldi’s Gloria with a noted Canadian chamber choir. My breathing felt like lead. I gasped with every breath. I struggled to force it into the back: All to no avail.
Much later, I realized that to get the breath subtle, balanced, and in the right place, neither too high nor too low, you had to work imaginatively. It was also very helpful to realize that a balanced breath has an abdonimal component, and that this involves using the transverse and oblique abdominal muscles.
The breath will feel different to the singer, depending on body posture. If you breathe sitting in a chair, hunched over with your elbows on your knees, you will feel the abdominal component clearly. If you breathe in a standing posture, with a healthy feeling of classical presentation (not slouched), you may imagine the breath starting in the back, around the level of the floating ribs, and moving to the front along the edge of the rib cage.
The key to getting the correct physical response in breathing is to work imaginatively. You can give the appearance of correct breathing by forcing muscles to behave, but this kind of breathing is never comfortable.
Once the inhalation is balanced, you still have to master the release of the breath at the end of the phrase, or you will feel stuck as the music continues. This is especially true in bel canto repertoire, where the composers seem not to give you time to recover between phrases.
The same muscles that we use to take the air are the ones we use to support the voice; this is the “lotta vocale” or “vocal contest” between the inspiratory and expiratory muscles that is basic to the support/appoggio mechanism. You have to release the inspiratory muscles sat the end of the phrase so they can do their job in the inhalation.
Instead of taking air at the end of the phrase, release the residual air. This should allow the diaphragm to rebound and initiate an inhalation quite naturally. Practice this by deliberately taking more time to release the breath after every phrase, even it means adding beats to the music. Once you get the hang of it, you can eliminate the rhythmic distortions.