This is often a point of confusion. The belly needs to expand when taking a deep breath, and it cannot do so if one is “holding it in”.

Once the inhalation is complete, the inner muscles (not the outer 6-pack muscles) are the prime source of breath support and power.

The great tenor, Enrico Caruso, is reported to describe the breath support mechanism the same as when one “sits on the toilet, trying to go”.