Final answer:
Diaphragmatic breathing involves the expansion of the belly with inhalation and its contraction with exhalation.
Step-by-step explanation:
The diaphragmatic breathing also known as deep breathing, involves the contraction of the diaphragm muscle.
When the diaphragm contracts, it moves downward, causing the thoracic cavity to expand and allowing more air to enter the lungs.
When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. As the diaphragm relaxes, it moves upward, decreasing the volume of the thorax and causing the air to be expelled from the lungs.
A shallow breath, called costal breathing, involves the contraction of the intercostal muscles between the ribs. In this type of breathing, the belly does not expand significantly with inhalation and contraction with the exhalation is minimal.