Children are often 'belly breathers' because _______.

• A. Their intercostal muscles are not developed.
• B. They are consciously controlling ventilations.
• C. Their diaphragm is not functional.
• D. They are routinely hypoxic.

Answer: (A)

In children, breathing is driven mainly by the diaphragm because their intercostal muscles are not fully developed. The diaphragm contracts to push the abdominal contents downward, which makes the abdomen expand with each breath. Since the rib cage muscles aren’t yet strong, there’s less chest expansion and more abdominal movement, so it looks like belly breathing. As kids grow and their intercostal muscles strengthen, chest movements become more noticeable and breathing shifts toward a combination of abdominal and chest patterns.

Consciously controlling ventilation isn’t typical in normal, resting breathing for children, and the diaphragm is active and functional—not nonfunctional. Hypoxia isn’t the reason kids exhibit belly breathing in general.