Final answer:
Forced breathing, also known as hyperpnea, occurs during exercise or actions that require active manipulation of breathing. Inspiration and expiration happen due to muscle contractions in various muscle groups, including the neck and abdomen.
Step-by-step explanation:
There are different modes of breathing, and one of them is forced breathing, also known as hyperpnea. Forced breathing can occur during exercise or actions that require active manipulation of breathing, such as singing. During forced breathing, both inspiration and expiration happen due to muscle contractions.
Accessory muscles of the neck, like the scalenes, contract during forced inspiration, lifting the thoracic wall and increasing lung volume. Accessory muscles of the abdomen, like the obliques, contract during forced expiration, forcing abdominal organs upward against the diaphragm and pushing more air out. In addition, accessory muscles, primarily the internal intercostals, help to compress the rib cage, reducing the volume of the thoracic cavity.