Final answer:
Patients are usually advised to exhale and hold their breath when a barium enema tube is being inserted to help relax the muscles for easier tube insertion.
Step-by-step explanation:
When inserting a barium enema tube, it is often recommended for patients to exhale and hold their breath. This action can help in relaxing the muscles and can facilitate the easier insertion of the tube. During the process of exhaling, the diaphragm relaxes, moving upward and decreasing the volume of the thoracic cavity, which may minimize discomfort. Following the healthcare provider's breathing instructions is important for the safety and comfort of the individual during this procedure.