What process is capable of increasing both intrathoracic and intra abdominal pressure?

Valsalva maneuver

Explanation:

Valsalva's maneuver is an attempt to exhale against a closed airway. It can be used to clean the ears unintentionally during cough or bowel movement or as a diagnostic or treatment aid. This maneuver can increase intrathoracic and intra-abdominal pressure, regardless of whether the individual is crouching or sitting down.

To perform this maneuver, you should take a deep breath, close your mouth and pinch your nose with your thumb and index finger, and try to exhale gently, keeping your cheek muscles tight, not allowing them to lower.

nucleus

would be most reasonable answer tbh