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.