The lower esophageal sphincter (LES), surrounded by diaphragmatic muscle, prevents gastroesophageal reflux.

GERD occurs when these structures become incompetent allowing stomach acid and other stomach fluids travel back up into the esophagus .

GERD can be accompanied by a hiatal hernia, which occurs when part of the stomach has moved up from the abdomen into the chest.

Researches show that patients with GERD have a decreased diaphragm function. Therefore, practicing the diaphragm function by breathing exercise can play a role in treating GERD patients.