Background: In gastroesophageal reflux disease (GERD), opposite to traditional 
medications which do not target the pathophysiological mechanism of GERD, manual 
diaphragmatic activation maneuver (MDAM) directly corrects the pathophysiological 
mechanism of GERD, as it strengthens/augments the anti-reflux barrier. Purpose: This 
study aimed to investigate the effect of MDAM on GERD patients' diaphragmatic 
excursion (DE), diaphragmatic thickness fraction (DTF), and 19-item Pittsburgh sleep 
quality index (PSQI). Methods: Thirty GERD sufferers were randomly assigned into two 
15-patient groups, the MDAM group (study group) and the control group. Both GERD 
groups received for-GERD-designed medical routine/care for 2 months. A 30-minute 
manual diaphragmatic activation maneuver was applied to the MDAM group only three 
times per week for 2 months. For all GERD patients in both groups, DE, DTF, and PSQI 
were the outcomes of this randomized GERD trial. Results: All outcomes (DE, DTF, and 
PSQI) of this GERD trial significantly improved in both GERD groups. The percent of 
change in GERD patients' DE, DTF, and PSQI of the MDAM group was 8.65, 19.56, and 
60.40%, respectively, and that in the GERD group that received only GERD routine 
medical care was 2.43, 5.80, and 34.82%, respectively. Conclusions: manual 
diaphragmatic activation maneuvers improve GERD in DE, DTF, and PSQI more than the 
other group who received only traditional medical care.