Effect of Inspiratory Muscle Training on Symptom Severity and Quality of Life in Non-Erosive Reflux Disease

The goal of this clinical trial is to learn if inspiratory muscle training (IMT) works to treat on clinical symptom severity and quality of life in patients with Non-erosive reflux disease (NERD). The main questions it aims to answer are: Does drug IMT lower the clinical symptom severity ? Does drug IMT improve quality of life? Researchers will compare high intensity IMT to a sham-IMT (a IMT device with no resistance) to see if IMT lower the clinical symptom severity and improve improve quality of life. Participants will perform the following protocol: The IMT protocol will consist of home-based high-intensity training using a Threshold IMT device: two sets of 30 breaths with a 1-minute rest, twice daily for 4 weeks. The study group will train at 60% of baseline maximum inspiratory pressure (MIP), with weekly adjustments based on modified Borg scores (4-6), while the control group will perform sham IMT without resistance.