This randomized, single-blind, parallel-group clinical trial investigates whether a six-week supervised clinical Pilates exercise program improves reflux symptom severity, postural alignment, dynamic balance, sleep quality, depressive symptoms, anthropometric measures, and overall health-related quality of life in adults with gastroesophageal reflux disease (GERD). Participants attended 18 face-to-face sessions over 6 weeks (3 times/week) under physiotherapist supervision. Outcomes included reflux symptom scores (GERD-Q, FSSG), health-related quality of life (SF-36), sleep quality (Pittsburgh Sleep Quality Index), depression (Beck Depression Inventory), postural alignment (PostureScreen Mobile), dynamic balance (Y-Balance Test), and anthropometric circumferences (chest, sub-sternal, waist).

Design: randomized controlled, single-blind, parallel-group trial conducted at Istinye University Physiotherapy and Rehabilitation Application and Research Center (FIZYOTEM). Eligible adults (18-65 years) with a clinically confirmed diagnosis of gastroesophageal reflux disease and self-reported GERD symptoms for at least three months, who were physiologically able to participate in low-to-moderate intensity exercise, were enrolled. Allocation followed a computer-generated random sequence with concealed assignment to: (1) Clinical Pilates Group (PG): a progressive, posture-focused clinical Pilates program performed exclusively in the standing position to minimize intra-abdominal pressure, with no anterior trunk flexion or direct abdominal compression; (2) Control Group (CG): usual daily activity with no exercise intervention. The Pilates group completed 18 supervised face-to-face sessions across 6 weeks (3 sessions/week). Each session included a ~10-minute warm-up (Cleopatra, upper-extremity PNF patterns, Toy Soldier, Corkscrew, Chest Stretch), a main phase (Tic-Toc Arm Float, Bow & Arrow, Spine Twist, Footwork, Knee Lift & Aeroplane, Plié - Second to First - Moving Balance, Balance, Balance Plié with Arms), and a 5-10-minute cool-down/stretching phase. Progression across the 6 weeks was achieved by increasing repetitions (5 → 10) and active duration (5 s → 10 s → 15 s) while maintaining one set per exercise and a 30-second rest interval. To minimize gastric distension, sessions were scheduled at least 2 hours after a main meal or at least 30 minutes before eating. Assessments were performed pre- and post-intervention in fixed order with rest intervals. Reflux symptom severity was quantified using the Gastroesophageal Reflux Disease Questionnaire (GERD-Q) and the Frequency Scale for the Symptoms of GERD (FSSG). Health-related quality of life was assessed with the Short Form-36 (SF-36); sleep quality with the Pittsburgh Sleep Quality Index (PSQI); depressive symptoms with the Beck Depression Inventory (BDI). Postural alignment was analyzed using the PostureScreen Mobile application (anterior, posterior, right and left lateral views; sagittal and frontal translations and angulations). Dynamic balance was measured with the Y-Balance Test (anterior, posteromedial, posterolateral reach, bilateral). Anthropometric circumferences (chest, sub-sternal, waist) were measured with a standard tape. Statistical plan: distribution evaluated with the Shapiro-Wilk test; within-group changes assessed using paired-samples t-test or Wilcoxon signed-rank test as appropriate; between-group comparisons using independent-samples t-test or Mann-Whitney U test; categorical variables with chi-square test. Analyses were performed in IBM SPSS Statistics v25.0 with a two-tailed alpha of 0.05. Sample size was estimated a priori (G*Power 3.1) for a moderate effect (d=0.6), α=0.05, power=0.80, yielding 19 participants per group; post-hoc power for the primary outcome (GERD-Q) reached 0.96 (d=1.37). No external funding; no conflicts declared.

Inclusion Criteria:

• Age 18-65 years.
• Clinically confirmed diagnosis of gastroesophageal reflux disease (GERD).
• Self-reported GERD symptoms (heartburn, acid regurgitation, etc.) for at least 3 months prior to enrollment.
• Physiologically able to participate in low-to-moderate intensity exercise.
• Provision of written informed consent.
• Cognitive and psychosocial capacity to comply with the program.

Exclusion Criteria:

• History of upper gastrointestinal surgery (especially fundoplication).
• Achalasia or severe esophageal motility disorder.
• Endoscopic evidence of advanced esophagitis, Barrett's esophagus, or esophageal stricture (complicated GERD).
• Active peptic ulcer disease or inflammatory bowel disease.
• Uncontrolled hypertension, coronary artery disease, or severe pulmonary disease.
• Severe musculoskeletal disorders (advanced scoliosis/kyphosis, acute disc herniation, severe osteoarthritis) or vestibular balance disorders.
• Pregnancy or suspected pregnancy.

Outcome assessments and data analyses were performed by a researcher blinded to group allocation.