Clinical Research Directory

Adherence to an Exercise Program and Pre- and Post-Changes After Bariatric Surgery

This study will examine within-subject (pre-post) changes in muscle quality, body composition, and functional response following a concurrent exercise program (aerobic + resistance training) in individuals after bariatric surgery. This is a single-center, prospective, longitudinal, quasi-experimental study with a one-group pre-post design. Men and women aged 18 to 60 years who have undergone sleeve gastrectomy or gastric bypass at BUPA Clinic Santiago, are PAD voucher beneficiaries, and have a medical indication for metabolic rehabilitation will be included. Participants will enter the study from postoperative week 4, when the baseline assessment will be performed and the program will begin. The intervention will consist of a 5-week supervised program delivered as two in-person sessions per week (10 sessions in total), each lasting approximately 60 minutes; additionally, participants will be prescribed one autonomous home-based session per week guided by an exercise plan provided by the responsible professional (as a complementary recommendation, not systematically recorded for adherence calculation). After the program, a 1-week period without supervised sessions will be observed, and the final assessment will be performed during the following week. Therefore, outcomes will be measured at two time points: baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest). Adherence will be assessed exclusively as the attendance rate to the 10 supervised in-clinic sessions during the 5-week intervention period, calculated as: adherence (%) = (attended supervised sessions / 10) × 100; for descriptive purposes, adherence will be categorized as high (≥80%), moderate (60-79%), or low (\<60%). Exploratory analyses will examine the association between adherence (%) and the magnitude of pre-post changes in primary outcomes using multivariable linear regression models, adjusting for weight change during the intervention period (Δweight = post-intervention weight - baseline weight). Muscle quality will be assessed using musculoskeletal ultrasound of the rectus femoris (Philips Lumify) with ImageJ image analysis, including thickness measures and parameters related to fat infiltration/echo intensity and area according to a standardized protocol. Body composition will be assessed by bioelectrical impedance analysis (InBody S10). Functional response will be measured using the One-minute Sit-to-Stand Test (1min-STST), with vital signs and perceived exertion (modified Borg scale) recorded as appropriate. Quality of life will be assessed as a secondary outcome using the Moorehead-Ardelt II questionnaire. The expected results will provide clinically relevant evidence on within-subject changes and on the association between adherence to a concurrent exercise program and muscle-related outcomes, supporting optimization of postoperative metabolic rehabilitation after bariatric surgery.

Glucagon-like Peptide 1, Glucose Metabolism and Gastric Bypass

The overall goal of this project is to understand the mechanisms by which gastric bypass surgery improves glucose metabolism. The central hypothesis guiding this project is that the reconfiguration of intestinal transit with the Roux-en-Y will increase the release of insulinotropic GI hormones, termed incretins that improve insulin secretion and glucose metabolism. The study is divided into three specific aims. 1. To determine the role of incretin hormones on insulin secretion in patients with gastric bypass surgery using intravenous-oral hyperglycemic clamp. 2. To compare incretin effect and glucose tolerance among patient who suffer from hypoglycemia after RYGB and asymptomatic surgical and non-surgical individuals. 3. To quantify the contribution of GLP-1 to incretin effect enhancement following surgery.