An interventional study of Concurrent Exercise Program and Usual Metabolic Rehabilitation Program in Obesity & Overweight and Post-bariatric Surgery, sponsored by Universidad Autónoma de Chile. Recruiting at 1 site in Chile. Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-09-25.
Sponsored by Universidad Autónoma de Chile · Not applicable, Interventional, and Treatment
This study aims to evaluate the effect of a 5-week concurrent exercise program (aerobic and resistance training) on muscle quality, body composition, functional response, and quality of life in individuals undergoing bariatric surgery.
This is a single-center, prospective, longitudinal, randomized controlled clinical trial with two parallel groups: an intervention group and a control group. A total of 87 adults aged 18 to 60 years who have undergone sleeve gastrectomy or Roux-en-Y gastric bypass and have a medical indication for metabolic rehabilitation will be recruited.
The intervention group will participate in a structured, semi-supervised concurrent exercise program for 5 weeks, consisting of two in-person sessions per week (10 sessions in total), whereas the control group will continue receiving usual kinesiology care and standard clinical management according to the institutional rehabilitation protocol at Clínica BUPA Santiago. All participants will be assessed at two time points: baseline, during the fourth postoperative week, and at week 7.
The primary outcome will be the change in rectus femoris muscle quality assessed by ultrasound (echo intensity). Secondary outcomes will include body composition (bioelectrical impedance analysis), functional response (One-minute Sit-to-Stand Test), and quality of life (Moorehead-Ardelt II questionnaire).
Additionally, adherence to the exercise program in the intervention group will be assessed as the percentage of attendance at supervised exercise sessions, and its association with the magnitude of changes in study outcomes will be explored.
The findings are expected to provide clinically relevant evidence regarding the effectiveness of exercise during the early postoperative period and to contribute to the optimization of metabolic rehabilitation strategies following bariatric surgery.
Bariatric surgery is an effective treatment for severe obesity; however, the early postoperative period is frequently associated with loss of lean body mass, reduced muscle strength, and functional decline, which may negatively affect recovery and quality of life. Physical exercise has been proposed as a key component of metabolic rehabilitation, although evidence regarding structured concurrent exercise programs initiated early after bariatric surgery remains limited, particularly with respect to muscle quality.
The aim of this study is to evaluate the effect of a 5-week concurrent exercise program on rectus femoris muscle quality in individuals undergoing bariatric surgery, compared with a control group receiving usual kinesiology care. Secondary objectives include evaluating changes in body composition, functional response, and quality of life, as well as exploring the association between exercise adherence and the magnitude of observed changes.
This is a single-center, prospective, longitudinal, randomized controlled clinical trial with two parallel groups (intervention and control). A total of 87 adults aged 18-60 years who have undergone sleeve gastrectomy or Roux-en-Y gastric bypass at Clínica BUPA Santiago and have a medical indication for metabolic rehabilitation will be recruited. Participants will undergo baseline assessment during the fourth postoperative week and will then be randomly allocated in a 1:1 ratio to the intervention or control group using a sequence generated and administered by an individual independent of the assessors and treating physical therapists.
The intervention group will participate in a structured, semi-supervised 5-week concurrent exercise program designed according to the FITT principle (Frequency, Intensity, Time, and Type of exercise). The program will combine aerobic and resistance training and will include two supervised in-person sessions per week (10 sessions in total) plus one complementary home-based session each week. Aerobic training will progress from continuous moderate-intensity exercise to interval training, whereas resistance training will progressively increase training volume for large muscle groups. Exercise intensity will be monitored using the Borg Rating of Perceived Exertion scale, and resistance loads will be individually adjusted according to each participant's clinical tolerance.
Participants allocated to the control group will continue receiving usual kinesiology care and standard clinical management according to the institutional metabolic rehabilitation protocol at Clínica BUPA Santiago. This program will also follow the FITT principle and will include two supervised sessions per week consisting of continuous aerobic exercise, targeted muscle strengthening, and static stretching, consistent with routine clinical practice, without the structured progression incorporated into the concurrent exercise program.
Following the 5-week intervention period, both groups will complete one week without supervised exercise sessions to minimize the acute effects of exercise on muscle measurements. Final assessments will be performed at week 7.
The primary outcome will be the change in rectus femoris muscle quality assessed by musculoskeletal ultrasound using echo intensity as the primary indicator. Secondary outcomes will include body composition assessed by bioelectrical impedance analysis, functional response assessed using the One-minute Sit-to-Stand Test, and quality of life assessed using the Moorehead-Ardelt II questionnaire.
Exercise adherence will be assessed exclusively in the intervention group as the percentage of attendance at supervised exercise sessions. The association between adherence and the magnitude of outcome changes will also be explored using a dose-response approach.
Statistical analyses will follow the intention-to-treat principle. The primary analysis will be performed using analysis of covariance (ANCOVA), with study group as the fixed factor and baseline values as covariates, adjusting for prespecified clinically relevant covariates when appropriate. Secondary outcomes will be analyzed using the same approach. Complementary analyses will include within- and between-group comparisons using parametric or non-parametric tests according to data distribution, estimation of effect sizes, and exploratory correlation and linear regression analyses to evaluate the association between exercise adherence and changes in study outcomes.
Exclusion Criteria
Participants allocated to the intervention group will complete a structured, semi-supervised concurrent exercise program during the postoperative period following bariatric surgery. Participants will enter the study during postoperative week 4 and undergo a baseline assessment before starting the intervention. The program will last 5 weeks and will include 10 supervised in-person sessions (2 sessions/week, approximately 60 minutes each) and one complementary home-based session per week. After completion of the intervention, participants will remain one week without supervised exercise sessions before the week 7 follow-up assessment.
Behavioral: Concurrent Exercise Program
Participants allocated to the control group will receive the usual metabolic rehabilitation program at Clínica BUPA Santiago. The rehabilitation program will follow the FITT principle (Frequency, Intensity, Time, and Type of exercise) and will include two supervised sessions per week for 5 weeks consisting of continuous aerobic exercise, targeted muscle strengthening, and stretching according to the institutional protocol. All participants will undergo baseline and week 7 assessments.
Behavioral: Usual Metabolic Rehabilitation Program
Concurrent physical exercise program of 5 weeks combining aerobic and resistance training in individuals undergoing bariatric surgery. The program includes two supervised in-person sessions per week (10 sessions total), each lasting approximately 60 minutes, and one recommended weekly home-based session guided by a prescribed exercise plan. Aerobic exercise is performed at moderate to high intensity, monitored using the Borg Rating of Perceived Exertion scale. Resistance training targets major muscle groups and is prescribed based on an estimated one-repetition maximum (1RM), with progression in volume and intensity according to individual tolerance and safety criteria. The program begins at postoperative week 4. After completing the 5-week intervention, participants undergo a 1-week period without supervised sessions before the post-intervention assessment.
Also known as: Concurrent Physical Exercise Program
Usual institutional metabolic rehabilitation program at Clínica BUPA Santiago based on the FITT principle (Frequency, Intensity, Time, and Type of exercise). The program includes supervised continuous aerobic exercise, targeted muscle strengthening, and stretching delivered twice weekly for 5 weeks according to the institutional clinical protocol.
Change in rectus femoris muscle quality (echo intensity; grayscale units 0-255)
Muscle quality will be assessed by ultrasound as echo intensity (mean grayscale value, 0-255) within a standardized region of interest, analyzed using ImageJ, at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in percent body fat (%)
Body composition will be assessed using bioelectrical impedance analysis (InBody S10) under standardized conditions before and after the intervention. Percent body fat (%) will be recorded at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in fat mass (kg)
Body composition will be assessed using bioelectrical impedance analysis (InBody S10) under standardized conditions before and after the intervention. Fat mass (kg) will be recorded at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in skeletal muscle mass (kg)
Body composition will be assessed using bioelectrical impedance analysis (InBody S10) under standardized conditions before and after the intervention. Skeletal muscle mass (kg) will be recorded at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in 1-minute Sit-to-Stand performance (1min-STST)
Functional response will be assessed using the One-minute Sit-to-Stand Test (1min-STST). The primary metric is the total number of completed repetitions in 60 seconds performed using a standard chair. Perceived exertion (modified Borg scale) may be recorded as a complementary measure.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Adherence to the exercise program (supervised in-clinic sessions)
Attendance rate to supervised in-clinic sessions at Clínica BUPA during the intervention. Adherence will be calculated as: adherence (%) = (number of attended sessions / 10) × 100. For descriptive purposes, adherence will be categorized as high (8-10 sessions; ≥80%), moderate (6-7 sessions; 60-79%), and low (0-5 sessions; \<60%). Adherence ≥80% will be considered clinically acceptable.
Time frame: During the 5-week intervention period (calculated at the end of the program based on attendance to the 10 supervised sessions).
Change in visceral fat area (cm²)
Body composition will be assessed using bioelectrical impedance analysis (InBody S10) under standardized conditions before and after the intervention. Visceral fat area (cm²) will be recorded at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in basal metabolic rate (kcal/day)
Body composition will be assessed using bioelectrical impedance analysis (InBody S10) under standardized conditions before and after the intervention. Basal metabolic rate (kcal/day) will be recorded at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in rectus femoris muscle thickness (cm)
ectus femoris muscle thickness (cm) will be assessed by ultrasound under standardized conditions at baseline and post-intervention. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in rectus femoris cross-sectional area (cm²)
Rectus femoris cross-sectional area (cm²) will be assessed by ultrasound under standardized conditions at baseline and post-intervention. Change will be calculated as Δ = post - pre
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in intramuscular fat infiltration assessed by ultrasound echo intensity (grayscale units 0-255)
Intramuscular fat infiltration will be assessed by musculoskeletal ultrasound using rectus femoris echo intensity (grayscale units 0-255) under standardized acquisition conditions. Images will be analyzed using ImageJ. Change will be calculated as Δ = post - pre.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of intervention and 1 week of rest).
Change in quality of life assessed by the Moorehead-Ardelt II questionnaire
Quality of life will be assessed using the Moorehead-Ardelt II questionnaire, a bariatric surgery-specific instrument that evaluates domains including self-esteem, physical well-being, social relationships, work, and sexuality. Total score (and domain scores, if applicable) will be compared before and after the intervention.
Time frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Plan to share: No — Individual participant data (IPD) will not be publicly shared to protect patient confidentiality. Only aggregated and anonymized results will be disseminated through scientific publications or presentations.
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