Concurrent Exercise Effects in Post-Bariatric Patients (BAR-EX)

September 22, 2026 updated by: María José Pabst, Universidad Autónoma de Chile

Effect of a Concurrent Exercise Program on Muscle Quality, Body Composition, Functional Response, and Quality of Life in Individuals Undergoing Bariatric Surgery: Protocol for a Randomized Controlled Clinical Trial

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

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.

Study Type

Interventional

Enrollment (Estimated)

87

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Chile
    • Santiago Metropolitan
      • Santiago, Santiago Metropolitan, Chile, 7820830
        • Recruiting
        • Clínica BUPA, Santiago
        • Contact:
        • Contact:
        • Principal Investigator:
          • Tomás Vergara Soria, Kinesiólogo

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria

  • Adults aged 18-60 years.
  • Participants eligible for the institutional PAD (Pago Asociado a Diagnóstico) bariatric surgery program with medical indication for metabolic rehabilitation.
  • Undergoing sleeve gastrectomy or Roux-en-Y gastric bypass at Clínica BUPA Santiago.
  • Medical indication for metabolic rehabilitation.
  • Able and willing to provide written informed consent.

Exclusion Criteria

  • Type 1 diabetes mellitus or type 2 diabetes mellitus with severe complications (including stage G4-G5 nephropathy, severe autonomic neuropathy, or high risk of exercise-related hypoglycemia).
  • Severe musculoskeletal disorders limiting participation in the exercise program.
  • Acute cardiovascular event within the previous 3 months or medical contraindication to supervised exercise.
  • Severe cardiorespiratory disease or dyspnea at rest or with minimal exertion.
  • Dependence on supplemental oxygen.
  • Bariatric surgery complications (e.g., leak, bleeding, stenosis, or intra-abdominal abscess).
  • Liver failure, kidney failure, or any other clinical condition compromising safe participation in the exercise program.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Concurrent Physical Exercise Program

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

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.

Other Names:
  • Concurrent Physical Exercise Program
Active Comparator: Usual Metabolic Rehabilitation 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

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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in rectus femoris muscle quality (echo intensity; grayscale units 0-255)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in percent body fat (%)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in fat mass (kg)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).
Change in skeletal muscle mass (kg)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
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)
Time Frame: During the 5-week intervention period (calculated at the end of the program based on attendance to the 10 supervised 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.
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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
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)
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of intervention and 1 week of rest).

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.
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
Time Frame: Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

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.
Baseline (pre-intervention) and 7 weeks after baseline (after 5 weeks of exercise and 1 week of rest).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Universidad Autónoma de Chile

Collaborators

Clinica Bupa Santiago

Investigators

  • Principal Investigator: María José Pabst Pérez, MSc, Universidad Autónoma de Chile
  • Study Chair: Luis Astete, MSc, Universidad Autónoma de Chile
  • Study Chair: Nicolas Arancibia Ramirez, Kinesiólogo, Clinica Alemana
  • Study Director: Rosario Alonso Domínguez, PhD., Universidad de Salamanca. España
  • Study Director: María de la Luz Tocino, PhD., University of Salamanca
  • Study Director: Matias Otto Yañez, PhD., Universidad Autónoma de Chile. Chile
  • Study Chair: Paloma Lillo, MsC, Universidad Silva Henriquez
  • Study Chair: Carla Martinez Dominguez, Kinesióloga, Clinica Bupa Santiago
  • Principal Investigator: Tomás Vergara Soria, Kinesiólogo, Clínica BUPA Santiago
  • Study Chair: Sebastian Barrios Valenzuela, Kinesiólogo, Clínica BUPA Santiago
  • Study Chair: Erika Troncoso, MsC, Clinica las Condes
  • Study Chair: Karen Castañeda Lavin, MsC, University of Americas - Chili

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 11, 2025

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 31, 2028

Study Registration Dates

First Submitted

November 14, 2025

First Submitted That Met QC Criteria

February 17, 2026

First Posted (Actual)

February 20, 2026

Study Record Updates

Last Update Posted (Actual)

September 25, 2026

Last Update Submitted That Met QC Criteria

September 22, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CEC CBS /4-2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

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.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe