Introduction: Sedentary behavior (SB) and insufficient physical activity (PA) interact to worsen physical fitness (PF), obesity-related complications and diseases (ORCD), and all-cause mortality in women with obesity. Replacing SB with low-intensity PA may improve PF and ameliorate ORCD, with potential lasting effects after bariatric surgery (BS). However, strong evidence on how PF influences BS outcomes and whether preoperative PA interventions can improve postoperative outcomes is lacking. The BARIMOV study aims to evaluate the effects of a structured sedentary behavior reduction program (SBRPro) on PF, investigate whether PF improvements influence BS outcomes, and explore potential mechanistic pathways by characterizing molecular adaptations in peripheral blood, skeletal muscle, and visceral adipose tissue (VAT).

Methods: BARIMOV is a prospective cohort study with five assessment time points. Adult women (≥18 years) with BMI 30-45 kg/m² scheduled for BS will be recruited (n = 72). At T0, participants will undergo a baseline assessment of PF - body composition, muscle strength, cardiorespiratory fitness - PA patterns, and ORCD screening. Participants will be instructed in the SBRPro and asked to maintain weekly PA diaries throughout the pre- and post-operative periods. At T1, adherence to SBRPro will be evaluated via diary review and PF reassessment, to enable participants' allocation into two adherence-based groups. At T2, during surgery, skeletal muscle and VAT biopsies will be collected for proteomic analysis to compare molecular adaptations of adherent and non-adherent groups. At T3 and T4, primary outcomes, including weight loss, body composition, ORCD, and quality of life (QoL), will be evaluated at 3±1 and 12±1 months postoperatively, respectively. Blood multiomics profiling will be performed at T0, T1, and T3 to explore dynamic changes in systemic metabolic pathways over time.

Conclusion: This study will determine whether PF improvement, achieved through structured SB reduction and PA engagement, is associated with better BS outcomes. By integrating clinical and molecular endpoints, the study will provide mechanistic insights into the pathways by which PF enhances BS outcomes and inform physical activity intervention strategies.

• Study Design and Participants BARIMOV will be a prospective cohort study designed to evaluate the effects of an SBRPro on BS outcomes in women and to explore the biological mechanisms underlying these effects. The study includes five predefined assessment timepoints: baseline (T0, 6±3 months before surgery), preoperative reassessment (T1, 2 weeks±3 days before surgery), intraoperative biopsies (T2), early postoperative reassessment (T3, 3±1 months after surgery), and final postoperative reassessment (T4, 12±2 months after surgery).
• Intervention Participants will be instructed to follow an online SBRPro program initiated 6±3 months before surgery. SBRPro provides standardized guidance on decreasing sedentary time and increasing regular PA, tailored to individual capabilities, delivered via mobile phone apps featuring messages, videos, and PA and exercise tutorials. The intervention will comprise 3 main phases.

Phase 1: Enrollment and Multidisciplinary Education (T0) All participants will attend a group educational session (40 minutes) delivered by a multidisciplinary team (bariatric surgeon, exercise physiologist, dietitian) addressing: 1) overall education about the BS clinical process and surgery procedures, risks, advantages and disadvantages; 2) a comprehensive education on SB harms and health risks, and benefits of PA across the pre- and post-operative period; 3) practical strategies for reducing sedentary time (e.g., breaking up prolonged sitting or interrupting extended bouts); 4) PA safety, proper exercise execution, PA intensity management and progression strategies; 5) nutritional education for preoperative fitness and postoperative recovery; and 6) distribution of written materials (flyers and booklets) summarizing key take home contents delivered at the session.

Phase 2: Structured Preoperative Sedentary Behavior Reduction Program (T0 to T1) Participants will be asked to engage in the SBRPro, which includes aerobic and strength activities, in compliance with current PA guidelines. Flexibility to adapt the PA and exercise modality, duration, and intensity based on individual preferences, physical capacity, and available resources (home-based, gym-based, online platforms, or combined approaches) will be provided.

Phase 3: Structured Postoperative Sedentary Behavior Reduction Program (T2 to T4) Participants will be asked to resume SBRPro activities within the first week post-BS, adjusting the program for postoperative individual restrictions. A progressive increase in daily PA will be encouraged. For resistance exercises, participants will be advised to avoid heavy loading of incision/staple lines and to progress from light to moderate resistance as tolerated. Given the postoperative vulnerability, remote counseling will be provided as needed to enhance safety. The same weekly PA diary-based monitoring will be requested.

Physical Activity Monitoring and Adherence Assessment SBRPro adherence will be assessed through a structured weekly PA diary using a simple online form. The form will collect self-reported data on average daily sedentary time (minutes per day), total time spent in light, moderate, and vigorous physical activity (minutes per week), and the number of days per week engaged in resistance training. The form will also include a subsection addressing PA satisfaction/enjoyment (5-point Likert scale: 1, nothing fun; 2, little fun; 3, indifferent; 4, fun; 5, very fun), and any barriers or adverse events encountered. This weekly assessment will take place from baseline (the moment of enrolment in the study) until up to 12 months after surgery. For primary analyses, adherence subgroups, determined from the weekly PA diary, will be classified as having either an active or a sedentary lifestyle according to the most recent World Health Organization criteria. Individuals will be classified as physically active if they accumulate at least 150 minutes of moderate-intensity physical activity per week, and as sedentary if they do not meet this threshold. Participants with a sedentary lifestyle will serve as the de facto comparison group. This will enable evaluation of whether differential engagement with the SBRPro is associated with distinct clinical and functional outcomes.

• Clinical and Functional Assessments PF evaluations that include changes in body composition, muscle strength, and CRF will be assessed to determine the effects of the SBRPro. Body composition [total weight (kg) and weight loss (absolute and % excess weight lost), fat mass (kg and %), lean mass (kg and %), muscle mass (kg and %)] will be measured via bioimpedance analysis (InBody 970 model, Biospace, Korea). Muscle strength (Kgf) will be assessed using handgrip (Jamar+, Lafayette Instrument Company, USA) and knee isometric strength tests (GripWise, Wisify Tech Solutions, Lda., Portugal). The estimated CRF (eVO2m) will be evaluated using the 2-minute step test (2MST). Changes in PA patterns between T0 and T1, and T2 and T3 will be subjectively measured using the language validated 24-hour movement questionnaire (QMov24h) and objectively measured PA, between T1 and T2, via accelerometry (ActiGraph wGT3X-BT model, Ametrics, USA), worn for 7 days, quantifying daily activity volume (steps, minutes of light, moderate, and vigorous activity), and sedentary time. The resolution or improvement of the ORCD and the health-related QoL will be assessed using the SF-12 (12-item Short Form Health Survey) validated questionnaire.
• Biological Sampling and Molecular Analyses Fasting blood samples will be collected at T0, T1, and T3. Plasma will be processed and stored at -80ºC for metabolomic profiling. Circulating metabolomic profiling will be performed using proton nuclear magnetic resonance (1H-NMR) spectroscopy to evaluate longitudinal systemic metabolic adaptations across time points. Molecular findings will subsequently be integrated with clinical and functional outcomes to explore potential mechanistic links between behavioral modification, tissue remodeling, and postoperative results.

During BS (T2), biopsies of abdominal skeletal muscle (transversus abdominis) and visceral adipose tissue (VAT) will be obtained under direct surgical visualization. Tissue fragments will be immediately processed and preserved at -80ºC for downstream proteomic analysis. Label-free quantitative proteomics, using the GeLC MS/MS approach, will be performed to identify differential protein expression patterns between adherence groups. Functional enrichment and pathway analyses will be conducted to characterize biological processes associated with preoperative SB reduction and PA engagement.

Inclusion Criteria:

• Adult women (≥ 18 years);
• BMI of 30-45 kg/m2;
• Scheduled for primary vertical sleeve gastrectomy or Roux-en-Y gastric bypass;
• Capacity to provide informed consent, adequate proficiency in the national language;
• Access to the internet and mobile phone communication.

Exclusion Criteria:

• Previous bariatric surgery or gastric surgical procedure;
• Physical incapacity or medical contraindications precluding physical fitness testing or participation (active cardiac disease, uncontrolled hypertension, severe joint disease);
• Pregnancy or breastfeeding;
• Inability to provide informed consent or comply with study procedures;
• Patients with type 1 or 2 diabetes mellitus.