Reducing Sedentary Time in Bariatric: The Take a STAND for Health Study

This research program aims to comprehensively investigate the clinical, physiological, metabolic, and molecular effects of reducing sedentary behavior in post-bariatric patients. To this aim, we will conduct a crossover trial and a randomized controlled trial. The crossover trial aims to unravel potential mechanisms underlying the metabolic, physiological and molecular effects of breaking up sedentary time with light-intensity physical activity versus carrying out the minimum amount of daily exercise at once and then remaining sedentary versus simply remaining sedentary throughout all sessions, in a well-controlled laboratorial condition. The 4-month parallel-group randomized controlled trials aim to investigate the feasibility and efficacy of a newly developed personalized intervention focused on replacing sedentary time with light- (or very light-) intensity physical activity in these patients. A multitude of gold-standard techniques will be applied to evaluate the effects of the intervention on several outcomes, including sedentary time (primary outcome), physical activity levels, clinical parameters specific to each condition, cardiometabolic risk factors, immune function, and health-related quality of life.

A newly developed personalized intervention focused on replacing sedentary time with light-(or very light-) intensity physical activity

The control group will receive all regular medical care and advice on healthy lifestyle including the promotion of recommended physical activity levels and health nutrition.

A 4-month parallel-group randomised controlled trial will be performed, in which patients post-bariatric surgery will be assessed at baseline pre-surgery (PRE-BAR), 3 months after surgery and pre-intervention (PRE-INT) and 4 months after intervention (POST). Moreover, a sub-sample of patients will perform a randomised crossover trial at baseline (PRE). Patients will complete three experimental sessions in a random manner, as follows: Prolonged sitting (SIT), in which participants engaged in prolonged sitting throughout an 5-h period and were instructed to minimize excessive movement; Exercise followed by prolonged sitting (EX), in which participants performed a 30-min moderate-to-vigorous exercise bout on a treadmill, subsequently, participants engaged in prolonged sitting as described for SIT; Light-intensity breaks (BR), in which participants completed a 3-min bout of light-intensity walking every 30 min of sitting throughout the experimental period.

Functional capacity will be assessed by Timed Up-And-Go, Time-Stands and handgrip tests. Fatigue will be assessed by fatigue severity scale and Chalder fatigue scale.

Cardiovascular and respiratory chemoreflex control will be assessed by hyperoxia and hypoxia protocol

Insulin sensitivity: fasting glucose and insulin; Lipid profile: Total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides

Inclusion Criteria: Women aged 20 to 50 years with BMI ≥ 35 kg / m2 and associated comorbidities, or BMI ≥ 40 kg / m2 who are about to undergo Roux-en-Y gastric bypass surgery at the Metabolic and Bariatric Surgery Unit of the Faculty of Medicine. - Exclusion Criteria: Exclusion criteria will involve sedentary time (sitting / reclining) <8 hours per day; anemia; hypothyroidism; current malignancy or history of cancer within the past 5 years; cardiovascular disease; neurological disorders; any physical disabilities that could hamper physical testing; and being physically active (i.e., participation in ≥ 150 minutes per week of moderate-to-vigorous physical activity in bouts of ≥ 10 minutes, or ≥ 75 minutes per week of vigorous-intensity physical activity). -