RÉSUMÉ
Background: To compare the acute and chronic effects of frequent, short physical activity (PA) bouts spread throughout the day to a time-matched intervention consisting in a single continuous daily bout of PA on glucose control and potential underlying mechanisms in adults at risk of developing type 2 diabetes (T2D). Methods: BURST2D is a single-center, parallel-group, randomized controlled trial, in which sedentary adults with overweight/obesity and pre-diabetes (18-45 y, BMI: 25-40 kg/m2, fasting glucose: 100-125 mg/dL or 2h glucose: 140-199 mg/dL or HbA1c: 5.7-6.4%) will be randomly assigned to one of two 3-month PA interventions: BREAK, nine bouts of 5-min brisk walking performed every hour for nine consecutive hours (45-min/d total), 5 days/wk; ONE, one continuous 45-min bout of brisk walking, 5 days/wk. Primary outcomes will be daily glycemic mean and variability, fasting glucose and HbA1c, postprandial plasma glucose and insulin, glucose kinetics, and content of skeletal muscle proteins related to insulin signaling and glucose uptake. Secondary outcomes will be whole-body insulin sensitivity, 24-h total substrate oxidation, postprandial triglycerides, daily PA and sedentary behavior (SB) patterns, knowledge and attitude towards PA and SB, barriers and facilitators to intervention compliance, self-perceived appetite, mood, and sleep. Outcomes will be assessed at baseline and after one month and/or three months of intervention. Conclusions: This study will establish the acute and chronic effects of breaking up SB, independent of increases in PA, on glucose control and underlying mechanisms in adults with pre-diabetes. Results will advance the science of T2D prevention. Trial registration: This study is registered with the ClinicalTrials.gov, registry number NTC05041491