Effect of frequent interruptions of sedentary time on nutrient metabolism in sedentary overweight male and female adults

International audienceOBJECTIVE: This study compared 24-h nutrient oxidation responses between a sedentary condition (SED) and a condition where short 5-min bouts of moderate-intensity physical activity were performed hourly for 9 consecutive hours over 4-d (MICRO). To determine whether any shifts in fuel use were due solely to increases in energy expenditure we also studied a condition consisting of a single isoenergetic 45-min bout of moderate-intensity exercise (ONE). METHODS: Twenty sedentary overweight or obese adults (10M/10F; 32.4+/-6.3 years; BMI, 30.6+/-2.9kg/m(2)) completed all three conditions (MICRO, SED, and ONE) in a randomized order. Each condition consisted of a 3 d free-living run-in followed by a 24-h stay in a whole-room calorimeter to measure total energy expenditure (TEE) and substrate utilization. Dietary fat oxidation was also assessed during the chamber stay by administering a [1-(13)C] oleic acid tracer at breakfast. Energy intake was matched across conditions. RESULTS: Both MICRO and ONE increased TEE relative to SED resulting in a negative energy balance. HOMA-IR improved in both activity conditions. MICRO increased 24-h carbohydrate oxidation compared to both ONE and SED (p