A Comparison Between Two Different Conditions Of Breaking Up Sedentary Behaviour On Glucose Metabolism

INTRODUCTION: Sedentary behaviour is suggested a risk factor for various health outcomes, independent of the amount of subcomponents of physical activity. There is currently paucity of experimental studies comparing frequent breaks of sedentary time with one single long bout of exercise in an iso-caloric design. PURPOSE: to examine if breaking up sedentary behaviour with short five minutes’ bouts or one continuous 30-minute bout of vigorous intensity activity differentially affects metabolic risk markers compared with a control condition of prolonged sitting. METHODS: 12 healthy adults participated in a randomized cross-over design as follows;1) six hours of quiet sitting; 2) six hours of sitting, including five minutes exercise bouts (treadmill running) at 70 % of maximal oxygen uptake (VO2max) each hour; 3) continuous exercise at 70 % of VO2max, for 30 minutes followed by five hours and 30 minutes of sitting. Prior to each test, a fasting blood sample was collected and followed by a standardized meal consisting of 646 kilocalories. Blood samples were thereafter collected every hour. Maximal aerobic capacity was measured using indirect calorimetry and the running speed equivalent to 70 % of VO2max was determined by extrapolation following a submaximal steady state exercise test prior to the experiment. Each condition was separated by a 6-day wash-out period. RESULTS: There were no differences in insulin (mean (95 % CI); 1) 60704.8 (36352.4-79412.1) pmol · L-1 · 360 min; 2) 53375.7 (28787.8-71847.5) pmol · L-1 · 360 min; 3) 44827.3 (24853-67912.7) pmol · L-1 · 360 min), glucose (mean (95 % CI); 1) 105 (27.6-150) mmol · L-1 · 360 min; 2) 48.4 (-88.6-113.5) mmol · L-1 · 360 min; 3) 105.8 (49.3-171.6) mmol · L-1 · 360 min) and triglycerides (mean (95 % CI); 1) 41 (10.4-72.1) mmol · L-1 · 360 min; 2) 60.63 (30-91.5) mmol · L-1 · 360 min; 3) 38.22 (9.4-71.1) mmol · L-1 · 360 min) incremental area under curve between conditions. CONCLUSION: There is no effect of either breaking up sedentary behaviour each hour or performing 30 minutes of vigorous physical activity in one bout compared with prolonged sitting for six hours on glucose and lipid metabolism.