Cardiometabolic response to a single high-intensity interval exercise session versus breaking up sedentary time with fragmented high-intensity interval exercise

This study compared the effects of interrupting prolonged sedentary time with high-intensity physical activity (SED-ACT), a volume and duration-matched high-intensity interval exercise session followed by prolonged sedentary time (HIIE), and prolonged uninterrupted sedentary time (SED) on postprandial glucose, insulin and triglyceride concentrations. Twelve sedentary and inactive, but otherwise healthy, adults completed three, 6.5 h conditions in an incomplete counterbalanced order. During SED, participants sat continuously. For HIIE, participants completed 10 x 60 s cycling bouts at 90% maximum oxygen update (V̇O2max) with 1 min active recovery between bouts. In SED-ACT, 60 s cycling bouts at 90% V̇O2max were completed every 30 min (10 times in total) with 30 s of active recovery immediately before and after. Standardised meals were consumed at 0 h and 3 h and capillary blood samples were collected fasted and every 30 min. Compared with SED, postprandial glucose incremental area under the curve (iAUC) was significantly lower in SED-ACT by 1.91 mmol/L∙6.5 h (p=0.022) and triglyceride iAUC was significantly lower in HIIE by 1.02 mmol/L∙6.5 h (p=0.030). Interrupting sedentary time with high-intensity physical activity can lower postprandial glucose concentrations, whereas a HIIE session can lower postprandial triglyceride concentrations.