Purpose: We investigated if a bout of HIIE is more efficacious at reducing postprandial hyperglycemia than an isocaloric bout of MICE.
Methods: Nineteen healthy physically active individuals (21% women) completed three trials in a randomized order: i) HIIE cycling consisting of 5 bouts of 4 min at 83 ± 9% of subjects' maximal oxygen consumption (V˙O2 MAX) with active recoveries at 53 ± 8% for a total of 50 min; ii) MICE cycling at 65 ± 8% of V˙O2 MAX for 50 min, and iii) CONTROL no exercise. All trials were followed by a standard oral glucose tolerance test (OGTT) ingesting 74 grams of glucose traced with 1 gram of uniformly labeled [13C]-glucose. Plasma glucose and insulin concentrations, and plasma glucose kinetics ([6,6 2H2] glucose infusion) were measured before, during exercise, and during the OGTT. Insulin sensitivity was estimated by the Matsuda index (ISI). Energy expenditure and carbohydrate oxidation (CHOxid) were monitored.
Results: At rest, blood glucose, insulin concentrations, and CHOxid were similar in all three trials. During exercise, energy expenditure was similar in HIIE vs MICE (548 ± 131 vs 560 ± 125 kcals; p = 0.340). However, CHOxid, plasma glucose concentration, and its rates of appearance in plasma (Ra) were higher in HIIE vs MICE (Ra glucose 34.3 ± 9.8 vs 28.9 ± 6.8 μmol·kg-1·min-1; p = 0.021). During the OGTT, plasma glucose and insulin concentrations were lower, and insulin sensitivity higher in HIIE vs CONTROL (ISI MATSUDA; 12.4 ± 4.7 vs 10.8 ± 4.7 au; p = 0.007). Exercise delayed blood incorporation of [13C]-glucose into blood (p = 0.023). Early during the OGTT, glucose clearance rates were higher in HIIE vs CONTROL (7.1 ± 3.1 vs 5.5 ± 3.0 mL·kg-1·min-1; p = 0.015).
Conclusions: HIIE is more effective than MICE to reduce hyperglycemia and hyperinsulinemia after glucose ingestion. HIIE improves glycemic control by increasing splanchnic glucose retention and glucose clearance rates.
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