Effects of Different Dosages of Interval Training on Glycemic Control in People With Prediabetes: A Randomized Controlled Trial.

High-intensity interval training (HIIT) has been used as an alternative to moderate-intensity exercise training. Research has shown that HIIT produces better effects on glycemic control and hence the cardiometabolic risk in prediabetes. This randomized controlled trial was conducted to compare the effect of low-volume HIIT (LV-HIIT) with high-volume HIIT (HV-HIIT) on A1C and fasting blood glucose (FBG) in overweight adults with prediabetes. The trial included 60 young adults with prediabetes (32 male, 28 female). Subjects were randomly assigned to one of three equal-sized groups ( = 20): an LV-HIIT group (10 × 1-minute intervals at an interval intensity of ∼90% HR on a treadmill separated by 1 minute of easy recovery, with total exercise of 25 minutes/session), an HV-HIIT group (4 × 4-minute intervals at 90% of HR with 3 minutes of active recovery at 70% of HR between intervals, with total exercise of 40 minutes/session), and a control group (no exercise intervention). Exercise programs consisted of 3 sessions/week for 12 successive weeks. All participants followed a low-calorie diet for the 12-week intervention period. A1C and FBG were measured before and at the end of the 12-week trial. There were statistically significant effects on A1C and FBG from both exercise interventions ( <0.05). LV-HIIT and HV-HIIT significantly reduced A1C and FBG; however, HV-HIIT yielded a greater reduction in A1C than LV-HIIT (26.07 vs. 14.50%) and in FBG (17.80 vs. 13.22%) after exercise training, respectively. HIIT was found to be effective for glycemic control in prediabetes, with HV-HIIT being more effective than LV-HIIT in reducing A1C, FBG, and progression to type 2 diabetes in young adults with prediabetes.