Short-Term Interval Training Increases Fat Utilization During Exercise in Adults With Prediabetes

Abstract

PURPOSE: Individuals with prediabetes have impaired fat metabolism. Interval exercise is thought to lower type 2 diabetes risk, but the mechanism is unclear. We tested the hypothesis that interval training would enhance fat oxidation during exercise and relate to lower disease risk to a greater extent than continuous exercise training. METHODS: Thirteen obese, sedentary adults with prediabetes (Age: 57.9±2.2y, BMI: 34.5±1.4 kg/m2, VO2max: 21.1±1.2 mL/kg/min, FPG: 100.1±2.1 mg/dL, 2-hr glucose: 147.7±8.1 mg/dL) were screened using a 75g OGTT. Subjects were randomized to 12 days of interval (INT, n=7; 3min 90%HRmax, 3min 50%HRmax) or isocaloric continuous (CONT, n=6; 70%HRmax) cycle ergometry exercise for 60 min/d. Body weight, VO2max, and substrate oxidation via indirect calorimetry during exercise at the same absolute (30W) and relative (70%HRmax) intensities were measured before and after training. Data were analyzed using a 2-way mixed model ANOVA and Pearson’s correlation, and reported as mean±SEM. RESULTS: Although there was no statistical change in body weight, VO2max increased after both INT and CONT training (P=0.05). Exercise training also increased fat oxidation at 30W (P=0.02) and 70%HRmax (P=0.03). INT training tended to increase fat oxidation more than CONT at 30W (+0.07±0.02 vs. +0.03±0.03 g/min, P=0.22) and 70%HRmax (+0.11±0.03 vs. +0.03±0.04 g/min, P=0.17), although these did not reach statistical significance. The rise in fat oxidation during exercise at 70%HRmax correlated with decreased body weight after training (r=-0.69, P=0.01). CONCLUSIONS: Short-term INT training increases fat oxidation during exercise in people with pre diabetes. This preliminary change in fat metabolism is associated with decreased body mass and may contribute to lower diabetes risk.