Purpose: Prediabetes is linked to several modifiable risk factors, in particular, physical activity participation. The optimal prescription for physical activity remains uncertain. This pilot study aimed to investigate the effectiveness of continuous moderate intensity (CON) versus high-intensity interval training (HIIT) in persons with prediabetes. Outcome measures included glycated hemoglobin (A1C), body composition, musculoskeletal and aerobic fitness.
Methods: Participants (n = 35) were recruited and screened using a questionnaire plus capillary blood point-of-care A1C analysis. After baseline screening/exclusions, 21 participants were randomly assigned to either HIIT or CON training three times per week for 12 wk. All participants also undertook resistance training two times per week. A1C, an oral glucose tolerance test, select measures of physical and physiological fitness were assessed at baseline and follow-up.
Results: There were no significant differences in improvements in select metabolic indicators to training between CON and HIT groups. Pooled participant data showed a mean reduction in A1C of 0.5% (95% confidence interval [CI] = 0.3%-0.7%), whereas β-cell function (%β) improved by 28.9% (95% CI = 16.5%-39.2%) and insulin sensitivity (%S) decreased by 34.8 (95% CI = 57.8%-11.8), as assessed by the Homeostatic Model Assessment. Significant reductions in waist circumference of 4.5 cm (P < 0.001) and a 20% (P < 0.001) improvement in aerobic fitness were also observed in both training groups.
Conclusion: The completion of a 12-wk exercise program involving both resistance training and either HIIT or CON training results in improved glycemic control, visceral adiposity, and aerobic fitness in persons with prediabetes.