This 2016 trial tested the impact of high-intensity interval training (HIIT) on markers of cardiometabolic function in diabetics.
Twenty-eight diabetics (mean age: 59-61; mean diabetes duration: 4-5 years) were randomized to 12 weeks of HIIT or standard care. Twelve subjects in the HIIT group and 11 controls completed the trial. The HIIT group was prescribed three cycling sessions per week for 12 weeks. Each session consisted of a warm-up followed by two- to three-minute intervals (progressing over 12 weeks) at a 16-17 Borg Rating of Perceived Exertion (RPE) or “very hard” difficulty level.
HIIT subjects saw significant increases in a variety of markers of cardiovascular health. Left ventricular mass, end-diastolic blood volume, stroke volume, and left ventricular ejection fraction all increased while peak torsion decreased. Collectively, these outcomes suggest subjects experienced healthful regeneration of cardiac muscle tissue and improved cardiac contractile capabilities, as well as reversal of certain forms of cardiovascular degeneration associated with Type 2 diabetes.
Figure 4: Effect of HIIT vs control on (a) left ventricular mass, (b) diastolic filling rate and (c) peak torsion. White bars, control; black bars, HIIT. Values are means ± SEM. *Significant difference baseline vs post-treatment (p < 0.05). †Significant difference between-group interaction (p < 0.05)
The same subjects also showed a 39% decrease in mean liver fat content, with four of the 11 subjects in the HIIT group seeing a reduction from clinically significant liver fat levels to “normal” liver fat. There was, however, no impact on fasting glucose or insulin.
In sum, this trial found 12 weeks of HIIT improved cardiac function and significantly reduced liver fat content in diabetic subjects.
High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes