There have been limited strategies developed to improve cardiac dysfunction among type 2 diabetics, which continues to be the leading cause of mortality in this population. Therefore, a randomized trial was conducted to research the potential of high intensity intermittent training (HIIT) to improve cardiac structure and function in type 2 diabetes. A secondary outcome to measure the effectiveness of HIIT on liver fat and metabolic control was also explored.
Researcher Sophie Cassidy, PhD, and her partners analyzed data from 23 adults with type 2 diabetes controlled with diet or metformin. These individuals were assigned to HIIT for 12 weeks or standard care. Subjects in the exercise group were provided intense cycling sessions on 3 nonconsecutive days out of the week. Participants repeated intervals that gradually increased to 3 minutes 50 seconds. Participants were given 3-minute recovery between intervals, which included 90-second passive recovery, 60-seconds of band-resistance upper body exercises, and 30-seconds to arrange for the following interval.
The first training session was supervised, and each session thereafter was performed through mp3 voice recordings. Participants wore sensory armbands, and were monitored weekly for performance through phone calls and training diaries. Cardiac structure and function was measured using a MRI, liver fat was measured by H-magnetic resonance spectroscopy, and glucose by an OGTT both initially and at 12 weeks.
Researchers claim that during the 12-week period studied, the exercise group displayed cardiac changes evident by 12% increase in ventricular wall mass (P<0.05). In addition, the study also determined increased end-diastolic blood volume (P<0.01), improvement in systolic function, and improvement in left ventricular ejection fraction (P<0.05). A secondary outcome of liver fat reduction in the exercise group was evident by a reduction from 6.9% to 4.2%, which is a 39% reduction rate (P<0.05). Lastly, the HIIT intervention did not have any significant effect on fasting glucose or fasting insulin; nonetheless, it was noted that liver fat reduction was correlated to changes in HbA1C and 2-hour glucose.
Overall, authors conclude that this is the first study performed to show that exercise has some reversal effects on the early cardiac changes observed in type 2 diabetic patients. Furthermore, researchers claim that HIIT has benefit on both cardiac and glucose control, but the predominant efficacy is attributed to cardiac improvement. Although the concept of exercise and its benefits are not new, researchers believe that the conversation of HIIT in type 2 diabetic patients should be discussed at every opportunity.
- Researchers claim this study to be the first to reveal improvements in cardiac structure and function, as well as the most reduction in liver fat following an exercise intervention in type 2 diabetes.
- High intensity intermittent training has great potential to improve cardio-metabolic risk in patients with type 2 diabetes.
- Clinicians should consider HIIT as part of therapy in type 2 diabetics for improvement of cardiac function.
Cassidy, Sophie, et al. “High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type-2 diabetes: a randomized controlled trial.” Diabetologia (2015).