CrossFit | High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes

High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes

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ByCrossFitJuly 15, 2019

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

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.

Comments on High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes

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RAPHAEL SIRTOLI
July 23rd, 2019 at 2:58 pm
Commented on: High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes

Although the study boasts statistically significant differences between groups, like reduction in HbA1c, 2h glucose and glucose AUGC, the magnitude of improvements stay within 1 SD of the measure. This makes it hard to take identify those as a 'real changes'


the change in liver fat and cardiac function is more impressive and a sturdy result. it seems unlikely that HIT will halt the progression but it may slow it down. to reliably reverse liver fat a combination of fasting and/or some kind of low-carb diet devoid of seed oils is preferred. HIT may be a nice adjunct

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Benjamin Allen
July 16th, 2019 at 5:42 pm
Commented on: High intensity intermittent exercise improves cardiac structure and function and reduces liver fat in patients with type 2 diabetes

The study reads with some interesting highlights. First - "No adverse events were recorded", safety being paramount in training a diseased population, dosing them with high intensity served efficaciously to move the meter further right on the sick-well-fit continuum without injury. Second - "There was no effect of HIIT on whole body fat mass but within-group comparison revealed a reduction in visceral adipose tissue"..."HIIT elicited a 39% relative reduction in liver fat so that four patients in the exercise group moved from having clinically significant liver fat to within ‘normal’ limits", though this speaks to the power of high intensity exercise, it shows one of the most lacking and critical issues in a majority of research today. The patients were instructed "to continue their normal routine and care for 12 weeks and not to change medication, habitual physical activity, diet or body weight." This facilitates an easy research control measure, but the absence of nutrition protocol severely blunted the effects of an otherwise fruitful study. The next step to amplify effects would simply be to 'eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar. Keep intake to levels that will support exercise but not body fat." CFJ Oct.2002. This simple remedy alone would have exponential effects on results and research application.

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Clarke Read
July 21st, 2019 at 4:29 am

Benjamin, your points here are spot-on, and most importantly speak to how this intervention could be applied clinically today, based on existing evidence.


The public health importance of fatty liver disease could, by this point, hardly be overstated. Not only is it shockingly prevalent, affecting millions to tens of millions of Americans depending on your definition, but it contributes directly to the development of just about every other metabolic disease discussed on these pages. In light of a complete lack of pharmaceutical treatment options, you are right that any intervention able to reduce liver fat content is worth paying attention to.


At the same time, you are right to argue its effects are almost certainly greater in concert with diet. HIIT had particularly compelling benefits in this study, and probably improves cardiac function in ways diet cannot, but studies on low-carb, low-sugar, ketogenic and/or fasting-based diets have shown as great or greater improvements in liver fat content. I would reckon these diets, combined with HIIT, could rapidly resolve fatty liver disease even in patients with high baseline fat content.


It's exciting to think we actually may have a roster of options to tackle this condition, both to provide patients and clinicians with a wider variety of tools and to more effectively tackle treatment-resistant cases.

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