Vibrations added to aerobic training reduce insulin resistance in patients with nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide, and insulin resistance is a major contributor to the development of fatty liver disease. Previous studies have shown that treating insulin resistance can be achieved through aerobic or resistive exercise training. However, it is not clear what training protocol could be the most effective in NAFLD. Especially that most patients cannot participate in training regularly due to low physical efficiency. In recent years, whole-body vibration (WBV) has been adopted as a form of physical training recommended for weakened patients. WBV has also been shown to selectively stimulate larger alpha motor neurons to activate muscle, producing more power in less time with less energy expenditure. Therefore, Turkish scientists compared the effects of aerobic training or aerobic training with WBV on selected metabolic traits and quality of life of NAFLD patients. Following the 8-week individualized exercise program, the following were observed:

• a significant decrease in insulin resistance (Homa-IR) only in the WBV group (-2.36 in the WBV group vs 0.52 in control),
• a significantly greater (desired) decrease in serum aspartate transaminase after aerobic training without WBV (-4.00 IU/L in the group with WBV vs -14.81 IU/L in control),
• improved all domains of well-being (quality of life) in both groups.

Prepared on the basis of:

Impact of aerobic training with and without whole-body vibration training on metabolic features and quality of life in non-alcoholic fatty liver disease patients. Çevik Saldiran T, Mutluay FK, Yağci İ, Yilmaz Y. Ann Endocrinol (Paris). 2020 Oct;81(5):493-499.

Study population

Patients 18 to 65 y.o. with imaging confirmed NAFLD. Thirty two of the 76 patients were randomly assigned to two study groups.

Test procedure

Patients followed an 8-week individualized exercise program, randomized between aerobic training with or without WBV. As a standard, in the assessment of the physiological adaptation occurring during aerobic training, the maximum oxygen consumption (index of aerobic capacity) is being analyzed. Here it was assessed by cycling to exhaustion on a bicycle ergometer. The training was performed at 60-80% heart rate load for 165 minutes/ week. The assessment of steatosis and fibrosis, including transient elastography (FibroScan) was performed, as well as biochemical analysis of metabolic features, and quality of life in the SF-36 survey.

Use of vibration in the study

WBV was delivered during 15 min exercises on a vibration platform (vertical-sine; Power Plate® Pro5; Netherlands). The vibration amplitude was 2-4 mm, and the frequency was 30 Hz. Study participants rested for 60 seconds between exercises.

Results

After aerobic training with WBV, a significantly reduced insulin resistance was observed on the basis of the Homa-IR index (-2.36 ± 5.15 in the group with WBV vs 0.52 ± 2.68 in the group without WBV; P: 0.049). On the other hand, in aerobic training without WBV, a significantly greater (desired) decrease in serum aspartate transaminase was observed (-4.00 ± 5.58 IU/L in the group with WBV vs -14.81 ± 17.45 IU/L in the group without WBV; P: 0.029). There were no significant differences between the groups in other metabolic features. All domains of well-being in the quality of life survey improved in both groups.

Comment

The presented results indicate that, by reducing insulin resistance, WBV can usefully be added to aerobic training, positively acting on the reduction of this key pathogenic (in hepatocyte steatosis) factor. However, WBV added to aerobic training, compared to non-vibration aerobic training, did not provide much benefit in terms of improving metabolic properties other than insulin resistance or quality of life. Moreover, the addition of WBV to aerobic training was not an advantage in terms of liver enzymes as it resulted in a much less desirable decrease in aspartate aminotransferase than did aerobic training without vibration. Nevertheless, the significant and beneficial effect of WBV on insulin resistance suggests the need for further research on the use of WBV in the treatment of NAFLD, especially taking into account long-term training programs that may bring even better results.

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