Document Type : Original Article
Authors
1
Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan,
2
Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran
3
Department of Physiology, School of Medicine Isfahan University of Medical Science, Isfahan, Iran.
Abstract
Background and Objective: Diabetes mellitus is a common and lifelong health-threatening disease that affects vital organs such as the heart, kidneys, liver, and central and peripheral nervous systems by disrupting glucose metabolism and energy homeostasis. Exercise is one of the important interventions for reducing complications of diabetes, including cardiomyopathy, which produces different effects depending on the type of exercise program. In this study, the effect of 8 weeks of high-intensity interval training on a treadmill on changes in blood glucose, weight, and fibrosis indices in the heart tissue of diabetic rats was investigated.
Materials and Methods: 28 male 8-week-old Wistar rats weighing approximately 200±50 grams were divided into four groups: 1. Control, 2. Exercise, 3. Diabetes, and 4. Diabetes + Exercise. Diabetic groups received a single dose of streptozocin intraperitoneally. The exercise groups began progressive interval running on a treadmill at 85% of maximum speed for 8 weeks, so that the intensity of activity increased by 5% each week until the fifth week, and the activity speed remained constant in the final 3 weeks. The duration of activity also increased from 38 minutes in the first week to 60 minutes in the eighth week. Active rest intervals between high-intensity exercise intervals were 1 minute and at a speed of 10 m/min. Fasting blood glucose and weight changes were recorded before diabetes induction, and 3, 5, and 8 weeks later. At the end of the training sessions, the expression of TGF-B1/SMAD-4 genes was evaluated by qRT-PCR by extracting heart tissue. SPSS software and one-way ANOVA statistical method were used to analyze the gene expression findings, and the analysis of variance (4x4) design was used to examine changes in weight and blood glucose. Finally, the findings were evaluated at a significant level (p≤0.05) using Tukey's post hoc test.
Results: The diabetic groups showed increased blood glucose and fibrotic gene expression compared to healthy groups. Additionally, the weight change pattern showed a decreasing trend compared to healthy groups and also compared to pre-disease conditions. However, exercise in diabetic rats caused significant improvement in blood glucose from the fifth week after disease onset. Weight recovery compared to the non-exercised diabetic group was also observed in the Diabetes+Exercise group. Furthermore, expression of fibrotic genes TGF-β1/SMAD-4 was significantly reduced in this group. However, there remained significant differences in the examined factors between healthy and diabetic groups (p≤0.05).
Conclusion:
Although longer exercise duration would likely have greater effects on improving diabetes-related complications, 8 weeks of high-intensity interval training can be effective in improving cardiac fibrosis indices in diabetic rats and, by controlling glucose metabolism and weight homeostasis, can help improve disease-related disorders.
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