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Background and objectives: Pyruvate dehydrogenase kinase 4 (PDK4) is an enzyme involved in the regulation of glucose and fatty acid metabolism and homeostasis. The purpose of this study was to investigate effects of continuous exercise and resveratrol supplementation on insulin resistance and expression of PDK4 in the soleus muscle of elderly rats with type 2 diabetes.
Methods: After inducing diabetes in 42 old male rats (mean weigh: 250-300 g, aged about two years), the rats were randomly divided into six groups: healthy control, diabetic control, continuous exercise, supplementation, continuous exercise + supplementation and sham. The continuous exercise group was subjected to eight weeks of running, five sessions a week. Daily 20 mg/Kg body weight resveratrol supplementation was administered to the supplementation and supplementation + exercise groups. To evaluate insulin resistance, the HOMA-IR insulin resistance index was calculated as the product of insulin (μIU/mL) and glucose (mmol/L) divided by 22.5. Expression of the PDK4 gene in the soleus muscle was analyzed by RT-PCR. Data were analyzed with IBM SPSS Statistics 23 using one-way ANOVA and Tukey's post hoc test at a significance level of 0.05.
Results: Resveratrol alone or combined with continuous exercise significantly increased PDK4 expression and slightly decreased insulin resistance in the subjects.
Conclusion: Our results show that diabetes is associated with reduced PDK4 expression and increased insulin resistance. These effects can be effectively reversed in the soleus muscle of elderly diabetic rats by resveratrol supplementation alone or combined with continuous exercise.
 

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Background and objectives: Given the growing prevalence of obesity in children, the present study aimed to investigate effects of continuous and interval aerobic training on insulin resistance index and serum cortisol levels of obese girls.
Methods: The study was performed on 36 healthy girls aged 9-11 years with a body mass index (BMI) of higher than 85th percentile. The subjects were randomly divided into three groups of interval training, continuous training and control. The training groups performed exercises three days a week for eight weeks. The exercises were performed at 70% of VO2max in the first four weeks and at 80% of VO2max in the following weeks. Fasting blood samples were taken 72 hours before the first session and 72 hours after the last training session in order to measure levels of cortisol, glucose, insulin and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).Weight, BMI and body fat percentage were also measured by conventional methods. Data analysis was performed in SPSS 21 using paired t-test and one-way analysis of variance.
Results: The mean level of BMI and body fat percentage decreased significantly after the interval and continuous training, respectively (P<0.05). The HOMA-IR index did not change significantly in the study groups (P>0.05). The cortisol level increased slightly in the continuous training and control groups (P=0.075) and decreased insignificantly (P=0.131) in the interval training group. There was no difference between the training groups and the control group in terms of HOMA-IR and cortisol levels.
Conclusion: Insulin levels, HOMA-IR showed a decrease trend while a reasonable increase in cortisol level we showed in the continuous training group. BMI level and fat percentage decreased in two both training groups.

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Background: Omentin-1 plays an important role in insulin function. Despite numerous studies, the effect of interval training on this adipokine is still vague. This study aimed to elucidate the effect of high-intensity interval training (HIIT) on serum glucose, insulin, insulin resistance (IR), omentin-1 serum levels, and gene expression in the visceral adipose tissue in type 2 diabetic (T2D) rats.
Methods: In an experimental study, 20 male rats (8-10 weeks, weight: 250-270 g) were randomly divided into 2 groups: diabetic control (N=10) and diabetic training (N=10). The training protocol was 30 minutes of HIIT (1-min run, 2-min rest) performed 5 days a week for 4 weeks. Fasting blood glucose, insulin resistance, omentin-1 serum level, and gene expression were measured in the visceral fat 48 hours after the last exercise for both groups.
Results: The HIIT resulted in lower serum glucose and insulin resistance (P = 0.001), higher serum omentin-1 levels (P = 0.001), and higher visceral fat gene expression (P = 0.004) in the training group compared to the control group.
Conclusion: Lower serum glucose and insulin resistance and higher omentin-1 serum levels and gene expression in the training group can prove the effectiveness of HIIT training in T2D, although further research is required.