جستجوی مقالات مرتبط با کلیدواژه « high-intensity training » در نشریات گروه « پزشکی »

During exercise, angiogenesis occurs in active skeletal muscle; however, little is known about potential mechanisms for improving this adaptation. This study aimed to investigate a period of interval training on chemokine gene expression and its effect on vascular endothelial growth factors in male adult rats.

In this study, 24 rats were divided into three groups (n=8 in each): high-intensity training (HIT), low-intensity training (LIT), and control groups. HIT and LIT groups were trained for eight weeks (five days per week). The exercise program in the HIT group consisted of running on a treadmill for 8 min with 85-90% VO2max intensity and 2 min with 50-60% VO2max intensity. The LIT group exercise program consisted of running on a treadmill for 8 min with 55-60% VO2max intensity and 2 min with 45-50% VO2max intensity. The control group had no training. The expression of chemokine and vascular endothelial growth factor genes was measured in soleus muscle. The data were analyzed using one-way ANOVA and Tukey post hoc test. Statistical differences were considered significant at P<0.05.

The results of this study, showed that the expression levels of chemokine and vascular endothelial growth factor gene in the HIT group were significantly higher than that in the control group (P=0.01, P=0.04), while the levels of chemokine and vascular endothelial growth factor in the LIT group were not significantly different from those in the control group (P=0.2, P=0.1).

According to the results of the present study, it seems that high-intensity exercises can be more effective than low-intensity exercises in increasing angiogenesis caused by the increase of chemokine that in turn depends on vascular endothelial growth factor levels.

The liver is one of the main and major organs of the body, which with the help of various enzymes is of special importance in regulating hormonal activities and metabolism, during rest, training, and returning to the original state of sports activities. Under normal circumstances, the liver and kidneys receive 27% and 22% of circulating blood, respectively, but as a result of heavy training, the blood flow to the liver and kidneys decreases to 5% and 3%, respectively. Prolonged reduction in blood flow to the liver and kidneys may have detrimental consequences, of which fatigue observed as a result of the constant sub-maximal activity is part of it. The liver is also one of the most sensitive tissues targeted by training-induced oxidative stress. Sports science coaches and professionals are working to find ways to reduce the effects of strenuous training and increase the effectiveness of training programs over a limited period. The liver has different functions in the body and different roles are considered for it. Metabolism, control of glycolysis, glycogenesis, and lipogenesis are the main functions of liver tissue. Many factors and proteins play a role in these processes, and two factors have recently been identified called E2F1 and E2F4.

The present study was approved by the ethics committee of Payame Noor University with the code IR.PNU.REC.1398.059. In terms of purpose, it is fundamental-applied, which was implemented experimentally. In the present study, 32 8-week-old male Wistar rats with an average weight of 237 ±33 g were purchased from the Pasteur Institute. After being transferred to the animal laboratory environment, these animals are housed in transparent polycarbonate cages in an environment with a temperature of 22 ± 1.4 °C, the humidity of 45 to 55%, four heads in each cage with free access to water and closed. Foods were maintained according to a 12-hour sleep-wake cycle. Animals were randomly divided into 5 groups: control group (Co) (8 heads), moderate intensity training (MIT) (8 heads), high-intensity training (HIT) (8 heads), and high-intensity interval training (HIIT) (8 heads) were divided.
The MIT protocol was performed in such a way that in the first week, 5 minutes of warm-up, 5 minutes of cooling, and 20 minutes of the main body of the exercise, including running at 65% VO2max at a speed of 20 m/min, was added to the training time every week. In the sixth week, the training time reached 37 minutes and remained constant until the end of the eighth. Also, the training speed was unchanged from the first week to the eighth week and was equal to 20 meters per minute.
The HIT protocol in the first week included: 5 minutes of warm-up, 5 minutes of cooling, and 20 minutes of running training with 65% VO2max at a speed of 20 m/min and an increasing slope of the treadmill. The training time was increased every week, so that in the sixth week the training time reached 30 minutes and remained constant until the end of the eighth. On the other hand, the slope of the strip was 2% in the first and second weeks and 2% was added to the slope every 2 weeks to reach 8% in the seventh and eighth weeks. Also, the training speed from the first week to the eighth week was 20 meters per minute and was kept constant. The HIIT protocol also included 10 minutes of warm-up before the workout, in the first to fourth weeks including 3 intense intermittent runs with an intensity of 90 to 100% VO2max and a speed of 30 meters per minute in 4 minutes and 3 low-intensity intermittent runs. With 50 to 60% VO2max and at a speed of 20 meters per minute in 3 minutes. From the fifth to the eighth week, it also includes 4 intense intermittent runs with an intensity of 90 to 100% VO2max at a speed of 30 meters per minute in 4 minutes and 3 low-intensity intermittent runs with 50 to 60% VO2max at a speed of 20 meters per minute. It took 3 minutes. The main body time of the exercise was 28 minutes per repetition. Mice in the control group did not participate in any exercise program but were placed on a stationary treadmill for 10 to 15 minutes per session to adapt to the environment to create the same conditions. After in vitro analysis of the samples, descriptive statistics including standard mean and standard deviation and inferential statistics were used to quantitatively describe the data. First, the Shapirovilk test was used to determine the normality of data distribution, and the Leven test was used to determine the homogeneity of variance. Due to the normal distribution of data, parametric tests including one-way analysis of variance and Tukey's post hoc test were used at a significance level of p≥0.05.

The results showed that there was a significant difference in the expression of the E2F1 gene in the liver tissue of male Wistar rats between the HIT group compared to the control group. There was also a significant difference between MIT and control groups (P = 0.003). Comparison between groups with post hoc test showed that there was no significant difference between HIT groups and MIT, HIIT, and control groups (P = 0.977, P = 0.917, P = 0.093, respectively). Post hoc tests in training groups showed that there was no significant difference in E2F4 gene expression between MIT and HIT, HIIT, and control groups (P = 0.977, P = 0.721, P = 0.202, respectively). On the other hand, a significant difference was observed between the HIIT group and the control group (P = 0.022, respectively).

In general, the results showed that there was no significant difference between IT MIT, HIT, and HIIT methods on E2F1 and E2F4 gene expression in liver tissue of male Wistar rats. However, there is a significant difference between training groups with control of differences.

The expression of adhesion molecule such as the intercellular adhesion molecule- I (ICAM-I) and vascular adhesion molecule- I (VCAM-I) in obese people may increase atherosclerosis phenomena and cardiovascular diseases. The purpose of the current study was to investigate the effects of 10-week high-intensity and moderate-intensity aerobic trainings on plasma levels of ICAM-I and VCAM-I in obese boys.

The statistical population of the present study was obese boys of Baharestan city. The sample included 36 obese student boys aged 13.4±0.69 years old, height: 163.06±7.88 cm; weight; 85.72±8.42 kg) who were randomly assigned to three groups: high-intensity training (n=‌12), moderate-intensity training (n=‌12), and control (n=12). The training was performed at 50%-65% maximal heart rate (moderate-intensity training group) and 70%-85% maximal heart rate (high-intensity training group), three days per week for 10 weeks. The blood sample was collected 48 h before and 48 h after the last session of exercise training. The ICAM-I and VCAM-I were measured via ELISA. Data were analyzed using two-way repeated ANOVA in SPPS, version 18.

The results indicated that body weight and BMI decreased significantly after moderate- and high-intensity training (p < 0.05). VO2max value significantly increased following 10 weeks of exercise training in both groups. No significant different was observed between exercise groups for plasma levels of ICAM-I. Moreover, the plasma levels of VCAM-I decreased significantly in the high-intensity training compared to the moderate-intensity training and control groups (p < 0.05).

It seems that intensity of training may decrease plasma levels of ICAM-I and VCAM-I through decrease of body weight and BMI and increase of VO2max.

 This study aimed to investigate a period of exercise activity with different intensities on decorin gene expression through interaction with transforming growth factor-beta (TGF-β) in male adult rats.

 This experimental study included 24 males adult Wistar rats that were divided into three groups (8 animals per group) of High-Intensity Training (HIT), Low-Intensity Training (LIT), and Control. Training groups trained for eight weeks and five days a week. The HIT group exercise program consisted of one hour of exercise for five 8-min intervals at 85%-90% Vo2max that were separated by 2-min intervals with an intensity of 50%-60% Vo2max. On the other hand, the LIT group exercise program included five 8-min intervals with an intensity of 55%-60% Vo2max, and 2-min intervals with an intensity of 45%-50% Vo2max. It should be noted that the control group received no exercise program.

 The results of this study showed that the expression levels of the decorin gene in the HIT training group were significantly higher than those in the control group (P=0.001), whereas the levels of decorin in the LIT training groups were not significantly different from those in the control group (P=0.11). The expression levels of the TGF-β gene in both training intensities (high- and low-intensity training, respectively) showed a significant difference, compared to the control group (P=0.001, P=0.18).

 According to the results of the present study, it seems that HIT exercise can lead to a greater increase in muscle growth due to increased TGF-β-dependent myokine, compared to LIT exercise.

 Exercise is one of the methods affecting cardiovascular adaptation, but its cellular and molecular pathways and mechanisms are unknown. T-Box Transcription Factor 5 (TBX5) gene seems to be one of the factors involved in regulating cardiac hypertrophy.

 The aim of this study was to investigate the effect of an 8-week exercise program with different intensities on the expression of TBX5 gene in the heart of male Wistar rats.

 In this experimental study, 24 male adult Wistar rats were divided into three groups of High Intensity Training (HIT), Low Intensity Training and (LIT) and control. Training groups performed the exercise program for 8 weeks, 5 sessions per week. The exercise program for the HIT group consists of running on a treadmill with five 8-min intervals at 85-90% VO2 max intensity divided into 2-min intervals at 50-60% VO2 max intensity, while for the LIT group it was included five 8-min intervals with 50-60% VO2 max intensity divided into 2-min intervals with 45% -50% VO2 max intensity. The control group performed no exercise. The real-time Polymerase Chain Reaction (PCR) analysis was used to measure the expression level of TBX5 gene. The collected data were analyzed by one-way ANOVA and Tukey’s post hoc test.

 The heart weight (P≤0.001 and P=0.004), heart-weight to body-weight ratio (P≤0.0001 and P=0.001), and left ventricular wall thickness were significantly higher in the HIT and LIT groups than in the control group (P≤0.0001 and P=0.38 ). The left ventricular wall thickness in the HIT group was significantly higher than in the LIT group (P=0.001). The TBX5 expression in the two training groups were not significantly different from that of control group (P=0.11).

 It seems that more intensive exercise can have more significant effects on cardiac hypertrophy than less intensive exercise.

Aging is accompanied by anatomical and physiological changes in most tissues and organs, especially the reduction of cells, tissues, and vascular levels. Endothelial progenitor cells are involved in maintaining endothelial health, preventing endothelial dysfunction, and increasing neovascularization process. Cardiac stem cells are effective in the regeneration and repair of heart tissue. Regular exercise training increases both of these cells. We aimed to investigate the effect of eight weeks of moderate and intense interval training on gene expression of endothelial progenitor cells and cardiac stem cells in aged rats.

Twenty-one Wistar female rats with the mean age of 24±1 months and the mean weight of 265±44 g were randomly divided into three groups of control (n=7), moderate exercise (n=7), and intense exercise (n=7) groups. Both exercise groups were trained for 8 weeks, 3 sessions a week, each session for 40 minutes with 28 meters per minute in the moderate intensity exercise group and 34 meters per minute in the high intensity group. Forty-eight hours after the last training session, the rats were anesthetized and their cardiac tissue was isolated. CD34 and KDR gene expression for endothelial progenitor cells and c-Kit expression for cardiac stem cells were measured.



Findings: The results showed that the level of c-Kit gene expression in both groups of moderate (P=0.0001) and intense (P=0.0001) training significantly increased compared to the control group. This increase was significantly higher in the intense training group (P=0.0001). Eight weeks of moderate interval training significantly increased the expression level of CD34 (P=0.0001) and KDR (P=0.0001) genes. Also, eight weeks of high intensity interval training resulted in a significant increase in the level of gene expression of CD34 (P=0.0001) and KDR (P=0.0001). This accumulative effect in the intense training group was significantly higher compared to the moderate group (CD34: P=0.0001 and KDR: P=0.0001).

The results of this study showed that regular interval training with two different intensity levels raises the level of gene expression of endothelial progenitor cells and cardiac stem cells. This increase is dependent on the intensity of training. High intensity interval training seems to stimulate the regeneration of heart tissue and development of coronary artery. These findings can be used to improve cell therapy and cardiac rehabilitation after injury and myocardial dysfunction, especially in the elderly.