نشریه فیزیولوژی ورزش و فعالیت بدنی
سال شانزدهم شماره 3 (پاییز 1402)

Aging is a complex physiological process that involves progressive loss of body function and degradation of DNA strands located at the ends of chromosomes-telomeres. The capacity of cells to divide is limited by telomere length, as an excessive shortening of telomeres causes cellular senescence. Exercise training and omega-3 prevent the shortening of telomeres by affecting telomerase. The aim of the present study was to investigate the effect of aerobic training with omega-3 on some shelterins and telomerase of heart tissue in elderly high-fat diet rats.

In this experimental study, 40 male Wistar rats (mean weight 311.32±26.95 g) were obtained from the Pasteur Institute and transferred to the laboratory. After transferring the rats to the laboratory, they were randomly divided into five groups: Normal Diet (ND), High-Fat Diet (HFD), High-Fat Diet-Training (HFDT), High-Fat Diet-Omega3 (HFDω3), and High-Fat Diet-Training-Omega3 (HFDTω3). HFD induction was performed using a high-fat diet containing 17% protein, 43% carbohydrate, and 40% fat. The supplement groups received 1 g of Omega3 (per kg of body weight) orally during the intervention period. The aerobic exercise program at the beginning consisted of running on a treadmill at a speed of 10 m/min, 0-degree incline, for 15 minutes. The speed and duration gradually increased to 16 meters per minute and 50 minutes in the last session. Running was carried out for 8 weeks and five days a week. Data were analyzed by one-way analysis of variance and Tukey post hoc test at the P < 0.05.

Induction of HFD significantly decreased the expression of TRF2 (P = 0.002), TERT (P = 0.024) and increased TRF1 (P = 0.0001) compared to the ND group. Exercise and omega-3 significantly increased the expression of TRF2 and TERT in HFD rats (P < 0.05). Also, TRF2 and TERT expression changes were higher in the HFDTω3 group compared to HFDT (P = 0.023 and P = 0.044, respectively) and HFDω3 groups (P = 0.021 and P = 0.042, respectively).

The results of the present study showed that elderly and HFD are associated with a decrease in TRF2, TERT and an increase in TRF1 in heart tissue, and aerobic exercise and omega-3 consumption can reverse this trend. Considering the role of shelterins and telomerase in cellular function, it seems that changing the levels of these indicators following physical activity and using omega-3 supplements can partially prevent the occurrence of many heart diseases caused by aging and obesity.

The expansion of fat tissue depends on its angiogenesis rate, and exercise activities affect various angiogenic factors in this tissue. With the expansion of fat tissue and adipogenesis, a dense and closed capillary network is formed in this tissue, which can suppress angiogenic factors. If there is a wide capillary network and angiogenic factors such as VEGF-A in this tissue, the expansion of fat tissue can be prevented. The aim of this study was to investigate and compare the effect of a variety of endurance exercises on the expression of angiogenic genes vascular endothelial growth factor (VEGF-A) and thrombospondin-1 (TSP-1) in the subcutaneous fat tissue of rats.

In this experimental study, 32 male Wistar rats aged eight weeks and weighing 237 ± 33 grams were randomly divided into four equal groups of control, high-intensity progressive continuous aerobic training (HIT), moderate-intensity continuous aerobic training (MIT) and, high-intensity interval aerobic training (HIIT). The treadmill training protocols consisted of eight weeks, so that the HIT training consisted of running at a speed of 20 m/min or at an intensity of 65% of the maximum oxygen consumption (VO2max), with a gradually increasing slope for 30 minutes. MIT training consisted of running with an intensity of 65% VO2max for 37 minutes, and HIIT training consisted of four high-intensity intervals with four minutes of running with an intensity of 90-100% VO2max and four low-intensity intervals with a duration of three minutes with 50-60% VO2max (28 minutes in total). Finally, 48 hours after the last training session, the subcutaneous fat tissue was isolated and the expression of VEGF-A and TSP-1 genes in the subcutaneous fat tissue was measured by RT-qPCR method. The resulting data were analyzed using a one-way analysis of variance and Tukey's post hoc test, and the significance level was considered P ≤ 0.05.

The findings of the present study showed that all three exercise interventions significantly increased the expression of the VEGF-A gene in subcutaneous fat tissue; But only HIT training could significantly reduce the expression of TSP-1 in this tissue (P ˂ 0.05). Also, the increase in VEGF-A expression was significantly higher after HIT training compared to HIIT (P ˂ 0.05).

According to the findings of this study, high-intensity and progressive continuous aerobic training is probably the most desirable training method to increase angiogenesis in subcutaneous fat tissue. These types of exercises can be effective in reducing fat mass by improving blood supply to fat tissue.

increased oxidative stress is the main characteristic of all types of age-related injuries. Regarding the role of physical activity in adaptive responses to oxidative stress and importance of nutritional supplements, the aim of this study was to investigate the effect of six weeks of high-Intensity interval training along with the consumption of  coenzyme  Q10 supplements on the values of Nrf2, NQO1  in the soleus muscle of elderly rats.                                                                                                                                   

The current research was an experimental and fundamental type, which was conducted in the animal laboratory of Shiraz University. Forty-four elderly male Wistar field rats were used to carry out the research. After a one-week familiarization with the training environment, the animals were randomly divided into high-intensity interval training groups, a supplemental group, high-intensity interval training group with supplementation, and a control group (11 in each group). Subjects in the training groups performed interval high-intensity training for six weeks. So that in the first week, three interval repetitions were performed, in the second week, 5 interval repetitions, in the third week, 7 interval repetitions, and from the beginning of the fourth week to the end of the sixth week, nine interval repetitions were performed. Subjects in the supplement groups also consumed 200 mg of supplement per kilogram of body weight daily. After completing the training and supplementation period, the animals were anesthetized by injecting ketamine and xylazine, their soleus muscle was removed by open surgery, and after being transferred to a nitrogen tank, they were kept in a -80 freezer for western blotting. In order to answer the research questions, a one-way analysis of variance was used, and Tukey's post hoc test was used to check the differences.     

The findings of the research showed that high-intensity interval training along with Q10 supplementation has no significant effect on the Nrf2 values of the soleus muscle of elderly rats (P > 0.05). However, high-intensity interval training with and without coenzyme Q10 supplementation, as well as coenzyme Q10 supplementation, only significantly decreased the NQO1 values of the soleus muscle of aged rats (P < 0.001).

Considering the lack of effect of high-intensity interval training on Nrf2 and NQO1 reduction in elderly rats, in order to determine the mechanism of the effect of high-intensity interval training on antioxidant pathways, the conditions of the exercise program such as duration, intensity, repetition and exercise sets should be taken into consideration; It is also recommended to consider other standard dosages of coenzyme Q10 supplementation.

Resistance exercise with new training methods such as blood flow restriction, which is performed with lower intensities than the traditional method, can lead to different physiological responses. The purpose of this study was to investigate the effect of a period of upper body resistance exercise with blood flow restriction on the level of cortisol, testosterone and the ratio of testosterone to cortisol in male judo players.

Thirty male judo players were divided into two groups of resistance training with and without blood flow restriction. The training program consisted of 6 weeks of resistance training, 3 sessions per week. Resistance exercise with blood flow restriction included performing barbell biceps curl exercise at an intensity corresponding to 30% of one repetition maximum (1-RM) with cuff pressure about 120 to 160 mm Hg (around the proximal area of the arm) based on the systolic pressure of each person. For the traditional resistance training group (without vascular occlusion), subjects performed biceps exercise at an intensity corresponding to 75% of 1-RM.  To measure testosterone and cortisol, first blood sample (5ml) was taken before training from the antecubital vein of the right hand. The second blood was taken 48 hours after the last training session of 6th week, the third blood sample was taken 24 hours before the start of the second 6-week activity and the fourth sample was taken 48 hours after the last training session (after 12 weeks).

Between-group comparisons showed that cortisol (P=0.018), testosterone (P<0.001) and the ratio of testosterone to cortisol (P=0.001) were significantly different beuween two groups of resistance training with blood flow restriction and resistance training. Within-group comparisons showed that cortisol (P<0.001; d=1.76), testosterone (P<0.001; d=4.03) and the ratio of testosterone to cortisol (P<0.001; d=1.53) were increased significantly following resistance training with blood flow restriction and the percentage of changes were 38.48, 121.11 and 53.57%, respectively. Moreover, cortisol (P<0.001; d=1.27), testosterone (P<0.001; d=2.05) and the ratio of testosterone to cortisol (P=0.010; d=0.63) increased significantly in resistance training group by 25.35, 60.29 and 21.66 %, respectively.

According to the results of the research, it could be concluded that both traditional resistance training and resistance training with blood flow restriction can lead to increases in testosterone, cortisol and the ratio of testosterone to cortisol. Furthermore, according to the size of the effect and percentage of differences, it can be mention that effectiveness of resistance training along with blood flow restriction is more pronounced than traditional resistance training.

The effect of plyometric training on physical function is well known and the effect of exercise training with blood flow restriction has also been studied. However, the effect of aquatic plyometric with blood flow restriction has not been studied. Therefore, the aim of this study was to investigate the effect of aquatic plyometric training with and without blood flow restriction on physical fitness in young active women.

The study was a quasi-experimental study with a pre-post test. Thirty young women aged 18 to 30 years were randomly allocated to three groups: aquatic plyometric training with blood flow restriction (n = 10), aquatic plyometric training without blood flow restriction (n = 10) and control (n = 10). The protocol included six weeks of plyometric training (three days a week). The intensity of training (number of sets and repetitions) was considered less in the group with blood flow restriction than the other group. Restriction of blood flow was applied by tightening the elastic band of the upper thigh. Physical function tests were taken before and after the training program. Data were analyzed by using repeated measures of ANOVA with between subject factor. The significant level was set at P≤0.05.

Significant improvements were found in fat percentage, anaerobic power, lower body power, speed and maximum strength following aquatic plyometric training with blood flow restriction (P<0.05). There were no significant differences between the groups in other variables of physical function including weight, body mass index, agility and upper body power (P>0.05).

According to the results of this study, aquatic plyometric training with blood flow restriction could be effective in improving fat percentage, anaerobic power, lower body power, speed and maximum strength of young active women.

Bile acids are known as key metabolic messengers during liver regeneration and the end product of cholesterol catabolism, which are important for nutrient absorption in the intestine. Recent studies describe bile acids as messenger molecules with diverse functions that have a wide range of receptors in the body. Due to these receptors, bile acids can modulate the rate of self-synthesis, lipid, and glucose and energy metabolism. The FXR-FGFR4-KLB signaling pathway and its role in the regulation of bile acid biosynthesis is one of the novel issues in cholesterol metabolism, especially in the condition of non-alcoholic fatty liver disease (NAFLD). Despite the recommendations for patients with NAFLD to participate in regular exercise, the type, intensity and duration of exercise that is most beneficial for these patients is not clearly determined yet. Resistance exercise can be effective in improving NAFLD conditions by increasing fat oxidation, controlling appetite and reducing energy intake. This research was carried out to study the effect of eight weeks of resistance training on liver bile acid (BA), beta klotho protein (KLB) and the expression of farnesoid X receptor (FXR), fibroblast growth factor 15 (FGF15) and fibroblast growth factor receptor 4 (FGFR4) in male rats with non-alcoholic fatty liver disease.

In this study, 16 male Wistar rats (age, six-weeks and weight, 120-160 gr) after induction of NAFLD conditions, with six weeks of high-fat diet were randomly divided into two equal groups (n=8 in each group) of Control (C), and resistance training (R). The resistance training protocol included climbing on a 1-meter ladder with a 2-cm grid and an 85-degree incline. Weighted cylinders ranging from 50 to 75% of their body weight were attached to the rats' tails. The training was carried out for eight weeks period with a frequency of five days per week. Rats were sacrificed 48 hours after the last training session, and the liver tissue samples were taken to for measuring the variables. Data were analyzed by using independent t-test at a significance level of p<0.05.

Following eight weeks of resistance training, hepatic BA decreased significantly in R group compared to C group (p=0.001). In addition, KLB protein levels (p=0.001) and the expression of FXR (p=0.001), FGF15 (p=0.001), and FGFR4 (p=0.001) genes were significantly higher in R group compared to C group.

Non-alcoholic fatty liver is associated with a decrease in the expression of genes such as FXR, FGF15 and FGFR4, as well as a decrease in klotho protein, which results in a disturbance in cholesterol status and subsequent cell damage in the liver. The exercise intervention may have positive effect on the signaling pathway of FXR-FGFR4-KLB and its role in regulating the biosynthesis of bile acids and improve cholesterol metabolism in the body. It seems that resistance training has beneficial effects in improving this signaling pathway.The data of the present study indicate a possible relationship between resistance training and improvement of fat metabolism in the liver. The muscle-liver axis and the role of this type of exercises on the up-regulation of genes involved in the biosynthesis of hepatic bile acid and then the control of cholesterol metabolism can help in achieving a better understanding of the pathogenesis of NAFLD.

Type 2 diabetes is one of the most common metabolic diseases known in the world and is the main cause of death in many countries, affecting many people every year. Chronic hyperglycemia caused by type 2 diabetes causes oxidative stress, therefore this study compared the effect of eight weeks of traditional resistance training and Total Body Resistance Exercise (TRX) on some oxidative and anti-oxidative indicators in women with type 2 diabetes.

Thirty women with type 2 diabetes (age, 40-55 years) participated in the study and randomly were divided into three groups of resistance training (n=10), TRX group (n=10), control group (n=10). The experimental groups performed traditional resistance training and TRX three times a week for eight weeks at an intensity corresponding to 80-65% of a maximum repetition, while the control group did not participate in any training program during this period. Blood samples were taken from all subjects before training and 48 hours after the last training session and were used to determine the serum level of superoxide dismutase (SOD), Glutathione Peroxidase (GPx) and malondialdehyde (MDA). Paired t-test was used to investigate the within-groups differences, and the analysis of covariance using Bonferroni's post-hoc test was used to investigate the differences between groups.

Present study showed that after eight weeks of traditional resistance training and TRX, significant increases in SOD and GPX levels were observed in the two experimental groups (p< 0.05). However, no significant difference was observed in the control group. MDA levels decreased in both traditional and TRX resistance training groups. The results of between-group analysis showed that there is no significant difference between the two groups of resistance training and TRX for SOD, GPX and MDA indices (P>0.05).

Based on said the findings of present study it could be concluded that both training methods can improve oxidative (SOD and GPX) and anti-oxidative (MDA) indices in women with type 2 diabetes.

Accurate measurement of cardiorespiratory fitness (VO2max) is very important in sport sciences. The direct measurement of VO2max using a respiratory gas analysis device cannot be very operational and comprehensive due to the high cost, time-consuming, need for an expert, and the possibility of some cardio-respiratory risks during the performance of an increasing exercise test. Estimating VO2max using equations based on heart rate index (HRindex) is one of the most widely used methods in sports fields, which can estimate an individual's VO2max without needing breath gas analysis. However, this requires accurate measurements of resting and maximal heart rates with the least error. In the present study we aimed to evaluate the validity of VO2max equations based on heart rate index in adolescent boys.

One hundred and fifty-seven healthy adolescent boys (Mean±SD; age, 14.92±1.35 years; BMI, 21.39 ± 4.50 kg/m2 and VO2max: 41.80 ± 6.67 ml/kg/min) from middle and high schools in Hamadan city voluntarily participated in this cross-sectional study. Initially, the resting heart rate and body composition of the subjects were measured. The subjects' VO2max and maximal heart rate were measured by the respiratory gas analysis method by using modified Bruce incremental exercise test (criterion method). Moreover, the subjects' VO2max were estimated using HRindex-based equations. Pearson correlation, pair sample t-test, and Bland and Altman agreement were used to evaluate the validity of heart rate index based on VO2max equations.

A significant correlation was observed between the criterion method of VO2max and HRindex-based VO2max equations (R=0.328, p<0.05). A significant difference (p<0.05) was observed between measured and HRindex-based VO2max equations (Mean difference = 3.34 - 5.45 ml/kg/min). In healthy adolescent boys, both estimation equations led to underestimation of VO2max by 11.36 ± 17.93% and 5.84 ± 16.39%, respectively. In addition, the Bland and Altman plot showed low agreement between measured and HRindex-based VO2max equations.

HRindex-based VO2max equations do not have sufficient validity to be used in healthy adolescent boys and they led to the underestimation of VO2max. Therefore, it is recommended to employ HRindex-based VO2max equations for healthy adolescent boys.

Vascular endothelial growth factor (VEGF) is the most important marker of angiogenesis that may increase in response to exercise. However, the effect of acute exercise on this marker has been reported inconsistently. Therefore, the aim of this systematic review and meta-analysis is to investigate the effect of acute exercise on circulating VEGF in adults.

In order to extract original articles, a comprehensive search was conducted in the databases of PubMed, Scopus, Web of Science, SID, Magiran and Google Scholar until 2023 March 1 for studies investigating the effects of acute exercise on circulating levels of VEGF. The meta-analysis criteria included studies published in Persian and English language journals, studies with human subjects with an average age of more than 18 years, studies investigating the effect of acute exercise, and studies measuring serum or plasma VEGF levels. To determine the effect size, standardized mean differences (SMD) values and 95% confidence intervals (CIs) were calculated using CMA2 software. The level of heterogeneity was assessed using the I2 test and the publication bias was also assessed with Egger's test.  Furthermore, subgroup analysis was performed for health status (with chronic disease and healthy) and type of exercise (aerobic, resistance and high-intensity interval exercise).

In total, 27 articles (49 exercise interventions) including 704 subjects were included in the meta-analysis. The results of data analysis showed that acute exercise did not lead to significant changes in VEGF immediately after exercise compared to baseline [0.17, (CI: -0.05 to 0.40, p=0.14). The results of subgroup analysis based on the health status showed that exercise had no significant effect on VEGF in healthy subjects [SMD: 0.10, p=0.40], while it tended to increase VEGF in patients [SMD: 0.30, p=0.05]. The results of the subgroup analysis based on the type of exercise also showed that resistance exercise [SMD: 0.58, p=0.008] leads to a significant increase and high-intensity interval exercise [SMD: 0.29, p=0.06] leads to a non-significant increase in VEGF, while the effect of aerobic exercise [SMD: 0.009, p=0.95] was not significant.

In general, the findings of this meta-analysis showed that the type of exercise plays an effective role in the responses of VEGF to acute exercise. Resistance and high intensity interval exercise may lead to an increase in circulating VEGF immediately post exercise, while aerobic exercise does not have significant effects. In addition, exercise may increase VEGF in people with metabolic-cardiovascular disease, whereas, it is not effective in healthy individuals.

There is a close relationship between liver mitochondrial dysfunction and the development of obesity and insulin resistance. As observed in type 2 diabetes, in conditions of insulin resistance, a decrease in insulin sensitivity of liver cells, skeletal muscle and fat cells is observed. In recent decades, physical activity has become a key tool in controlling many diseases, including type 2 diabetes, and studies have shown that various training protocols are effective in reducing the epidemic and improvement of some metabolic functions of the liver. The purpose of this study was to evaluate the effect of eight weeks of high intensity interval training (HIIT) on Parkin and Pink1 proteins in the liver tissue of type 2 diabetic rats.

In an experimental design, 30 three-month-old adult male Wistar rats with a weight range of 250-300 g were randomly divided into three groups of 10 including healthy control (C: intraperitoneal injection of saline), Diabetic control (D: diabetic with high-fat diet combined with intraperitoneal injection of streptozotocin) and trained diabetic (D+T: diabetic with exercise) were divided. The training protocol encompassed running at an intensity of 85%-90% of the maximum speed in 6 to 12 two-minute intervals; 5 days a week for eight weeks. Fourty eight hours after the last training session and after 12 to 14 hours of fasting, all rats were anesthetized and operated by a trained specialist without pain. A method based on Western blotting was used to determine changes in the expression profile of Parkin and Pink1 proteins in the heart muscle tissue (left ventricle) of rats. The two-way analysis of variance and Bonferroni’s post-hoc test were used to analyze the data.

Induction of diabetes (D) causes a 51% and 63% increase in Parkin and Pink1 proteins, respectively, although it is not statistically significant (P>0.05). In addition, exercise intervention caused a 45% and 38% decrease in Parkin and Pink1 in the trained diabetic group (D+T) compared to the diabetic group (D), but it was not significant (p≥0.05).

According to the results, it can be stated that eight weeks of HIIT is insufficient to observe a significant reduction of mitophagy in the liver tissue of diabetic rats. At the same time, based on the partial changes of the indices, HIIT might be a preventive measure against the abnormal increase of mitophagy as a result of type 2 diabetes. However, to making a definite conclusion about these indices and how they are affected by different conditions more researches are needed.