ebrahim zarrinkalam

Cardiovascular and sports experts recommend the use of oxygen consumption cost indicators, heart rate and fatigue index to control work pressure in sports and rehabilitation. Meanwhile, it is very common to control the intensity of exercise by heart rate index. However, the maximum heart rate (HRmax) must first be measured or estimated as the basis for the calculations. The purpose of the present study is to evaluate the validity of HRmax estimation equations in healthy children.

The HRmax was measured and estimated in 205 healthy boys between 8 and 12 years old by two methods, Bruce's incremental exercise test and special equations for children. In order to compare the estimated and measured HRmax, Pearson's correlation, t-correlated and root mean square error (RMSE) were used.

A weak correlation between estimated and measured HRmax was observed (R=0.09-0.18). A significant difference was observed between the estimated and measured HRmax (beats per minute = 1.4-4.8) (P<0.05). So, the Nikolaidis equation led to a significant overestimation and the Shargal and Gelbert equations led to a significant underestimation of the HRmax. Also, the root mean square error values for HRmax estimation equations were high (RMSE = 6.9 - 7.4 beats per minute).

Considering the ineffectiveness of foreign equations for estimating the HRmax in Iranian children, it is recommended to design native equations for estimating the HRmax for Iranian children.

Background and Caffeine is a widely used and available physiological stimulant that is effective in sports performance. The purpose of this study was to investigate the effect of caffeine consumption and exercise on fatigue and cardiovascular responses in active men. The statistical population of this research was made up of all male students of physical education in the age range of 19 to 27 years with at least three activity sessions per week. 15 of them were selected as subjects and they performed the exercise protocol in two stages (the first stage by eating placebo and the second stage by eating coffee). Subjects consumed 5 mg/kg of coffee in the first session under placebo conditions, and in the second session, subjects consumed 5 mg/kg of coffee one hour before the test. Blood samples were collected before taking placebo or caffeine and after the test. The results of the correlated t-test showed that the consumption of caffeine supplements significantly increased the time to reach fatigue and the index of oxygen consumption after exercise. In general, it can be said that active men can use 6 mg/kg of caffeine supplement one hour before sports activity to improve the time to reach fatigue.

How to descend from a height is one of the most important questions that occupy the minds of climbers. In this study, we compared downhill running in two continuous and interval manner on delayed onset muscle soreness (DOMS), muscle damage and immune system indices in adolescent boys.

For this purpose, 20 healthy sedentary adolescent boys (16.4±1.03 years and BMI=20.06±2.6 kg/m2) distributed in two identical (anthropometrics and functional) groups and rapidly ascended to 3,000 m altitude by gondola, then  going downhill for a distance of 14 km in two continuous and interval styles. Immunological indices, hemoglobin, hematocrit, muscle injury (Lactate dehydrogenase and Creatine kinase) and DOMS were evaluated before, immediately, 24 and 48 hours later. Repeated measure ANOVA was used to statistical analyses. Significance level was set to less than 0.05

Immunological indices were not different between groups, but, the immune cells at 24 hours after activity decreased compared to pretest in continuous group. Creatine kinase and lactate dehydrogenase were not different between groups. These enzymes increased immediately after downhill running in both groups, but magnitude of changes in creatine kinase was more in continuous group. Also, DOMS in the continuous group was more than interval group.

The results showed that although the levels of the immune system indices and muscle damage were similar between groups, but, downhill running in a continuous style compared to the interval style causes suppression of the immune system and DOMS elevation in sedentary adolescent boys.

A high-fat diet causes hyperinsulinemia and increases insulin resistance in the body. On the other hand, the oxidative stress caused by hyperglycemia can lead to the exacerbation of hyperglycemia and increase the complications of diabetes, and cardiovascular diseases are one of the most important complications of diabetes mellitus. Therefore, the aim of this study was to investigate the effect of 4 weeks of aerobic training on catalase enzyme activity in the left ventricle and insulin resistance index in male rats treated with streptozotocin and exposed to a high-fat diet.

In this experimental study, 19 male wistar rats, with an average age of 8-12 weeks and a weight of 200-250 grams, were divided into 3 groups: diabetic control (CD 8), training diabetes (TD 8) and healthy control (C 3). The exercise program included 4 weeks of aerobic exercise with an average of 60 to 75 Vo2max in an increasing manner. Before and 48 hours after the last training session, blood was taken and left ventricular tissue samples were extracted to check the HOMA-IR index and catalase activity by ELISA method. To compare the study groups, one-way analysis of variance and Scheffe's post hoc test were used in SPSS software (p≥0.05).

The results showed that the induction of diabetes with STZ along with a high-fat diet causes a significant decrease in catalase enzyme (P=0.001) and a significant increase in HOMA-IR index, fasting glucose and Li index (P=0.001) in rats. However, doing 4 weeks of aerobic training caused a significant increase in catalase enzyme activity (P=0.001) and a decrease in HOMA-IR index, glucose and Li index (P=0.001).

Aerobic exercise with moderate intensity can be used as an effective non-pharmacological method in the treatment of diabetic cardiomyopathy by increasing catalase activity and reducing resistance to insulitis in diabetes.

High-intensity interval training (HIIT) is an effective training method for improving the aerobic and anaerobic power of athletes; however, the role of activity volume in high-intensity interval training efficiency is still unclear. Therefore, in the present study, the effects of low- and high-volume HIIT on aerobic power, anaerobic power, and lactate response in young soccer players were compared. In this study, 24 professional soccer players aged 20 to 22 who had no history of illness or taking supplements were chosen and randomly assigned to two groups of high-volume and low-volume HIIT. High-intensity interval training was completed for eight weeks. Training sessions included 5 min of warm-up, the main training phase, and cooling down. The training phase in the first week included 8 repetitions of 15 s of running with maximum power and 15 s of rest. Every week, the number of repetitions was increased by two. High-volume interval training was conducted for six sessions per week while low-volume interval training was performed for three sessions per week. After the training intervention, aerobic power was measured using the one-mile running test, and anaerobic power was evaluated using the Running-Based Anaerobic Sprint Test (RAST). Moreover, the level of blood lactate resulting from the RAST test was also measured using a lactometer. To statistical analyses repeated measure ANOVA was used. Blood lactate levels were reduced by 12% (p=0.001) in the high-volume interval group and by 10% (p=0.001) in the low-volume interval group in response to exercise. In addition, statistical analysis revealed that the blood lactate levels in response to exercise after 8 weeks of training were similar in both groups. On the other hand, despite the rise in aerobic and anaerobic power in both groups, there was no significant difference in aerobic and anaerobic power between the high-volume and low-volume groups after eight weeks of interval training. Overall, the findings of the present research indicated that high-intensity interval training will reduce lactate and increase aerobic and anaerobic capacity, regardless of the training volume.

Exercise training has been suggested as a potential non-pharmacological strategy to prevent cardiovascular injuries. However, the role of exercise is controversial in preventing the progression of injuries caused by diabetic cardiomyopathy or their repairing. Therefore, this study aimed to evaluate the effect of aerobic exercise training on left ventricular apoptotic and antioxidant indices in a high-fat diet and streptozotocin-induced type 2 diabetic rat model.

  Twenty-four male Wistar rats, 7-8 weeks of age, were randomly divided into two groups of normal diet (n = 8, ND) and high-fat diet (n = 16, HFD). The high-fat diet rats were given a free diet containing 55% fat for four weeks. For diabetes induction, 30 mg/kg of streptozotocin (STZ) was injected intraperitoneally into obese rats. Diabetic rats were subdivided into two groups: control diabetic (n= 8, CD) and diabetic-training (n = 8, TD) groups. The training group performed aerobic exercises on a treadmill for four weeks. The normal diet and control diabetic groups did not receive any exercise training.

Diabetes caused left ventricular catalase activity (p=0.001) reduction and increased caspase-9 (p=0.001) and P53 (p=0.001). Exercise training increased the maximum oxygen consumption rate by 37% (p=0.003) in the diabetic rats. The TD group had lower HOMA-IR (p=0.01) and plasma glucose (p=0.003) than the CD group. Also, aerobic training increased catalase (p=0.01) but decreased caspase-9 (p=0.001) and P53 (p=0.005) in the diabetic rats.

Progressive aerobic exercise training can contribute to insulin resistance amelioration by increasing catalase activity and reducing apoptotic indices. Therefore, aerobic exercise training can be used as an effective non-pharmacological method of treating diabetic cardiomyopathy.

Visual information acquired through observation plays a pivotal role in learning a movement pattern and motor control.

This study aimed to analyze the effect of visual deprivation on learning in rats.

The study sample consisted of 12 male rats, divided into three groups. Group I consisted of four rats and was considered the control group. Transection of the two optic nerves was performed on rats of group II on the seventh day after birth and group III on the seventh week after birth to develop the early blind and late blind models, respectively. A T-shaped maze device was utilized to evaluate the learning behavior of rats. Rats of groups II and III were blinded by the optic nerve surgery. In total, 20 trials per day were conducted for nine consecutive days, in which the time and number of correct arm entries were recorded. The ANOVA and Kruskal-Wallis tests were employed to analyze the results in SPSS software (version 16.0). A p-value of less than 0.05 was considered statistically significant.

There was a significant difference between the three groups regarding the number of correct arm entries on days one, three, and seven (P<0.05). There was also a significant difference between the three groups regarding how long it took them to enter the target box on days two and three (P<0.05). Group III had a lower number of entries to the target box and it took them a significantly longer time to enter the target box, compared to the other groups.

According to the results, visual deprivation may affect the learning of rats during the early days; however, their learning levels increased over the following days. Moreover, the early blinded rats had a higher level of learning than the lately blinded adult rats and the same level of learning as that of the sighted adult rats.

Exercise training cited as the most important non-pharmacological strategy to cardio-protective effects of preconditioning, but the molecular mechanism of this process is not yet clear. Therefore, in this study, we evaluated the cardio-protective effects of swimming training Preconditioning on Ischemia Reperfusion-Injury in male Wistar rats.

For this purpose, 20 male Wistar rats were randomly divided into control and training groups. The training group performed swimming training for 10 weeks (5 days per week, each session 60 min). All subjects underwent myocardial ischemia (30 min) reperfusion (120 min) surgery after intervention. Then, infarction size and oxidative stress indices were measured.

Statistical analyses showed that antioxidant indices GSH, GPx and Catalase induced-myocardial ischemia reperfusion were not different between groups, but MDA and MPO were significantly lower in the training group than in the control group. Also, infarction size area following ischemia reperfusion in the training group (34.32±6.4) was 8% less than the control group (42.17±9.7). 

The results of this study showed that ten weeks of swimming training reduced the size of the infarcted area after myocardial ischemia-reperfusion injury by reducing free radical production. These changes suggest protective preconditioning effects of swimming exercises.

The aim of this study was to evaluate the effects of resistance, endurance, and concurrent exercise on oxidative stress markers and histological changes of the intestine after morphine withdrawal in rats. A total of 30 male Wistar rats were randomly divided into 5 groups (n=6) including healthy control, withdrawal (rat received morphine for 21 days and 8 weeks of withdrawal period), withdrawal + endurance exercises, withdrawal + resistance exercises, and withdrawal + concurrent exercises. The rats practiced endurance, resistance, and concurrent exercises for 10 weeks. Then, their intestines were removed and used for biochemical and histological analysis. Next, several factors were measured such as total protein levels, malondialdehyde (MDA), reduced glutathione (GSH), total antioxidant capacity (TAC), and total oxidant status (TOS). Finally, the morphological alteration of intestine was examined under the light microscope. Morphine withdrawal significantly increased the levels of MDA in the intestine of withdrawal rats compared to those of the control group while endurance, resistance, and concurrent exercise reduced the MDA levels in the intestine. In addition, morphine withdrawal led to a decrease in TAC and GSH levels in the intestine compared to control rats whereas endurance, resistance, and concurrent exercise noticeably increased TAC and GSH levels. Interestingly, the change in the concurrent group was more significant. Moreover, the levels of TOS demonstrated a significant increase in the addicted rat as compared to the control group. Conversely, endurance, resistance, and concurrent exercise significantly decreased TOS levels and the reduction was more significant in the concurrent group. Finally, the intestine of withdrawal rat was morphologically abnormal while it restored by the exercise. Overall, endurance, resistance, and concurrent exercise significantly normalized oxidative stress and the morphological changes of the intestine in withdrawal rats.

Previous studies have shown that morphine dependence leads to myocardial dysfunction. In addition, apelin plays a protective role in cardiac function. The purpose of this study was to evaluate effects of morphine dependence and three models of exercise training on serum apelin level of dependent and healthy rats.

Ten healthy and 40 morphine-dependent rats were used in this study. The morphine-dependent rats were divided into four equal groups of control addicts, endurance training, strength training and concurrent training. The training exercises were carried out for eight weeks, five days a week. Serum apelin level was measured by ELISA, 72 hours after the last training session.

Statistical analysis demonstrated that apelin level increased significantly in morphine-dependent rats compared to healthy controls. On the other hand, endurance and concurrent training significantly increased serum apelin level in morphine-dependent rats compared to control addicts, but strength training had not effect on serum apelin level in morphine-dependent rats.

Endurance and concurrent training may have cardioprotective effects on morphine-dependent rats by increasing serum apelin levels. Therefore, such training activities could be recommended to morphine-dependent patients to prevent cardiac disorders.

Cerebral palsy is the most common chronic motor disability in children and can have negative effect on motor functions. The purpose of this study was to investigate the effect of eight weeks resistance training on gross motor ability, balance and walking speed in a group of such children.
21 cerebral palsy boys with spastic diplegia, aged between 12 and 16 years (mean, 13.66 years), participated in this study. A pre-test, involving walking, sitting, standing and walking up stairs. They were randomly divided into an experimental and control groups. Then, the experimental group participated in 8 weeks of resistance training. The data was attained from a 10 meter walk test, Berg Balance Test, gross motor ability Section E, D and GMFCS tests. Kolmogorov-Smirnov test, sample t-test were used for analyzing the data.
The results showed a significant improvement in the performance of experimental group in gross motor abilities section E and D, balance and walking speed after 8 weeks of resistance training (P The results showed that resistance training improves gross motor ability, balance and gait in children with cerebral palsy hence, it is recommended that resistance exercise be used as a therapeutic modality for children with cerebral palsy.

Apelin has recently been identified as an analgesic agent and a novel neuropeptide. On the other hand, it has been shown that exercise can lead to reduced pain in morphine-dependent patients..
Therefore, the aim of this study was to evaluate apelin and pain threshold changes in healthy and morphine-dependent rats in response to two exercise paradigms..
In this study, 30 healthy and 30 morphine-dependent rats were used. Morphine-dependent and healthy rats were divided into six groups: 1, a control (healthy) group; 2, a healthy endurance group; 3, a healthy strength-training group; 4, an addicted control group; 5, an addicted endurance group; 6, an addicted strength-training group. Then, the training groups performed aerobic and strength training for eight weeks. After the training program, the tail flick and formalin tests were used to assess pain. Apelin was also measured by ELISA..
Regardless of the type of exercise, exercise significantly increased the apelin serum levels in healthy rats. The apelin levels significantly increased in the morphine-dependent rats compared with the healthy control group. Endurance, unlike strength training, significantly increased apelin in the serum compared to the addicted control group. The training led to pain relief in the morphine-dependent rats and returned it to the healthy control group level. The Pearson correlation showed a reverse significant correlation between the serum apelin level and the tail flick test in the morphine-dependent rats..
The results showed that endurance training reduced pain by increasing apelin in morphine-dependent rats. Therefore, it is suggested that this type of training be considered for the morphine-dependent patients for pain relief..

Many evidence showed that exercise training has beneficial effects on skin blood flow in the health and diabetic condition. On the other hand some finding showed that C-peptide has protective and therapeutic effect on vascular dysfunction-induced by diabetes. Therefore the purpose of this study is effects of resistance exercise on vascular function of C-peptide. In this experimental study، Male wistar rats (220±10g، N=30) were used in two diabetic (control and trained) and one age-matched healthy control groups. After 1 week of diabetes induction، animals were submitted to resistance exercise training for 9 Weeks on ladder. To characterize cutaneous micro vascular responses by Laser Doppler flowmetery، animals were deeply anesthetized by intraperitoneal injection of pentobarbital sodium (50 mg/kg). For data analysis، one-way ANOVA test was used to compare the groups. Statistically significant difference between the minimum acceptable levels is p<0. 05 Local microinjection of c-peptide increased coetaneous blood flow in trained and control diabetic rats، however this effect in trained group is higher than control diabetic group rats. Administration of Nw-nitro-L-arginine (nitric oxide synthase inhibitor) before C-peptide reduced significantly C-peptide vascular effects in trained and control diabetic rats. Chronic resistance exercise potentiate C-peptide vascular function، possibly by nitric oxide pathway