فهرست مطالب farzad nazem

Background and Purpose:

The maximal heart rate is a physiological index to control the intensity of physical activity in exercise and rehabilitation. Due to the practical problems of measuring maximal heart rate in strenuous exercise tests, this physiological index is estimated by regression equations. Most scientific sources have used the two equations of Fox (age - 220) and Tanka (208 -0.7 age) to estimate the maximal heart rate. Fox and Tanaka's equations were designed based on the data obtained from the adult population. Therefore, these two equations may not be highly accurate in the child and adolescent population. The purpose of this research is to evaluate the validity of Fox and Tanaka's equations in estimating the maximal heart rate of children and adolescent boys.

In the present study, maximal heart rate was measured in 349 healthy boys aged 8 to 18 years in a direct method by using modified Bruce test on a treadmill equipped with a respiratory gas analyzer. Thereafter, the maximal heart rate was estimated using Fox and Tanaka’s equations. In order to validate the equations of Fox and Tanaka, the measured and estimated maximal heart rate were compared in all subjects as well as children and adolescent. For this purpose, Pearson's correlation, pair sample t-test, and Bland-Altman's agreements were used.

With increasing the age of the subjects, there was no noticeable change in the maximal heart rate of the boys. So that, a weak negative correlation was observed between age and maximal heart rate (r = -0.198, p<0.05). A significant correlation was observed between the maximal heart rate measured by the standard method with Fox (r=0.198) and Tanaka (r=0.198) equations (P<0.05). However, there was a significant difference between the measured maximal heart rate and estimated maximal heart rate by Fox (mean difference = 5.23±6.32, equivalent to 2.7% of the mean for maximal heart rate) and Tanaka (mean difference = 3.07±6.17, equivalent to -1.44 percent of mean for measured maximal heart rate). The Fox and Tanaka equations led to overestimation and underestimation of maximal heart rate, respectively. Furthermore, the Bland-Altman diagram indicated a low agreement between the maximal heart rate equations of Fox and Tanaka compared to the standard method. Even by dividing the subjects into two age groups, 8 to 13 years and 14 to 18 years, no changes in the results were found. No significant correlation was observed between maximal heart rate of Fox and Tanaka equations with standard method (r = 0.028-0.094) (p<0.05). In addition, a significant (P<0.05) difference was observed between the standard maximal heart rate and the Fox and Tanaka equations (mean difference = - 3.55 to 6.26 beats per minute).

It seems that the Fox and Tanaka heart rate equations do not have sufficient validity in children and adolescent boys. However, in situations where we have to estimate the maximal heart rate, Tanaka's equation has a lower estimation error. According to the results of this research, it will be beneficial to design a native equation for estimating the maximal heart rate of Iranian children and adolescent boys.

Cardio-respiratory fitness (CRF) is a strong predictor of overall health and is considered a key physiological measure in health care settings. Maximal oxygen uptake (VO2max) is considered the gold standard for measuring CRF. Non-exercise VO2max regression equations provide a safe, simple and relatively accurate means of measuring CRF in the general population. This study aimed to develop first native regression equations to predict of CRF without exercise test in Iranian healthy boys.

Laboratory gold standard CRF and anthropometric variables were measured in 597 healthy boys (8-17 yr) in Hmadan City, Iran in 2019. Multiple regression analysis was used to generate CRF regression equations. Cross validation of the CRF regression equations was assessed using PRESS statistics, Pearson correlation, Bland-Althman plot and paired t-test

CRF regression equations based on age, body mass index, body fat and resting heart rate were developed (R2=0.602 – 0.639, SEE = 3.42 – 3.73 ml/kg/min). PRESS statistics show that, shrinkage of the R2 (0.04 – 0.06) and the increment of SEE (0.18 – 0.25 ml/kg/min) is minor. There was strong correlation (R =0.847–0.883, P<0.001) and no significant difference (min diff= 0.09–0.18 ml/kg/min, P>0.05) between measured and predicted CRF. The Bland-Altman plot illustrates the strong agreement between the two values.

We introduced simple and satisfactorily accurate CRF regression equations based in healthy boys. Prediction of CRF of the boys by regression equations would provide a simple tool for assessing cardiorespiratory fitness in large studies including Iranian boys.

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.

The purpose of this study was determine the effect of upper body plyometric training on anaerobic power and record of 25 meters front crawl performance in 10 years old swimmer boys. 16 swimmer boys chosen voluntarily (The mean age was 9.9 ± 0.7 years ، weight 45.9 ±9 kg , Height 149.8 ± 5 cm، BMI  is 19.20 ± 3 Kg / m 2 ) And Subjects divided into two groups of training (n=8) and control(n=8).Before and after the implementation of the protocol investigate test 25 meters front crawl performance  at the distance 10, 20 and 25  metrs  and the number of hand strocke to check the performance of the swimming also anaerobic hand wingiting test function was evaluated. To analyze data, used the covariance test.The results showed six weeks upper body plyometric training Performance Indicators an hands Front crawl Including Peak power increased Significantly (18%) but the average power increase (7%) was not significant (p>0.05). Also, Swimming performance at of 10 meters) 8% (,10 to 20)6%(and 25 meters distance(3/80%) growth in compare to control group that was significant(p <0.05) As well as in the number of hand strocke, Plyometric training group although had growth in swim 10 meters (11%), 10-20 meters (7.5%) and in 25 meters distance (5.33%) but the isnt significance (p>0.05). results indicate that six week upper body plyometric traning to an increase and improvement in the measured parameters, and can be used as a complementary training method in young swimmers.

Accurate and fast estimation of maximal oxygen uptake (VO2max) as an indicator of cardio-respiratory fitness (CRF) by regression equations without exercise tests in large populations is of great importance in the field of health and sport sciences. Therefore, the aim of this study was to evaluate the cross-validation of the non-native non-exercise (N-EX) regression equations in estimating VO2max of healthy and adolescent boys using the standard method of respiratory gas analysis.

This research was a cross-sectional study in which 349 healthy boys children and adolescents (age: 12.49±2.72 year, BMI: 20.13±4.70 kg/m2 and VO2max: 41.50±6.47 ml/kg/min) were participated. VO2max was measured on a treadmill by the respiratory gas analysis in modified Bruce exercise test (criterion method) and then estimated by three non-native N-EX regression equations. To evaluate the cross-validation the validity of the N-EX regression equations, Pearson correlation, paired sample t-test and Bland-Altman agreement were used for extraction of results.

A significant correlation was observed between VO2max measured by criterion method and N-EX equations (R=0.63 - 0.73, p<0.01). However, a significant difference (p<0.01) was observed between VO2max of criterion method and predicted VO2max by N-EX regression equations (mean difference=6.4–11.69 ml/ kg/min). Also, the Bland-Altman plot showed low agreement between measured and predicted VO2max.

The nonnative N-EX regression equations studied in the present research do not have the necessary accuracy to estimate the VO2max of in healthy children and adolescent boys. Therefore, it seems necessary to verify foreign N-EX VO2max regression equations before use in the Iranian population.

Dysfunction in the autonomic nervous system can cause cardiovascular complications in patients with type 1 diabetes (T1D). The present study aimed to investigate the effect of combined exercise training on heart rate variability (HRV-5min), aerobic capacity (VO2max), and glycemic index in boys with T1D.

In this semi-experimental research, 24 adolescent boys with insulin-dependent T1D and 12 healthy boys of the same age with an age range of 12 to 18 years were selected and divided into three groups: healthy, control diabetic, and exercise diabetic. The exercise diabetic group performed combined exercises for 12 weeks, three sessions a week. Blood variables and cardiac variables were measured 48 h before and 72 h after the intervention. Dependent t-tests and one-way analysis of variance were used for statistical analysis.

After the intervention, a significant increase in VO2max variables, high frequency HRV (HF) and a significant decrease in Resting Heart Rate Variables (HRrest), the ratio of low frequency to high frequency HRV (LF.HF) and glycemic index were observed in the exercise diabetic group (P<0.05). In addition, in the inter-group analysis of the difference between the pre-test and post-test results, a significant difference was observed in VO2max, HRrest, HF, LF.HF, and blood glucose indices in the exercise diabetic group compared to the healthy and diabetic control groups (P<0.05).

Our results showed that combined exercise training along with insulin-dependent treatment could help to strengthen the cardiovascular system (HRV) in boys with T1D by improving the function of the parasympathetic branch of the autonomic nervous system.

Scientific evidences indicated that occurance of the imbalance during walking and gait disfunction profile could be related to a multiple sclerosis conditions . Otherwise , exercise activities as a non- pharmacological agent could be effectiveness for MS persons . Aim of this study, is Pilates and TRX programs intermediate on the dynamic balance , functional capacities in females with a multiple sclerosis conditions

in this study 30 females with a MS conditions ( mean age : 57/7 ±41/37years ,disease history : 77/3 ± 31/11 ys and disability grade : EDSS 84/0± 81/1 ) were randomly divided into three groups of 10 people. control group, TRX and Pilates groups activated for a 8 weeks periods with a 3 days interval weekly . Dynamic balance, functional capacities variables were measured by a standard styles. Statistical analysis of data performed with a ANCOVA – ONE Way . A p value of 0.05 was set.

TRX and Pilates programs were induces a significantly differentces in Berg balance ,walking timing period ,TUG test , and 6 min speed walking (6MWDT ) in the two training groups and more prominently in the TRX group comparison with a control group ( p<0.05). But 2MWDT parameter in 3 groups weren,t outstanding statistically

Findindg indicated that TRX and Pilates programs intermediates were caused an improvement in functional capacities and balance indexes in females with a MS conditions. However, it seems that TRX pattern role on the selected independents variables was obviousely than a Pilates pattern

Obesity and a sedentary lifestyle factors related to pulmonary function andcardiorespiratory requirements (CRF). This study was to determine the effect of regular aerobic trainingon cardiac and respiratory function in adolescent girls with different body mass index.

In the present quasi-experiments (QEs) study, which was conducted with pre-test and post-testdesign, 45 female students in the age range of 13 to 18 years old were selected and added to 3 groups of15 people with normal, overweight and obese body mass index. The training protocol included 10 weeksof aerobic training, 3 sessions per week and each exercise session for 20-45 minutes of. Pulmonary functionwas measured by spirogram and Maximal oxygen uptake (VO2max) by modified treadmill bulk test.

There were significant differences in Forced Vital Capacity (FVC), Forced Expiration Volume in oneSecond (FEV1), Peak Expiratory Flow (PEF), FEV1/FVC and VO2max in groups with normal body mass index,overweight and obese (P<0.001). After the training period, a significant improvement was observedin spirometry indices (FVC, FEV1, PEF, FEV1/VC) and VO2max compared to the pre-test (P <0.001), but stillsignificantly lower than the post-test values in the was normal group. Also significant decreased wasobserved in Body Mass Index (BMI) in obese and overweight groups (P<0.001).

The results of the present study showed that obesity is one of the effective factors in reducingpulmonary function and aerobic exercise improves pulmonary function and cardiorespiratory endurancein adolescent girls with different body mass index.

Myocardial ischemia leads to left ventricular (LV) dysfunction and cardiac arrhythmia. The present research was conducted with the aim to explore echocardiography changes and electrocardiogram parameters of the hearts of rats with ischemia-reperfusion injury (IRI).

The study subjects included 50 male Wistar rats) 8-10 weeks), which were divided into 5 groups (1: trained, 2: supplemented, 3: combined (training and supplementation), 4: sham, and 5: control). High-intensity interval training ‎(HIIT) was performed for 8 weeks, 5 sessions per week. Rats belonging to groups 2 and 3 received 10 mg/kg berberine. Finally, after 48 hours, electrocardiogram and echocardiography were performed on all rats. Moreover, myocardial ischemia was performed by descending coronary artery ligation for 30 minutes.

There were significant differences between the 5 groups in terms of the volumes and dimensions of LV end-systolic dimension (LVSD), LV end-diastolic dimension (LVDD)‎, fractional shortening cardiac output, ejection fraction (EF), stroke volume (SV), ventricular tachycardia (VT), and ventricular ectopic beats (VEBs) episodes, duration of VTs, and ECG parameters (P ≤ 0.05).

Berberine supplementation and HIIT, as preconditioning agents, can possibly prevent the elevation of EF and fractional shortening, the reduction of cardiac output and SV, and arrhythmia improvement after myocardial IRI. Finally, these changes result in increased LV function and decreased mortality in rats with myocardial IRI.

Type 1 diabetes is one of the most common chronic diseases in children. Theaim of this study was to determine the effect of eight weeks of regular exercise training and Ganodermasupplementation on glycemic control in children with type 1 diabetes.

In this quasi-experimental study, 40 boys with type 1 diabetes were selected anddivided into 4 groups: 1) exercise, 2) supplement, 3) exercise & supplement 4) control. Exercises included8 weeks, 3 sessions per week and each training session included selected exercises training. Ganodermalucidum consumption for daily consumption of 20 grams of a brewed drink was consumed. Fastingblood sampling was performed 48 hours before and 72 hours after the intervention.

A significant decrease was observed in 2Hour Post Prandial Glucose in the exercise & supplementgroup compared to the control group (P=0.018). Also Significant decrease was observed in HbA1c level inexercise (P=0.031) and exercise & supplement (P=0.043) compared to the control group.

According to the results, it can be said that combined exercise training can play an importantrole in the management of blood sugar in type 1 diabetes and the use of Ganoderma can increase theeffectiveness of exercise in blood glycemic control along with exercise training.

Obesity is a medical problem that increases the risk of health problems like diabetes. Hormones secreting from fat tissue, Leptin, are correlated with body mass index. Leptin reduces the personchr('39')s appetite by acting on specific centers of their brain to reduce their urge to eat. And insulin, a hormone produced by the pancreas, is essential for regulating carbohydrates and the metabolism of fat. A positive relationship between leptin levels and insulin resistance in children showing in this study is to determine the effect of continues-endurance and interval-endurance on leptin serum levels and insulin resistance in over-weighted youths.

This study is a semi-experimental design. Thirty boys were voluntarily selected as a matched two experimental groups and a control. Physical profiles included aged 16-19, BMI; 37.75 (±4.46) KG/M2, base functional capacity: 32.8 (±3.6) ml/kg/min which dividing by three equal groups: the submaximal training interval, a continuum and interval and control group performed the submaximal running program for six weeks on 3 D/W. The selected parameters were evaluated for an intervention pre and post-conditions.

weight and body mass index variables were decreased by about 2.5-3% after exercise intervention. Plasmatic leptin levels were reduced by about 45% in the continuum and interval control groups. HOMA-IR & QUICKI indexes altered in the EG (8.9 %, 7.8%) (P-value < 0.05).

Presumably, 2 exercise program patterns lower than lactate threshold could change body composition profile, basal leptin level, and blood glucose /insulin concentrations, which probably induced changes in resistance to insulin.

 Accurate and rapid measurement of cardiorespiratory system performance by estimation methods regardless of basic physiological fitness level, geographical environment, culture and nutrition is of paramount importance. The purpose of this study was to design linear regression equations to estimate the aerobic capacity of healthy adolescent boys without the use of sport tests and validation of this equations.

In the present semi-experimental study, 156 healthy adolescent boys aged 13 to 17 years with a mean body mass index of 21.43 ± 4.5 Kg / m2 were selected by purposive sampling method. To design the non-sport equation for estimating maximum oxygen consumption (VO2peak), a multiple regression linear model and Pearson correlation were used to validate the equations.

Significant correlations were observed between the measured VO2peak and the anthropometric and physiological variables (R=0.122 - 0.799, P<0.001). Also, a valid non-exercise linear equation for boyschr('39') VO2peak prediction was designed with variables such as age, BMI and resting heart rate (SEE = 3.59 mL/kg/min, R2 = 0.712, P<0.001). The estimated VO2peak from equations had a significant correlation with the obtained criterion value. (R = 0.707 – 0.730, P<0.01).

According to the results of the present study, it is possible to use aerobic capacity estimation equations, is a simple, accurate, safe tool in assessing the baseline cardiorespiratory fitness (VO2peak). The use of non-Exercise equations in the planning of exercise in large populations of adolescent boys and even as a daily clinical practice in the elderly and heart patients with the goals of promoting health, cardiovascular health, preventive actions is very important.

The effects of chronic exposure to isoflurane anesthetic gas at a concentration of 13 ppm on the function of cardiovascular and respiratory systems of hospital operating room staff are investigated in this study.

Methods and Materials:

 Subjects included operating room staff (experimental group: 10 men and 10 women) and control group has been selected from other wards of hospital both voluntarily and purposefully with the mean age of 35.8±5.29, work experience of 13.15±4.64, and the BMI is equal to 24.59±3.51 KG/M2 with daily step of 4124.35±1016.19 . First, eligible subjects have performed a 6MWDT cardiovascular function sub-maximal test. Then they have performed a jogging ablation program on a treadmill in a separate session. Spiro metric maneuvers were also performed (% FVC,% FEVC, FEVC / FVC) by KNUDSON method to measure pulmonary capacity.

The results of MANOVA statistical analysis showed that, in the situation without gender intervention, operating room staff in selected cardiovascular function indices were significantly lower than the control group (p <0.05). There was a significant difference in pulmonary indices and shortness of breath between the two groups (p <0.05). Considering gender factor intervention men and women had a significant differences in some cardiovascular and respiratory indices respectively (p <0.05).

Decreased cardiopulmonary function and dysphea during standard submaximal physical activity were more pronounced in operating room staff than in the control group. In contrast, women in the experimental group had lower respiratory tract efficiency than their control group counterpart.

 During recent decades, research studies have confirmed exercise training as a remarkable lifestyle intervention towards enhancing learning and memory. However, the intensity and manner by which the labor conditions partake in the functionality of brain tissue are not yet clear. Therefore, this study aimed to provide a non-systematic review article of the behavioral and cellular mechanisms on learning function and memory performance in animal and human species.

The method of data collection was to retrieve scientific papers, published between 1999 and 2019, from available databases, using the searching keywords: aerobic exercise, memory, and learning. Subsequently, out of 120 available articles, 107 cases were selected to survey the role of aerobic exercise on the nervous system.

 Findings from the literature review revealed the significant effect of regular submaximal aerobic exercise on learning and memory function, in both rats and humans. Furthermore, some studies indicated that long-term aerobic exercise intervention did not increase the learning functions and memory performance. Nevertheless, the positive effects of exercise patterns on memory predominate the negative ones. Thus, further investigation is necessary to thoroughly examine the role of the intensity, duration, and type of exercise training on both cognitive learning functions, and on the selection of new neuropeptides in brain tissue.

The rehabilitation role of aerobic exercise protocols seems important in the enhancement of learning level efficiency. Also these protocols were important in possible treatment of the memory-related central nervous system disorders.