فصلنامه فیزیولوژی ورزشی
پیاپی 39 (پاییز 1397)

The purpose of this study was to investigate the effect of High Intensity Interval Training (HIIT) on gene expression of Uncoupling Protein 1 (UCP-1) in subcutaneous white adipose tissue of wistar rats. For this purpose,24 rats were divided into three groups included: 1) Control (n=8) 2) Moderate volume HIIT (n=8) and 3) high volume HIIT (n=8). The subjects of training groups underwent two models of HIIT at different volume (moderate and high) for 8 weeks (5 sessions per week). Forty-eight hours after last training session, rats were euthanized and subcutaneous adipose tissue (inguinal depot) were quickly dissected out. The Syber Green Real Time–PCR method were used to measure the gene expression of UCP-1. One-way analysis of variance (ANOVA) was used to analysis of data by a p value of P

The objective of the present study was to investigate the changes in corticospinal excitability and motoneurones responsiveness of Biceps Brachii muscle during and within a time-course after submaximal fatiguing contractions. Eight active male (Age 29.6 ± 1.92 yrs., Height 181 ± 3.46 cm, Weight 78.3 ± 4.74) volunteered to take part in this study and reported to the laboratory on three different occasions. After measuring 1RM and familiarization with the experimental procedure in the session one, in the second and third visits, motor evoked potential (MEP) and cervicomedullary motor evoked potential (CMEP) were assessed immediately after each bout and 5-minute and 10-minute after the termination of the task by the use of magnetic stimulation over the motor cortex and spinal routes respectively. Three bouts of 3-minute (T1,T2,T3) elbow flexion and extension at 25% of 1RM separated by a 1-minute rest were used as the fatiguing task. Our results by the use of one-way repeated measures ANOVA showed a significant decrease in MEP after T2 (P₌0.006), T3 (P₌0.006), and after 5-minute (P₌0.000), during the recovery time. The results also indicated CMEP to significantly decline after T1 (P₌0.014), T2 (P₌0.008), and T3 (P₌0.010). It seems that both spinal and supraspinal mechanisms contribute to performance reduction in the submaximal fatigue. Moreover, it takes the CNS a longer time to recover from fatigue induced by submaximal contractions.

The aim of this research was to study the effect of different doses of licorice root with resistance training on blood glutathione peroxidase activity and total antioxidant capacity in sedentary and overweight men. In a semi-experimental trial with double-blind, 90 sedentary and overweight men were divided in six groups of fifteen people: (G1: NRT+SG250mg in the day, G2: NRT+SG500mg in the day, G3: SG250mg in the day, G4: SG500mg in the day, G5: NRT+P250mg in the day and G6: C+P250mg in the day). The resistance training program was conducted for 8 weeks and three sessions per week. Within-group results indicate a significant increase in glutathione peroxidase and total antioxidant capacity in the NRT+SG250mg (P=0.023), NRT+SG500mg (P=0.014) and NRT+P250mg (0.038) group. The highest percentage significant incremental changes of glutathione peroxidase (4.10%) and total antioxidant capacity (29.71%) was related to NRT+SG250mg group. Between-group results showed that there was incremental significant difference between the NRT+SG250mg, NRT+SG500mg, and NRT+P250mg with SG500mg, SG250mg and control groups in the mean concentration of glutathione peroxidase and total antioxidant capacity (P<0.05). Probably, performing resistance training along with taking licorice supplementation can be effective in enhancing the antioxidant status of sedentary and overweight men.

Depression is one of the most common psychiatric disorders. Probably doing exercise training before coping with stressful situations can affect the symptoms of depression. Due to a variety of exercise training methods, the present study aimed at investigating the protective effect of continuous and high intensity interval training on corticosterone, weight gain and behavioral despair in rats following a period of chronic unpredictable stress. For this purpose, 27 adult male Wistar rats (9 weeks, 200±20 g) were divided into continuous training, interval training, and sedentary group. The exercise training was progressive and included running on treadmill for five days per week within six weeks. Interval training was consisted of two to six two-minute periods with speed of 38 to 42 m/min and continuous training was 22 to 42 minutes with speed of 23 to 27 m/min. After the training period, the rats were exposed to stress for three weeks. Finally, forced swim test was performed and the plasma corticosterone level was measured. The weight of rats was measured every week. The results indicated that the continuous exercise training group had lower corticosterone and less immobility in forced swim than the control group. The rats of all three groups had significantly less weight gain during the stress period than the training period. In general, the continuous exercise had an acceptable protective effect on corticosterone secretion and despair. However, none of the exercise trainings could affect the improvement of weight gain.

Because of a compensatory appetite increase in response to exercise energy expenditure, the net weight loss is less than expected values in weight control interventions. Therefore, we investigated the acute response and adaptation of physiological and conceptual appetite indices and body weight to aerobic training in obese middle-aged and elderly women. Body weight, appetite, plasma glucose, insulin and ghrelin were measured before and after an aerobic exercise session following to a breakfast meal at baseline and after (four measurements) eight weeks of aerobic training (3 sessions/week by expending ~500 calories at 50% of GXT’s exhaustion HR) in 26 sedentary women (weight: 92.58 ± 36.9 kg, age: 56.19 ± 7.3 yrs and VO2max: 32.07 ± 2.78 Lit/min) were assigned into experimental and control groups. Independent and paired t-test, and analysis of variance with repeated measures were used to analyze the data. Although body weight in experimental groups was decreased after aerobic training (P=0.001), however; it was elevated from first to second and also from third to fourth measurements in both groups (P<0.05). Before the training period, plasma ghrelin was elevated after breakfast and an exercise session in the experimental group (P=0.023), however, it was decreased in the control (only served breakfast) group (P=0.001). In both experimental and control groups, insulin (P=0.001) and glucose (P=0.003) increased, while hunger decreased (P=0.001). After the training period, the satiety score increased significantly only in the experimental group (P=0.018). Acute response in the experimental group increased for glucose (P<0.05) and decreased for ghrelin, insulin and hungry (P<0.05). However, in the control group, acute glucose and insulin response increased (P<0.05), but ghrelin and starvation decreased (P<0.05). Training-induced fasting hungry elevation failures the fully achievement to net weight loss expected form training, which suggests including lesser calorie foods in the breakfast meal. Additionally, considering the acute increase of food satiety quotient by exercise, it seems the breakfast meal should be postponed for the end of exercise session.

The prevalence, incidence, and morbidity of cardiac diseases increase with aging. Cardiomyocyte apoptosis contributes to the pathogenesis of heart failure. The aim of this study was to evaluate the effect of 12 weeks resistance training and green tea extract on cardiac caspase 3 expressions and telomerase enzyme content in aged male rats. In this study, 20 aged male rats were randomly divided into four groups: control, exercise, supplement and exercise plus supplement. Exercise groups performed resistance exercise for 12 weeks and five days per week; meantime, the supplementary groups consumed green tea extract. Immunohistochemistry method was used to measure the expression of caspase 3 and sandwich ELISA method was used to measure the telomerase content. Data was analyzed by ANOVA and Tukey's post hoc test .The results show that caspase 3 expressions in exercise (P=0.011), supplement (P=0.001) and exercise plus supplement (P=0.000) groups was significantly lower than control group. caspase 3 expressions in exercise plus supplement group significantly lower than exercise group (P=0.004) and supplement group (P=0.031). Telomerase content in exercise (P=0.043), supplement (P=0.015) and exercise plus supplement (P=0.005) groups was significantly higher than control group. According to the results of this of this study, the combination of resistance training and green tea extract can prevent cell aging in the cardiac tissue of elderly rats with decreasing expression of Caspase-3 and increased content of telomerase enzymes in the cardiac tissue.

The purpose of this study was to investigate the effect of aerobic exercise and consumption of stevia extract on glycemic indices, insulin resistance and beta cell function of diabetic rats. In this study, 35 male Wistar rats with an average weight of 188.86 ± 15.8 g were randomly divided into 4 groups (diabetic control, diabetic exercise, diabetic extract and diabetic exercise with stevia). Aerobic exercises included running on the treadmill, 5 days a week for 6 weeks and the extract receiving was continued for the same period. At the end of the intervention, glucose and insulin levels were measured to evaluate the HOMA-IR and HOMA-β indices. The results showed that the aerobic exercise program and stevia extract significantly decreased glucose levels and significantly increased HOMA-β in the experimental groups compared to the diabetic control group (P <0.05). Insulin resistance levels were lower in the experimental groups than the diabetic group, but this difference was not statistically significant (P > 0.05). It can be concluded that the aerobic exercise and the consumption of stevia extract alone and in combination with together, can lead to significant improvement in glucose levels and pancreatic β-cells function in diabetic rats. Meanwhile, extract consumption along with aerobic training in comparison to training and stevia extract consumption alone can have greater impact.

The purpose of this study was to predict the time to exhaustion based on some physiological and anthropometric parameters in young men. A total of 75 male students (20.74±1.22 years, 67.25±10.78 kg, and 174.3±0.06 cm) were selected using convenience (availability, maximal oxygen uptake 47/1±3/29 ml/kg/m-1) sampling. Firstly, anthropometric variables and physiological parameters involving lactate threshold, aerobic and anaerobic power, resting heart rate, physical activity, velocity at maximal oxygen uptake, lower-body endurance as well as strength and lower-body explosive power were measured. Also, to measure the heart rate, O2 saturation and running time, all subjects participated in a bout of treadmill running to exhaustion at four different speeds (8, 10, 12, and 14 km/h-1), with slope set at zero. The results show the velocity at maximal oxygen uptake, heart rate, resting heart rate, physical activity, and lower-body explosive power predicted time to exhaustion at a speed of 8 km/h-1(P≤0.05). The velocity at maximal oxygen uptake, running history, resting heart rate, V. lactate, and weight predicted time to exhaustion at a speed of 10 km/h-1 (P≤0.05),V. lactate, running history, weight, resting heart rate and maximum power time to exhaustion at a speed of 12 km/h-1 (P≤0.05), Thevelocity at maximal oxygen uptake, physical activity, weight, maximum power, and running history were the prediction factors of time to exhaustion at a speed of 14 km/h-1 (P≤0.05). The velocity at maximal oxygen uptake, resting heart rate and running history were common at most speeds. According to the results of time to exhaustion, the velocity at maximal oxygen uptake, running history, resting heart rate, and lactate thresholds can be used.

Potential benefits of local cold application during exercise include reducing blood flow, delaying fatigue, and providing analgesic effects. The purpose of this study was to investigate the effect of 8-weeks local muscle cooling during resistance training on Knee Extensor (KE) strength, hypertrophy and muscle activation. In this experimental study, twelve recreationally-trained male and female (age, 24.1±3.5 years; weight, 69.3±18.8 kg; height, 175.2±12.7 cm) were divided equally into two groups: RT and RT-Cold. Both groups completed an eight-weeks progressively resistance training (seated Leg Curl and leg press, 4 sets, 6-12 rep, 70-85% 1RM, 3 sessions per week). A cold compression device (Cryo-cuff, Aircast) was placed on the subject's thigh for 25 min before and during resistance training with different temperatures (25° for RT and 10° for RT-Cold). Dynamic strength (1RM), knee extensor muscles cross-sectional area (CSA), and muscle activation (normalized RMS of EMG) were measured at baseline and after 8-week. Differences between the RT and RT-Cold groups were tested using analysis of covariance at the level of P≤0.05. The improvements in 1RM strength were not significantly different between RT and RT-Cold groups (P˃0.05). In terms of the muscle activation, there was not any significant difference in mean RMS of knee extensor muscles between groups. Ultrasound measurement of CSA also showed that the CSA of cooled limb in RT-Cold significantly greater than those in RT group. These results would indicate that local muscle cooling improve resistance training-induced hypertrophy, whereas this technique did not affect muscle strength and activation.

Aging is associated with changes in blood cholesterol and subsequent cardiovascular disease. The purpose of this study was to investigate the effect of continuous and interval endurance training on micro-RNAs associated with reverse cholesterol transport in Wistar elderly rats. 30 male Wistar rats (23-month-old) With an average weight of 441.75 gram, were randomly divided into two experiment and one control group including continuous training (n = 10), Interval training (n = 10) and the control group (n = 10). Continuous and interval exercise included 8 weeks of training on treadmill and 5 days a week which the continuous group started training with 60% maximum speed for 16 minutes in the first week and continued with 70% maximum speed for 45 minutes from the fourth week to the end of the eighth week. The interval group started exercise at 40-80% of the maximum speed from the first week and continued at 30 to 110% of the maximum speed from the fourth week to the end of the eighth week. After completing training, expression of miR-33 and miR-144 and mRNA expression of ABCA1 were measured RT-PCR. The statistical analysis was performed using ANOVA test with significance level (P <0.05). The expression of miR-33a and miR-144 decreased in both continuous and interval groups compared to control group, but this decrease was only significance for miR-33a (P <0.001). After 8 weeks of training, mRNA expression of ABCA1 gene in the continuous and interval group increased compared to control group. However, this increase was statistically significance only for the interval group (P=0.002). There was no statistically significance difference between the effect of interval and continuous exercises on miR-33a and miR-144 expression. However, there was a significance difference in the mRNA expression of ABCA1 in both continuous and interval groups (P=0.028). Considering the results, it appears that both continuous and interval endurance trainings can decrease miR-33a expression and subsequently increase mRNA expression of the ABCA1, which this increase is higher in interval training compare continuous training.