فصلنامه فیزیولوژی ورزشی
پیاپی 47 (پاییز 1399)

The purpose of this cross-sectional present study was to investigate the force-related fatigability in gymnast and untrained girls according to tanner stage. 60 gymnasts and untrained girls were divided into the three subgroups of children, adolescents and adults according to Tanner's scale. Subjects were referred to the laboratory in three separate sessions for familiarity and initial measurements, maximal test, and fatigue test, respectively. For the maximal test, each subject performed three maximum isometric contractions of the knee extensor at five different angles to determine the optimal angle of force production. The fatigue test included repeating five-second maximum contractions with five seconds of rest to reach 60% of maximum torque. The electrical activity of the rectus femoris muscle was recorded using an electromyography to measure mean power frequency (MPF). Two-way ANOVA was used for data analysis. There was a significant difference between the number of repetitions to fatigue in children compare to adolescent and adult (P<0.05), this difference (between children with adolescents and adults) was not significant in gymnast groups (p>0.05). However, the normalization of the torque drop based on the initial productive force (peak torque) showed a similar pattern in children and adults. This may indicate the importance of the peak torque in explaining fatigability between children and adults. It seems gymnastic training in pre-puberty period may shift the fatigability pattern toward adulthood pattern.

The risk for nonalcoholic fatty liver (NAFLD) disease is directly related to the body mass index, with obese children being most at risk for NAFLD. The main aim of this study was to evaluate the changes in some liver enzymes and lipid profile of adolescents with fatty liver, following a selected school based and high intensity interval training. Thirty adolescent boys (aged11-14year) with obesity (based on ≥95th percentile of body mass index and age growth chart) and clinically defined as NAFLD disease were divided equally into the high intensity interval training (BMI; 26.51±1.83kg/m2, n=10), and selected school-based exercises (BMI; 26.69±2.45kg/m2, n=10). Hepatic ultrasonography, VO2peak, lipid profile, insulin resistance, AST and ALT levels of subjects were measured before and after the SBE (45-60 min. selected exercise and games) and HIIT (36-40 min Running at 100-110 maximum aerobic speed) protocols. ANCOVA statistics was used to analysis of data and results showed that there was a significant increase in VO2peak of groups after exercise intervention (P=0.001). Also, there were significant reductions in insulin resistance (P=0.01), triglyceride, alanine amino transferase and aspartate amino transferase levels in both groups (P=0.01). HDL levels increased significantly only in SBE group (P=0.048), but there were no significant differences between LDL levels of groups (P=0.250). Therefore, we concluded that both selected school based and high intensity interval training protocols were equally effective in improving some health parameters in children with obesity and fatty liver.

Decline in catecholamine levels is an effective factor in occurrence of Attention deficit hyperactivity disorder (ADHD). The purpose of this study was to investigate the synergistic effect of 12-week aerobic training, yoga and omega-3 consumption on hyperactivity and urine catecholamine levels in 7-11 years old hyperactive students. 43 students were randomly assigned to healthy control (n=8), HDAD control (n=9), HDAD omega-3 (n=9), HDAD exercise (n=9), HDAD exercise+omega-3 (n=9) groups. Exercise groups performed 12 weeks of aerobic and yoga training (Every week for long five 60-minute sessions) and supplementation groups consumed omega-3 supplement (1200 mg). Urine epinephrine and norepinephrine levels and degree of hyperactivity were measured before and after the study, and were compared between groups using analysis of covariance (ANCOVA). At the beginning of the study, the levels of epinephrine and norepinephrine in the HDAD control group were significantly lower than the healthy control (P<0.01). At the end of the study, epinephrine levels in the omega-3 group (P<0.01), norepinephrine levels in the exercise group (P<0.01), and both norepinephrine and epinephrine levels in exercise+omega-3 group were significantly higher than the ADHD control group. Post values of hyperactivity in the omega-3 group (P<0.01), exercise group (P<0.01), and exercise+omega-3 group (P<0.01) were significantly lower than the ADHD control group. Post values of hyperactivity in the exercise+omega-3 group were also significantly lower than the exercise group (P<0.01). In conclusion, the present study showed that omega-3 consumption and aerobic training improve hyperactivity with increasing epinephrine and norepinephrine levels, respectively, and simultaneous implementation of these variables exaggerate these beneficial effects.

The purpose of this study was to investigate the effects of eight weeks of aerobic and resistance exercise on the levels of alpha and beta salusins, and inflammatory indices in type2 diabetic women. For this purpose, 45 volunteer participants were randomly assigned to the three groups of 15, including aerobic exercise, resistance exercise, and control. Resistance and aerobic exercises were performed three times a week for eight weeks with a gradual progressive manner. Resistance training consisted of 8-12 repetitions at 60-70% of 1RM, and aerobic training consisted of 30-50 minutes of running on a treadmill at 65-75% of maximum heart rate. Before and after the intervention period, serum levels of alpha and beta salusins, malondialdehyde and IL-1β were measured. The results showed significant decrease in salusinβ levels in both aerobic (P=0.015) and resistance (P=0.019) groups. In the other side, the levels of salusinα were significantly increased in aerobic (P=0.034) and resistance (P=0.012) groups. In addition, the IL-1β levels were significantly decreased in both aerobic (P=0.034) and resistance (P=0.041) groups. However, the levels of malondialdehyde had no significant changes in any group. The level changes of salusinα, salusinβ, and IL-1β were not significant between the aerobic and resistance groups. According to the results of the present study, performing eight weeks of resistance or aerobic training can positively affect the levels of salusinα, salusinβ and IL-1β in women with type2 diabetes.

The purpose of this study was to determine the effect of six months resistance training (RT) and two weeks subsequent detraining on orexin and lipid profile in obese men. Thirty sedentary men (age: 21± 1.7year, height: 175.5± 5.7 cm and weight: 95.75± 5.35 kg) were randomly assigned into RT (7 movements, 4 sets of 8 repetitions with 80% 1-RM, 3 sessions per week for six months) and control group involving 15 people in each group. Blood samples were obtained in the pre-test, 48 hours, 8, 16 and 24 weeks following RT and after 2 weeks detraining. The ANOVA with repeated measure showed one session RT had no effect on variables. Serum concentration of orexin (P=0.005) after 24 weeks, LDL (P=0.004, P=0.001 and P=0.001), TG (P=0.020, P=0.012, P=0.002), weight (P=0.001, P=0.001, P=0.001) after 8, 16 and 24 weeks, and TC (P=0.025, P=0.002) after 16 and 24 weeks of RT were lower in RT compared to the control group, respectively. HDL (P=0.001, P=0.001, P=0.001) was higher in the RT compared to the control group after 8, 16 and 24 weeks of training. Compared to the last training session, two weeks of detraining increased weight (P=0.014), LDL (P=0.002), TG (P=0.006), while HDL reduced (P=0.001), but they were still better than the pre-test. At all, RT in addition to affecting the orexin, can improve body weight and lipid profile in obese men and by increasing the duration of training, changes in the variables were more perceptible. Although, these adaptations are weakened by detraining.

The aim of this study was to investigate the effects of eight weeks of high intensity interval training (HIIT) on gene expression of PPARγ and liver TG in rats with nonalcoholic fatty liver disease. In this experimental study, thirty male Wistar rats were randomly divided into two groups. The first group (20 rats), consumed 16 weeks a high-fat diet with the aim of create a fatty liver, and the second group (control), (10 rats), consumed standard diet during this period of time. After confirmation of fatty liver by measuring the serum level of ALT enzyme in the first group, they were randomly divided into two groups of NAFLD and NAFLD+HIIT (each group of 10 rats), the NAFLD+HIIT group performed progressive exercise training for eight weeks, according to percentage of maximum speed (75-90 percent) and the NAFLD and control groups only took their diet and did not participate in any exercise. After eight weeks of exercise training, expression of PPARγ and TG level were measured. Data analysis showed a significant increase in PPARγ expression in the NAFLD+HIIT group compared to the NAFLD group (P=0.001). Liver triglyceride in NAFLD+HIIT group had a significant decrease (P=0.001). On the other hand, the mean weight of rats in the NAFLD + HIIT group did not change significantly (P= 0.054), but the mean weight of control and NAFLD groups increased significantly during this period (P=0.001). It seems that high intensity interval training by increasing in expression of PPARγ and its effect on the regulation of the expression of effective genes in fat metabolism, independent of weight loss, can reduce liver TG and improves fatty liver disease.

The purpose of this study was to measure the changes in oxidized (GSSG) and reduced (GSH) glutathione, glutathione reductase (GR) and glutathione peroxidase (GPX) after repeated-sprint activity (RSA) and subsequent cold water immersion (CWI). Twenty trained athletes with maximal oxygen uptake (VO2max) 52.9±2.9 ml.kg-1.min-1, age 21.9±2.2 yrs, height 174.2±5.4 cm, and weight 68±4.4 kg was assigned to take part in this study. After performing repeated-sprint activity, 10 participants immersed in cold water (14°c) and 10 participants passively sat on a chair at room temperature. Blood sampling was performed before and after RSA, after CWI or passive rest and after 24 h. The blood variables assessed through ELISA method. The results showed that antioxidant levels did not return to baseline levels and CWI had no effect on these factors, compared to GPX and GR returned to baseline levels after 24 h, nevertheless; there was no significant difference between CWI and Control groups. In conclusion, although the levels of enzymatic and non‐enzymatic antioxidants were significantly higher after RSA, CWI did not have any effect on returning to baseline levels after 24h.

One the major reason of the age-related muscular atrophy, Sarcopenia, is neurogenic atrophy. Despite this issue, the effects of some pathway which have probability effect, such as: kind of training methods, especially high interval intensive training, on the main factors of the neurogenic cascades is not yet clear. Therefore, the aim of this study was to investigate the effects of high interval intensive training period on the expression of the HDAC4, HDAC5, Dch2 and Myogenin gens in the plantaris muscle of the aged male Wistar rats. 28 male Wistar rats randomly assigned in to four groups (N=7, adult control, N=7, adult training, N=7, aged control, N=7, aged training). The training group performed HIT 5 times per week for 6 weeks. 48 hours after the end of the last session of training with control group were anesthetized and sacrificed. Then the plantaris muscle was removed. Real time PCR method was used to determine the gene expression levels of HDAC4, HDAC5, Dch2 and Myogenin. For the statical analyses two-way ANOVA and Tukey were used. The statical significant assumed P≤0.05. The results of this study have been shown that HDAC4, HDAC5 and Myogenin significantly decreased. The amount of the Dch2 increased significantly compared to young control group. According to the results of this study, it seems high interval intensive training suppress the neurogenic atrophy   in the orders adult.