The effect of combined exercises on the plasma levels of retinol-binding protein 4 and its relationship with insulin resistance and hepatic fat content in postmenopausal women with nonalcoholic fatty liver disease.

BACKGROUND: Evidence suggests increased serum levels of retinol-binding protein 4 (RBP4) in postmenopausal women with nonalcoholic fatty liver disease (NAFLD). This study investigated the effect of combined exercises on the plasma levels of RBP4 and its relationship with insulin resistance and hepatic fat content in these women. METHODS: This quasi-experimental study randomly assigned 24 women with fatty liver and a mean age of 56.18±4.58 years to an experimental group and a control group. The experimental group participated in ten-week incremental endurance-resistance training as combined exercises three sessions a week. Fatty liver was diagnosed with ultrasound, RBP4 levels were measured, and insulin resistance was determined using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Between-group data were analyzed using ANCOVA, within-group data using the dependent t-test and Wilcoxon test and relationships between RBP4 and variables using Spearman and Pearson correlation coefficients. RESULTS: Ten weeks of combined exercises significantly decreased RBP4 levels (P=0.000), HOMA-IR (P=0.011) and hepatic fat levels (P=0.000) in the experimental group compared to in the controls. The Post-test showed significant correlations between RBP4 levels and hepatic fat levels (P=0.002) and no correlations between RBP4 levels and insulin resistance (P=0.116). CONCLUSIONS: Combined exercises significantly reduced serum levels of RBP4 in postmenopausal women with fatty liver. RBP4 was not related to insulin resistance and effects of RBP4 on hepatic fat regulation were independent of the effects of insulin resistance.

Effect of forced treadmill exercise on stimulation of BDNF expression, depression symptoms, tactile memory and working memory in LPS-treated rats.

Neuroinflammation has been implicated in cognitive dysfunction and the occurrence of depression in neurodegenerative diseases. Brain-derived neurotrophic factor (BDNF) is believed to be involved with the benefits of exercise training in boosting memory and learning processes and antidepressant therapies. This study aimed to investigate the effect of forced treadmill exercise on hippocampal BDNF expression levels, depression symptoms, tactile memory and working memory in lipopolysaccharide (LPS)-treated rats. For this purpose, 40 male Wistar rats received 0.25 mg/kg of LPS or saline intraperitoneally for 9 consecutive days before exercise. They again received a single injection of 0.5 mg/kg of LPS or saline on days 20 and 41 after exercise. Exercise groups had to run on a motorized treadmill 5 days a week for 8 weeks. Following the last exercise training session, forced swim test (FST), Y maze and novel object recognition (NOR) task were performed. Finally, the hippocampus of rats was removed and used for determination of BDNF expression levels by real-time polymerase chain reaction (real-time PCR). The data showed that LPS decreased BDNF expression levels, Y maze score, and recognition index in NOR and increased immobility time in FST (p < 0.05). In contrast, forced treadmill exercise increased BDNF expression levels and improved the percentage of spontaneous alternation, recognition index, and immobility time in LPS-treated rats (p < 0.05). There was a significant correlation between BDNF expression levels with immobility time and recognition index (p < 0.05) but not with the percentage of spontaneous alternation (p > 0.05). The findings suggest that forced treadmill exercise may protect the brain of LPS-treated rats by improving the symptoms of depression and cognitive function through its effect on BDNF expression levels.

Effects of Eight Weeks of Resistance Exercises on Neurotrophins and Trk Receptors in Alzheimer Model Male Wistar Rats.

INTRODUCTION: This study evaluates the effects of 8 weeks of resistance exercises on the expression of neurotrophins and Trk receptors in Alzheimer model male Wistar rats. METHODS: For this purpose, 32 mature male Wistar rats with a mean weight of 230-280 g were chosen and divided into Alzheimer and Sham groups. The rats in the sham group received normal saline, while the ones in the Alzheimer group received streptomycin via intraventricular injection. These rats were then divided into the following four subgroups: 1) resting sham, 2) exercising sham, 3) resting Alzheimer, and 4) exercising Alzheimer. The two exercising rat subgroups exercised three times a week for 8 weeks. A weight was attached to their tails, and they had to carry it on a 26-step ladder in each cycle. Resting groups were handled every day to minimize the effects of stress. At the end of the eighth week and 24 hours after the last exercise session (to avoid the effects of the last exercise session), the rats were put under deep anesthesia and beheaded. Hippocampus tissues were precisely extracted, and samples were sent to the laboratory for molecular and cellular tests. To investigate gene expression, quantitative RTPCR was used. RESULTS: The tests for comparing the mean values of BDNF, NT3, NGF, TrkA, and TrkB in two rat groups showed that with error levels of less than 5%, there is a significant difference in the amounts of BDNF, NT3, NGF, TrkA, and TrkB between exercising rats and resting ones. These amounts were much higher in the exercising Alzheimer rats group. CONCLUSION: Eight weeks of resistance exercises increased the expression of BDNF, NT3, and NGF genes and TrkA and TrkB receptors in Alzheimer model Wistar rats.

Acute interval walking with blood flow restriction could not increase ERK, p38 and decrease myostatin.

BACKGROUND: There is mounting evidence that moderate to high intensity exercise training has a key role in skeletal muscle adaption. Blood flow restriction (BFR) low intensity exercise training associated with unique effect on muscle hypertrophy. The purpose of the study was to investigate of effect of acute interval walking with blood flow restriction on phosphorylation of 4EBP1, P38, ERK and myostatin (MSTN) of skeletal muscle in inactive men. METHODS: Five healthy inactive men were participated in 2 sessions with 14 days interspersed. Session one was including BFR by 5 intervals 3-min walking at 55%Maximum heart rate (MHR) and 1 min at rest. Session two was including 5 intervals 3-min walking at 55% MHRand 1 min at rest without BFR. All samples were collected at 30 min and 3 h after exercise test. Concentration of P38, ERK and MSTN skeletal muscle were evaluated by Western blotting. Dependent t-test and Independent t-test was used to analyze the data after subtracting the post-test score from the pre-test. However, there was a significant difference between the pre and post-test for 4EBP1 (P=0.001) and ERK (P=0.049) in the blood flow restriction group. RESULTS: There was no significant difference between pre and post-test of P38 (P=0/452). Significant difference was observed for ERK (P=0.012) in acute interval walking (P=0.049). There was no significant difference between pre and post-test of 4EBP1 (P=0.064) and P38 (P=0/122). No significant difference was found between two group for concentration of 4EBP1 (P=0.068), P38 (P-0.091) and ERK (P=0.827), (P≥0.05). CONCLUSIONS: This study has shown that acute interval walking with blood flow restriction does not activate MAPK pathway signaling in inactive men.

Treadmill exercise improves LPS-induced memory impairments via endocannabinoid receptors and cyclooxygenase enzymes.

Endocannabinoid system and cyclooxygenase enzymes are implicated in neuroinflammation-induced cognitive impairment. It is believed that non-pharmacological treatments such as physical exercise affect neural systems that control behavioral responses. This research examined the effects of treadmill aerobic exercise on the expression of cannabinoid receptors and cyclooxygenases against LPS-induced cognitive disorders in the hippocampus tissue of rats. For this purpose, rats received intraperitoneal injection of 0.25 mg/kg LPS or saline for 9 continuous days before exercise training. They again received a single i.p. injection with 0.5 mg/kg LPS or saline on days 20 and 41 after the beginning of exercise. The exercise groups were forced to run on a motorized treadmill 5 days per week for 8 weeks. After the last exercise training session, the water maze test was conducted to measure cognitive function. Finally, the hippocampus tissue samples of rats were removed and used to determine the levels of gene expression using the Real-Time PCR method. Data showed that the LPS-treated rats had longer escape distance and longer escape latency to reach the hidden platform and they spent less time than the other groups in the target quadrant, but exercise training improved them in the LPS + Exe (LPS + exercise) group. Exercise increased the expression of CB1 receptor in the Sal + Exe (saline + exercise) group and reduced the expression of CB2 receptor, COX-2 and mPGES-1 in the LPS + Exe group compared to the Sal + LPS group. The findings indicate that treadmill exercise may be beneficial for improvement of cognitive function by modulating the neuroinflammatory processes.

Assessment of airway resistance in normal trained and fat untrained adolescent boys influenced by exercise experiences.

BACKGROUND: Overweight and obese children are at increased risk of a wide range of health conditions including respiratory diseases. In addition, inactivity can decrease pulmonary function. This study assessed the effect of obesity and inactivity on pulmonary function impairment in adolescents. MATERIALS AND METHODS: This study was conducted on 80 adolescents. Subjects were divided into two groups. Group I included 40 untrained (VO2max= 29.30±4.20) fat adolescents (UO). Group II included 40 healthy trained (VO2max= 58.11±2.23) normal weight adolescents (TN). Body mass index (BMI), body fat percentage and waist to hip ratio (WHR) were calculated and pulmonary function tests were carried out according to the standard protocols. Data were analyzed using student's "t" test and Pearson's correlation coefficient. RESULTS: UO had significantly lower pulmonary function values than the TN group. They also showed lower FEV1/FVC ratio when compared to TN group (P < 0.05). In UO group, BMI, body fat percentage and WHR had a significant negative correlation with pulmonary function whereas in TN group only BMI had significant negative correlation with pulmonary function. A significant decrease in FEV1 was observed in the two groups, which led to a decrease in FEV1/FVC% after the exercise compared to before. Thus, exercise test induced airway resistance in both groups. CONCLUSION: untrained obese adolescents have more respiratory symptoms than their normal weight trained peers, and these factors are recommended to be used as a predictor of pulmonary function in assessment of obese children in epidemiological studies. In addition, obesity and inactivity can surcharge pulmonary function abnormalities in adolescents.

The Effect of High Intensity Interval Exercise in High / Low Temperatures on Exercise-Induced Bronchoconstriction (EIB) in Trained Adolescent Males.

BACKGROUND: Exercise-induced bronchoconstriction (EIB) describes airway narrowing that occurs in association with exercise. Exercise in hot and cold environments has been reported to increase exercise-induced bronchoconstriction (EIB) in subjects with asthma. However, to our knowledge, the effect of hot and cold environment on pulmonary function and EIB in trained males has not been previously studied. The main goal of this research was to examine the influence of environmental temperature and high intensity interval exercise on pulmonary function in trained teenage males. Also, this study sought to assess the influence of exercise and environmental temperature on EIB. MATERIALS AND METHODS: Thirty trained subjects (mean age 16.56±0.89 yrs, all males) underwent high intensity interval exercise testing (22 minutes) by running on a treadmill in hot and cold environments under standardized conditions (10 °C and 45 °C with almost 50% relative humidity in random order in winter and summer). Lung function (flow volume loops) was measured before and 1, 5, 15, 30 and 60 min after the exercise by digital spirometer. Data was analyzed using SPSS software and P < 0.05 was considered significant. The diagnosis of EIB was made by 10% fall in FEV1 post-exercise. RESULTS: The post-exercise maximal reduction in forced expiratory volume in 1s (FEV1), peak expiratory flow (PEF) and average forced expiratory flow rate over the middle 50% of the FVC (FEF25-75) increased significantly compared to pre-exercise at 10 °C with almost 50% relative humidity (cold air). The obtained values were: -15.93(15min post-exercise), -22.53 (1 min post-exercise) and -18.25%(5min post-exercise). Post-exercise maximal reduction in FEV1, PEF and FEF25-75 increased significantly compared to pre-exercise value at 45 °C with almost 50% relative humidity (hot air). Obtained values were: -10.35 (1 min post-exercise), -9.16 (1 min post-exercise) and -7.39 (5 min post-exercise). Changes in FEV1, PEF and FEF25-75 reduction in cold air was significantly greater than in hot air (P < 0.05). Maximal prevalence of exercise-induced bronchoconstriction (EIB) in cold and hot air was 60% (18 of 30 subjects) and 40% (12 of 30 subjects), respectively. CONCLUSION: This study demonstrated that pulmonary function in hot and cold air was influenced by temperature (in the same relative humidity (50%) and also high intensity interval exercise. Prevalence of EIB after high intensity exercise in hot and cold air increased in trained adolescent males; however, these changes in cold air were greater than in hot air among trained adolescent males. Therefore, results of this study suggest that adolescents (although trained) should avoid high intensity (95% maximal heart rate) exercise in winter (extremely low temperature) and summer (extremely high temperature) to prevent EIB.

Study and influence of exercise program on respiratory function of adults with kyphosis.

Adolescent idiopathic kyphosis causes not only spinal deformities but also rib cage abnormalities that lead to abnormal residual volume and pulmonary capacity revealed in pulmonary function testing (PFT). The objective of this study was to analyze the impact of a physical activity program on respiratory function in surgical patients with kyphosis. From October 2006 to October 2007, a total of 34 patients (age range, 22 to 42 years) with kyphosis and a thoracic curvature between 45 and 88 were examined prospectively at a sports medicine clinic belonging to National Iranian Oil Company (N.I.O.C.). The patients underwent clinical and radiographic examinations of the vertebral deformity, chest radiography, PFT, evaluation of peak expiratory flow rate, and 6-min walk tests (6MWTs) before and after joining a physical activity program for 4 months. The improvements in FVC, inspiratory capacity, FEV1, expiratory reserve volume, and performance assessed by 6MWT were observed after activity. General condition of patients improved after the exerscise program. This was reflected by both PFT and 6MWT results.