Effects of Six Weeks of Modified and Standard Nordic Hamstring Exercises on Electromyography of Hamstring, Hip And Trunk Muscles and Sprint Performance in Young Male Football Players

Background and Aims hamstring injury is the most common injury in football. Nordic hamstring exercise (NHE) is one of the best hamstring injury prevention strategies. This study was aims to compare the effect of six weeks of standard NHE and modified NHE on electromyography of hamstring, hip and trunk muscles and sprint performance in young male football playersMethods In this study, participants were 26 male football players in Kerman, Iran who were selected using purposeful and convenience sampling methods and randomly divided into two groups of NHE (Age: 16.31±0.51 years, Height: 173.08±5.15 cm, weight: 59.85±5.71 kg) and modified NHE (Age: 16.41±0.54 years, Height: 173±6.84 cm, weigh: 64.20±8.76 kg). Sprint performance was measured by the 20-meter sprint test, and muscles activity was measured by electromyography. Repeated-measure analysis of variance was used for data analysis.Results In the modified NHE group, there was a significant difference between the pretest and posttest phases in the electrical activity of biceps femoris (P=0.001), semitendinosus (P=0.001), gluteus maximus (P=0.016) and erector spinae muscles (P=0.001). In the NHE group, although the activity of muscles increased by 13% in the biceps femoris, 11% in the Semitendinosus, 9% in the gluteus maximus and 4% in erector spinae muscles, the difference was significant only in the biceps femoris (P=0.001) and Semitendinosus (P=0.024). The results also showed a significant difference between the two groups in electrical activity of biceps femoris (P=0.021), semitendinosus (P=0.046) and erector spinae muscles (P=0.039). Conclusion Both standard and modified NHE are effective in preventing hamstring injury by increasing the electrical activity of the Biceps femoris and Semitendinosus, but the modified NHE is more effective in prevention of injury by changing the parameters of NHE and increasing the training load

Exercise-induced Oxidative Shift of Lactate Dehydrogenase Isoforms in Cerebrospinal Fluid of Male Wistar Rats

Abstract Background: The aim of the present study was to investigate the effect of endurance training on the content of lactate dehydrogenase isoforms (LDHA and LDHB) and isozymes in cerebrospinal fluid of male wistar rats. Materials and Methods: Seventeen animals (5 weeks old) were randomly divided into two groups according their body weight: control (C; n = 9) and trained (T; n = 8). The animals from the T group were underwent a training program for 12 weeks (started at 20 m/min for 30 min and finished at 26 m/min for 60 min at the last week). Cerebrospinal fluid (CSF) samples were collected from cisterna Magna 72 hours after the last exercise session. LDH Isoforms and isozymes were measured by ELISA and Electrophoresis techniques, and the comparisons between groups were evaluated by student t-test. Results: Both LDHA and LDHB isoforms were found in the CSF of the C group; LDH1 and LDH5 had the highest and lowest content, respectively. Following the twelve-week training protocol, LDHB (p<0.01), LDH1 (p<0.01), and LDH2 concentrations (p<0.01) were significantly increased in the T group compared with those from the C group and LDH3 concentrations (p<0.01) and LDHA/LDHB ratio (p<0.01) were significantly decreased. Endurance training had no effect on LDHA and LDH4. Conclusion: Endurance training is associated with oxidative shift of lactate dehydrogenase isoforms and isozymes in cerebrospinal fluid which could be considered as a prelude to aerobic metabolism of lactate in the brain

Endurance training and MitoQ supplementation increase PERM1 and SMYD1 gene expression and improve hemodynamic function in cardiac muscle of male Wistar rats

Background:The histone methyltransferase (SMYD1) and the muscle-specific protein (PERM1) play an important role in maintaining cardiac energetics and function. The present study aimed to examine the effect of two types of endurance training (running and swimming) plus MitoQ supplementation on gene expression of PERM1 and SMYD1 plus hemodynamic function in the cardiac muscle of male Wistar rats.Methods: The animals underwent MitoQ supplementation or endurance training or endurance training + MitoQ supplementation for eight weeks. Gene expression of PERM1 and SMYD1, measured by Real Time-PCR and quantified by 2-∆∆CT method, and hemodynamic function were compared between groups using two-way multivariate analysis of variance. Results: Cardiac gene expression of PERM1 and SMYD1 increased significantly through running (PERM1, P < 0.05; SMYD1, P < 0.01), swimming (PERM1, P < 0.05; SMYD1, P < 0.05). and MitoQ supplementation (PERM1, P < 0.001). The effects of MitoQ supplementation were additive to both running and swimming effects on cardiac gene expression of (PERM1, P < 0.001; SMYD1, P < 0.05). Swimming-induced enhancement in cardiac expression of PERM1 and SMYD1 was associated with a significant increase in ±dP/dt max (P < 0.05)). Conclusion: Expression of genes involved in cardiac metabolism can be affected by endurance training and this effect could be improved through MitoQ supplementatio

Lactate-induced autophagy activation: unraveling the therapeutic impact of high-intensity interval training on insulin resistance in type 2 diabetic rats

Abstract Impaired autophagy is a hallmark of diabetes. The current study proposed to investigate if high intensity interval training (HIIT) induced lactate accumulation could stimulate autophagy in type 2 diabetic male rats. 28 male Wistar rats were randomly assigned into four groups: Healthy Control (CO), Diabetes Control (T2D), Exercise (EX), and Diabetes + Exercise (T2D + EX). Diabetes was induced by feeding high-fat diet and administrating single dose of streptozotocin (35 mg/kg). After becoming diabetic, the animals in the exercise groups (EX and T2D + EX) performed an eight-week HIIT (4–10 interval, 80–100% Vmax, 5 days per week). Serum levels of lactate, glucose and insulin as well as the levels of lactate, pyruvate, lactate transporter monocarboxylate transporter 1 (MCT1), phosphorylated mitogen-activated protein kinases (p-MAP 1 and 2), phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ERK 1 and 2), mammalian target of rapamycin (p-mTOR), ribosomal protein S6 kinase beta-1 (p-70S6k), p90 ribosomal S6 kinases (p-90RSK), autophagy related 7 (ATG7), Beclin-1, microtubule-associated protein 1A/1B, and 2A/2B -light chain 3 levels (LC3-I), (LC3- II), (LC3I/LC3II) in soleus muscle were measured. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and serum glucose was lower in T2D + EX compared to T2D group (P < 0.0001). While serum and soleus muscle levels of lactate was not different between T2D and T2D + Ex, the levels of Pyruvate (P < 0.01), MCT1, p-ERK1/2, p-mTOR, p70S6k, P-90RSK, ATG7, LC3-II, and LC3-II/LC3I ratios were higher in T2D + EX compared to T2D group (P < 0.0001). We concluded that eight weeks of high-intensity interval training could activated ERK/P90SRK while inhibiting mTOR/P70S6K signaling pathway in lactate dependent manner. It means increased autophagy which resulted in improve insulin resistance (IR) and reduce blood glucose