Hassan Kosari; Pezhman Motamedi; Hamid Rajabi; Shahriar Gharibzade; Shapour Jaberzadeh
Abstract
Background and Aim: Changes in corticospinal excitability will cause a change in the neural output and finally the maximum force will be changed. Various training and non-training factors affect this neuromuscular response and it seems that the intensity of the intervention is one of the effective factors ...
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Background and Aim: Changes in corticospinal excitability will cause a change in the neural output and finally the maximum force will be changed. Various training and non-training factors affect this neuromuscular response and it seems that the intensity of the intervention is one of the effective factors in this regard. Based on this, the present study sought to investigate the response of corticospinal excitability to different intensities of postactivation potentiation in young trained subjects. Materials and Methods: Eight young men (24.8±2.70 year) performed the research protocol in three separate sessions with preparatory contractions during the handgrip movement with intensities of 20, 50 and 80% root mean square of maximal voluntary contraction. Several times after that, the amount of corticospinal excitability, the electrical activity of the flexor carpi radialis muscle (FCR) and the maximum force in the hangrip were measured with a dynamometer. Then, the results were extracted by using the statistical method of repeated-measures analysis of variance at a significance level of p<0.05. Results: The amplitude of motor evoked potential increased after preparatory contraction with intensity of 20%, but it decreased significantly after intensity of 50% and 80%; so that, there was no significant difference between the intensity of 50% and 80%. On the other hand, the amount of voluntary force measured by the maximum voluntary contraction did not show any significant change as well as the electrical activity immediately and after 5 minutes of preparatory contraction. Conclusion: None of the changes in corticospinal excitability were associated with changes in muscle strength and electrical activity. Therefore, there is a complex interaction between changes in supraspinal excitability following preparatory contractions and their effect on an individual’s ability to improve or maintain force output, and further investigations are needed in this area.
Reza Moqimi; Hamid Rajabi; Sadegh Sadegh Amani-Shalamzari
Abstract
Background and Aim: Resistance training with blood flow restriction stimulates the response and release of anabolic hormones and increases hypertrophy in restricted muscles, however, the effect of this training method on adjacent non-restricted muscles has not been studied well. The aim of this study ...
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Background and Aim: Resistance training with blood flow restriction stimulates the response and release of anabolic hormones and increases hypertrophy in restricted muscles, however, the effect of this training method on adjacent non-restricted muscles has not been studied well. The aim of this study was to evaluate the effect of 4 weeks of resistance training along with blood flow restriction on anatomical cross-sectional area (CSA) of adjacent non-restricted muscles in active young men. Materials and Methods: Sixteen young men aged 25-30 years old were randomly divided into two groups (n=8) high-intensity resistance training (HIRT) and low-intensity resistance training with blood flow restriction (L-BFR). Both groups performed bench press and squat exercises three sessions per week during four weeks. In HIRT group, three sets of 10 repetitions (75%1RM), and in the L-BFR, four sets of 30, 15, 15 and 15 repetitions (30%1RM) was performed during every exercise. For L-BFR group, the restriction pressure was considered as 50% resting atrial occlusion pressure (AOP) at the beginning of the exercises and this pressure gradually was increased to 80% AOP during four weeks. At the beginning and 72 hours after the last training session, the CSA of triceps brachii, pectoralis major, quadriceps and gluteus maximus were calculated by MRI. Data were analyzed by paired sample t-test and analysis of covariance (ANCOVA) test at the significance level of p<0.05. Results: Four weeks of training lead to significant increase in the cross-sectional area of triceps brachii, quadriceps, pectoralis major and gluteus maximus in the HIRT (4%, 7.5%, 10%, 10% respectively) and L-BFR (11%, 12%, 18%, 22% respectively) groups. Conclusion: It seems that the anabolic effects caused by blood flow restriction exercises are not limited locally and can be transferred to the adjacent muscles involved in the exercise that are not directly affected by the blood flow restriction.
Hamidreza Barzegarpoor; Hamid Rajabi; Duen Button; Rana Fayazmilani
Abstract
Background and Aim: It seems that the combination of brain endurance training and physical endurance training can increases endurance exercise performance throughout reducing rating of perceived exertion more than solely physical endurance training. The aim of this research was to study the effect of ...
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Background and Aim: It seems that the combination of brain endurance training and physical endurance training can increases endurance exercise performance throughout reducing rating of perceived exertion more than solely physical endurance training. The aim of this research was to study the effect of physical endurance training, and brain endurance training on fatigue and exercise tolerance in active people. Materials and Methods: 20 healthy volunteers (14 men and 6 women) were assigned into two groups as: physical endurance training + brain endurance training and physical endurance training. Both groups trained on a cycle ergometer for 60 minutes at 60-75 heart rate reserve. Whilst cycling, the brain endurance training group performed a mental exertion on a computer. Both groups trained 3-4 times a week for 24 sessions. Maximal oxygen consumption during an incremental test and exercise tolerance with constant load exhausting test were measured at pre and post training. Rating of perceived exertion and heart rate were recorded every two minutes during time to exhaustion test. Data were analyzed using mixed model analyze of variance and significant level was set as p˂0.05. Results: Maximal oxygen consumption increased in both groups (p=0.01); however, for time to exhaustion variable it showed more increasing in the brain endurance training and physical endurance training group than in the physical endurance training group (p=0.01). Brain endurance training and physical endurance training group compared to the physical endurance training group indicated significantly reduction on the rating of perceived exertion during time to exhaustion test (p=0.01). Conclusion: The results of this study provide evidence that the combination of the brain endurance training and physical endurance training than physical endurance training can increased more endurance exercise performance throughout decrease rating of perceived exertion.
Mohsen Mohammadnia Ahmadi; Hamid Rajabi
Abstract
Background and Aim: Nowadays, cold-water immersion (CWI) has been established as a promising means to support recovery in high performance sports after highly intensive training bouts or competitions. There are many studies about effectiveness of acute CWI to support recovery after strenuous exercise, ...
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Background and Aim: Nowadays, cold-water immersion (CWI) has been established as a promising means to support recovery in high performance sports after highly intensive training bouts or competitions. There are many studies about effectiveness of acute CWI to support recovery after strenuous exercise, but the overall results seem to be conflicting. However, adaptational aspect has been widely neglected. Therefore, we analyzed the effects of immersion in cold and moderate water after resistance training on the some adaptations of strength training. Materials and Methods: In all, 32 male Sprague-Dawley rats (8-weeks) were assigned randomly into 4 equal groups including control (208.50±22.50 g), resistance training (208.87±26.70 g), resistance training + moderate water immersion (208.37±16.30 g.) and resistance training + cold water immersion (218.75±33.20 g) groups. The resistance training consisted of climbing (5 reps/3 sets) a ladder (120 cm) carrying load (equal to a percent of body weight) suspended from the tail. At last set (during 6 minute), rats in immersion water groups, immersed within container consisted water with 27˚C and 14˚C respectively. This process repeated 3 times a day during 8 weeks. At the first and last session, ladder climbing strength maximal was measured. Immediately after euthanasia (24 h after final training session), the flexor hallucis longus (FHL) and soleus muscles and subcutaneous-inguinal fat tissue was exposed and weighed. The data was analyzed with the one-way ANOWA method and significance level considered if pResults: Results showed that subcutaneous-inguinal fat (p=0.01), FHL and soleus weight (p=0.01) and maximal strength of ladder climbing (p=0.001) were significantly different in all studied group; so the best improvement was obvious at the resistance + moderate water immersion group. Conclusion: It is concluded that immersion in moderate water have a better impact on the strength training adaptations in rats.
