جستجوی مقالات مرتبط با کلیدواژه « انقباض اکسنتریک » در نشریات گروه « زیست شناسی »

The purpose of this study was to evaluate the response of mTOR/P70S6K myokines to eccentric and concentric physical activity in healthy young men. 10 healthy men were randomly divided into each group (concentric group of 5 people - eccentric group of 5 people). Isokinetic contraction protocols included eccentric and concentric knee extensions with a maximum strength and angular velocity of 60 °/s. The torques set for each subject were considered the same in order to match the load in both protocols and the reciprocating speed was 60 degrees per second. At the beginning and end of the study, a biopsy was performed of lateral extensor muscle tissue. Real Time PCR technique was used to evaluate the expression of mTOR/P70S6K gene. To analyze the data of this study, dependent t-test and analysis of covariance were used at a significance level of 0.05. The results showed that the changes within the mTOR group were significant in the concentric group but not significant in the eccentric group. Also, the intragroup changes of P70S6K in the eccentric and concentric groups were not significant (P≥0.05). Also, intergroup changes showed no difference between the two groups in both variables (P≥0.05). It seems that the lack of significant changes in the desired variables is due to the lack of sufficient training pressure to stimulate the increase of mTOR/P70S6K. And according to the review of the answer, it seems that in the discussion of compatibility, different results are obtained that need to be examined.

This study was mainly aimed at investigating gene expression of MyF5 and MyoG genes of eccentric and concentric resistance activity in the vastus lateralis muscle of healthy individuals. Ten healthy men were randomly assigned to two groups of concentric and eccentric contractions of five. Isokinetic contraction protocols included eccentric and concentric knee extension with a maximum power and angular velocity of 60 degrees per second. The torque set for each subject was considered the same in both protocols in order to match the load, and the reciprocating speed was 60 degrees per second. At the beginning and end of the activity, extensive biopsy was performed to examine the expression of MyF5 and MyoG genes. Results revealed that intra-group changes of MyF5 after one session of exercise were significant in eccentric (p = 0.001) and non-significant in concentric (p = 0.069) group. Moreover, inter-group changes showed no difference between the two group (p = 0.371). Besides, intra-group MyoG changes after one session of exercise were significant in the eccentric group (p = 0.001) and concentric group (p = 0.001). Furthermore, inter-group changes showed no difference between the two groups (p = 0.681). Overall, the present study showed that a session of eccentric and concentric activity leads to changes in the factors involved in skeletal muscle strength and hypertrophy. In addition, these changes in aggregate eccentric contraction are more than concentric.
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The present study aimed to investigate the response of MyoD and MRF4 myokines to eccentric and concentric activity in healthy young men. Ten healthy males were split into two groups of five, each with concentric and eccentric contractions. Excentric and concentric knee extension with a maximal power and angular velocity of 60 per second were used in isokinetic contraction protocols. The torque set for each subject was considered the same in both protocols to match the load, and the reciprocating speed was 60 degrees per second. At the beginning and end of the activity, the extensive biopsy was performed to examine the expression of the MyoD and MRF4 genes. The results showed that the intragroup changes of MRF4 after one session of activity were not significant in the eccentric (p = 0.229) and concentric (p = 0.178) groups. Furthermore, intergroup changes showed no difference between two groups (p = 0.182). Moreover, the changes within MyoD group after one activity session were significant in the eccentric group (p = 0.001) but not significant in the concentric group (p = 0.318). Moreover, intergroup changes showed no difference between the two groups (p = 0.821). In general, the present study showed that one session of eccentric and concentric activity leads to changes in the factors involved in skeletal muscle strength and hypertrophy. Besides, these changes were generally greater in the eccentric than concentric contraction. Therefore, it is recommended to focus more on concentric exercises to increase hypertrophy and muscle strength.

Skeletal muscle resorption is caused by the biosynthesis of new structures involved in the muscle contraction in terms of the increased skeletal muscle cross-sectional area, which is recognized as one of the major muscle changes as a result of exercise. This study aimed to investigate the response of mTOR and AKT proteins to distinct eccentric and concentric resistance training in healthy subjects. Ten healthy men were randomly divided into two groups (5 patients in the eccentric group - 5 in eccentric group). Isokinetic contraction protocols included eccentric and concentric knee extension with maximum power and angular velocity of 60 degrees per second. The torques assigned to each subject were assumed to match the workload in both protocols, with a rotational speed of 60 degrees per second. Contractions consisted of a maximum of 12 sets of 10 repetitions for the right leg, a rest time of 30 seconds between each set. At the beginning and end of the study, biopsy of the lateral broad muscle tissue was performed. A biopsy was performed in both distal and proximal directions of lateral flat muscle. Tissue analysis using immunocytochemistry was used to assess the expression of mTOR and AKT proteins in each group. A dependent t-test and a covariance test were used to assess the data. For data analysis, SPSS21 and Exell 2013 software were utilized. The findings indicated that after one session of exercise, intra-group increases in mTOR and AKT proteins were significant in both eccentric and concentric groups (p ≤0.05).However, the inter-group changes of mTOR and AKT proteins showed no difference between two groups. In general, the present study showed that a session of eccentric and concentric activity leads to changes in the factors involved in skeletal muscle strength and hypertrophy. Besides, these changes in aggregate eccentric contraction are more than concentric.