TrKB and FNDC5 Gene Expression and SG6K1 Protein Response to Eccentric and Concentric Resistance Activity in Young Men

Background: The aim of the present study was to investigate the expression of TrKB, FNDC5 and SG6K1 protein in response to eccentric and concentric resistance training in healthy subjects. Methods: 10 healthy men were randomly assigned to two groups of concentric and eccentric contractions of 5 individuals each. Isokinetic contraction protocols included eccentric and concentric knee extension with a maximum power and angular velocity of 60 degree/sec. The torque set for each subject was considered the same in both protocols; 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 the TrKB and FNDC5 genes and the amount of SG6K1 protein. Results: The results showed that intra-group changes of TrKB and FNDC5 were not significant in eccentric and concentric groups (p≥0.05). Also, intra-group changes of SG6K1 protein after one session of activity were significant in eccentric and concentric groups (p≤0.05). However, no significant difference was observed between groups in the post-test in any of the variables (p≥0.05). Conclusion: 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. Therefore, it is recommended to focus more on concentric exercises to increase hypertrophy and muscle strength.