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Background: Delayed muscle soreness occurs after resistance activity or training involving an eccentric component, and nutrition can affect the extent of muscle injury by playing a role in both protein synthesis and catabolism. The objective of this study was to evaluate the effect of using glutamine supplementation in 3 days on injury indices after a session of eccentric resistance exercise
Methods: In a double-blind study, 20 voluntary non-athlete male subjects [age 21.1 ± 2.3 yr., height 177 ± 3 cm, weight 77.1 ± 6.2 kg, Body Mass Index (BMI) 24 ± 1.9 kg/m2, body fat 14.8 ± 4.5%] were divided randomly into 2 groups with 10 member supplement (glutamine) and placebo (maltodextrin). Serum creatine kinase was measured by photometric method and muscle pain was determined by using a standard scale of PAS in 24, 48 and 72 hours after resistance test which involved leg press.
Results: Three subsequent days of using glutamine amino acid did not demonstrate significant difference in decreasing injury indices after eccentric leg press (p>0.05).
Conclusion: It seems that this dose of supplement is not sufficient in regard to the number of days administered and in order to show the positive effects of amino acid, it should be used for more number of the days. So, to clarify the effects of glutamine supplement, there is need to conduct further studies with more accurate control and more data collection times.

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Background: The efficacy of glutamine and Curcumin consumption and their synergistic effect on muscle damage recovery over five days is not clear yet. The purpose of this study was to compare the effect of these two supplements and their synergistic effect on serum markers of muscle damage and muscular pain perception after an eccentric exercise session.
Methods: Forty non-athlete young men were randomly divided into four groups. Each group received a supplement or placebo for five days, group 1: glutamine [Gln 0.1 gr⁄(Kg/day)], group 2: curcumin (Cur 1000  mg/day), Group 3: glutamine [Gln 0.1 gr⁄(Kg/day)] + curcumin (Cur 1000  mg/day) and group 4: maltodextrin [Pla 0.1  gr⁄(Kg/day)] as placebo. The last supplement was taken 8 hours before eccentric exercise. Measurements were taken before the resistance exercise and, 24 and 48 hours after. Serum Creatine Kinase (CK) and Lactate Dehydrogenase (LDH) were measured using photometric method and muscle pain measured using standard pain scale. The resistance exercise included leg press with 70% of 1RM.
Results: There was a significant decrease in serum CK and LDH and muscle soreness in curcumin group and glutamine + curcumin group compared to the placebo group at all times (P<0.05). There was no significant difference in glutamine group compared to the placebo group, and glutamine + curcumin group had no significant difference compared to the curcumin group.
Conclusion: According to the results of this study, it seems that consumption of curcumin for five days can decrease some of the indices of muscle damage and also muscle pain after an eccentric exercise, but consumption of glutamine along with curcumin had no significant effect on muscle damage indices compared to the curcumin only. Therefore, these nutrients have no synergistic effect.

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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.