effects of eccentric and concentric emphasized resistance exercise on il-15 serum levels and its relation to inflammatory markers in athletes and non-athletes

Background: cytokines play an important role in modulating the muscle’s metabolic and immunological responses to exercise. objectives: in the present study, we investigated changes in the serum levels of interleukin (il)-15 as well as tumor necrosis factor (tnf)-α and high sensitivity c-reactive protein (hs-crp), as markers of inflammation, in athlete and non-athlete young men following eccentric (ecc) and concentric (con) emphasized resistance exercise (re). patients and methods: this study recruited 28 young males, 14 athletes and 14 non-athletes. subjects completed two bouts of ecc and con emphasized re five days apart. each bout included seven exercises that emphasized all major muscle groups with weight loads of 70% - 80% of one repetition maximum (1rm) for con re and 90% - 100% of 1rm for ecc re. we analyzed subjects’ blood samples before and immediately after each bout of exercise to determine cytokine and hs-crp serum levels according to enzyme-linked immunosorbent assay. results: statistical analysis showed a significant difference between il-15 serum levels before and after ecc and con re in non-athletes (p = 0.03). in athletes, il-15 serum level only increased after ecc re (p = 0.01), which was noted to be the highest degree of change in il-15 levels in all subjects. for athletes, the hs-crp levels significantly decreased (p < 0.05). the serum levels of both tnf-α and hs-crp were also significantly down-regulated after ecc re in non-athletes. conclusions: these results indicated that fitness level and re could modulate circulating levels of il-15 and suggest the potential anti- inflammatory effects of il-15 during re.