Effects of eccentric exercise induced delayed onset muscle soreness on some endoplasmic reticulum stress parameters in athletes

The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) is defined as ER stress and it has been shown that muscle damage caused by repeated eccentric exercises have provoked ER stress in the skeletal muscles. Muscle damage and delayed onset muscle soreness (DOMS) are known to negatively affect athlete performance. The aim of the study was to investigate the effect of eccentric exercise induced DOMS on ER stress parameters in young athletes. Eighteen young male football players participated in the study voluntarily. A muscle damage protocol with eccentric contractions with an isokinetic dynamometer was used for participants. Apelin, interleukin 6 (IL6), Pentraxin 3 (PTX3) and as muscle damage markers creatine kinase (CK) and lactate dehydrogenase (LDH) enzyme levels were assessed in totally 5 times from blood samples as baseline, immediately after, 24, 48 and 72 hours after the exercise protocol. In addition, maximal strength test and rate of perceived exertion using visual analogue scale (GAS) were applied to participants in the same order after blood collection. The Friedman F test was used to compare repeated measures for statistical analysis, Wilcoxon signed rank test to determine which measure the statistical difference originated from, analysis of variance in repeated measures for force data, and the Bonferroni post hoc procedure was used to analyze which group the difference originated from for only maximal strength data. Spearman correlation test was used to determine the significant relationship. Statistical significance was set at the 0.05 level of confidence. There were significant differences between baseline and first post-test of exercise protocol for IL6, CK, LDH levels and strength test, and GAS; and between repeated measures for all parameters except PTX3 (p<0.05). PTX3, IL6, CK levels reached peak at 24 h after exercise, while LDH level reached it's peak at 48h. Increases in apelin, IL6 and PTX3 levels following muscle damage protocol may have resulted in ER stress formation; increases in CK, LDH, GAS and decrease in strength levels seem to provide existence of DOMS. Key words: Apelin, creatine kinase, eccentric exercise, interleukin6, muscle damage, Pentraxin 3