The investigation of different menstrual cycle phase on muscle damage and oxidative stres markers

The aim of this study was to investigate the biomarkers of muscle damage, inflammation, oxidative stress and indirect markers of muscle damage following downhill running in the follicular (FP) and luteal phase (LP) (a) the time-dependent variation of the different phases, (b) the effect of phases on these changes, (c) the relationship between estrogen and the investigated biomarkers and indirect markers of muscle damage, and (d) the relationship between the investigated biomarkers. Thirteen sedentary and eumenorrheic (age: 20 ± 2.00 years; height: 163.81 ± 7.03 cm; menstrual cycle days: 27.93 ± 2.36 days; VO2max: 40.67 ± 4.69 mL.kg-1.min-1) woman were included in the study. Creatine kinase (CK), protein carbonyl (PCO) and lipid hydroperoxide (LHP) significantly increased over time (p<0.05), but total oxidized guanine (TOG) did not change over time (p>0.05). In addition, while there were no significant differences in CK, PCO, and LHP between the phases (p>0.05), TOG concentration was significantly different during the FP and LP (p<0.05). Myoglobin, interleukin-6, C-reactive protein, maximal voluntary isometric strength, active range of motion and active muscle pain perception values did not change over time (p>0.05), and were similar in both phases (p>0.05). There was a moderate positive relationship between estrogen and PCO in the FP (p<0.05), but there were no relationship between E2 and other investigated biomarkers (p>0.05). However, there was a significant relationship between change of muscle damage and oxidative stress (p<0.05). These results indicate that the oxidative stress plays a role in the muscle damage mechanism, but estrogen concentration does not relation with this process. Keywords: Muscle damage, Oxidative stress, Inflammation, Estrogen, Menstrual cycle