Exercise-Induced Inflammation during Different Phases of the Menstrual Cycle

Objective: To examine the effects of menstrual cycle on exercise-induced inflammation, we investigated exercise-induced changes in circulating cytokines and leukocyte responses during different phases of the menstrual cycle. Methods: Ten healthy sedentary females (20.5 ± 0.7 years) performed 60 min of cycling at 75% of their individual anaerobic threshold (AT) during the three different phases of the menstrual cycle (menstrual, follicular and luteal phases). Blood and saliva were sampled baseline, post- and 30 min post-exercise. The salivary concentrations of female sex hormones, progesterone and 17β-estradiol, and plasma concentrations of pro-inflammatory cytokines, interleukin (IL)-6 and IL-8, and markers of leukocyte activation, calprotectin and myeloperoxidase, were measured in all the blood and saliva sampling intervals. Results: The plasma concentration of IL-6 increased significantly post-exercise (p<0.001) and the plasma concentration of calprotectin increased significantly 30 min post-exercise (p<0.05) in all the three menstrual cycle phases. A positive correlation was found between exercise-induced changes in plasma IL-6 and calprotectin concentrations in the menstrual phase, suggesting the possibility of enhanced leukocyte reactivity to IL-6 during this phase. Conclusion: These findings suggest that 60 min of strenuous exercise at an intensity of higher than 75% AT may induce inflammation in sedentary females, especially during the menstrual phase of the menstrual cycle.