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Exercise;Hormones;Immune;Menstrual cycle


Kevin Milne



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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


High-intensity exercise increases inflammation and elicits leukocytosis but may also increase infection risk. Interestingly, females have higher cell-mediated immunity than males. Estrogen fluctuates across the menstrual cycle, and the luteal phase has been linked to a more pro-inflammatory environment than the follicular phase. This study aimed to identify whether white blood cell (WBC) count and differentiation (i.e., neutrophils, lymphocytes, monocytes, eosinophils and basophils), and inflammatory markers (i.e., GM-CSF, IFN-��, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-��, and TGF-��) differed across two menstrual cycle phases following an acute bout of exercise. Eight regularly menstruating female adults completed a ��O2peak test and two 40-minute cycling exercise trials (30-mins of moderate intensity and 10-mins of high intensity) 14 days apart. Blood samples were taken pre-, post moderate intensity exercise (30min), and immediately post vigorous intensity exercise (~40min). Both moderate- and high-intensity exercise led to an increase in WBC counts. More specifically, neutrophils were increased following both exercise intensities, while lymphocytes and monocytes were only elevated following high intensity exercise. Menstrual cycle phase did not significantly alter WBC counts or differentials although there were trends towards greater leukocytosis at moderate intensity exercise during the luteal phase. IFN-�� demonstrated a significant effect between menstrual cycle and exercise intensity. Moreover, TGF-��, as measured by ELISA, tended to be greater during the follicular phase. These results demonstrate that acute bouts of high-intensity exercise increased total WBC counts (i.e., neutrophil, monocyte, and lymphocyte expression) and supports the phenomenon of exercise-induced leukocytosis. Future research should investigate this relationship in a larger sample observing pro- and anti-inflammatory cytokines and WBC function/activity with the inclusion of a group in the early follicular phase.

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