Year of Award

2024

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Integrative Physiology and Rehabilitation Sciences

Department or School/College

Department of Integrative Physiology and Athletic Training

Committee Chair

Charles Dumke

Commitee Members

John Quindry, Reed Humphrey, James Laskin, Erin Semmens

Keywords

breast cancer, cardiovascular health, estrogen, menopause, menstrual cycle, progesterone

Abstract

The overall aim of this dissertation was to investigate the influence of female sex hormones on the response to exercise in premenopausal and postmenopausal women. Study one examined the effect of menstrual cycle phase on thermoregulation during prolonged exercise in the heat. Notably, elevated core temperature and basal aldosterone was apparent in the mid-luteal phase corresponding with elevations in estrogen and progesterone. Aldosterone significantly increased following exercise in the heat but remained elevated in the mid-luteal phase, suggesting a previously unexplored menstrual phase-aldosterone hormonal additivity under the stress of uncompensable heat. Study two was a survey-based investigation with the aim of understanding physical activity (PA) patterns of breast cancer (BC) survivors in western Montana. Data from 50 survivors show that PA, represented as minutes of activity per week, significantly increased following diagnosis, largely via resistance training. The largest improvements in PA were seen in those who had the lowest starting PA levels, and exceed national trends, indicating the efficacy of community-based programs and exercise perspectives to promote exercise adherence. Study three assessed the influence of a quickly growing exercise modality for BC survivors, Dragonboat racing, on physiological markers of health across a 16-week season. Notably, study three found that seasonal Dragonboat training can maintain aerobic capacity in an already fit group of survivors and improve cardiovascular risk factors like blood pressure and visceral adiposity. Dragonboat training appears to be a sufficient stimulus to maintain and improve bone mineral density in a postmenopausal survivor group. Further, seasonal paddling can redistribute visceral body fat and improve fasting metabolic status without corresponding changes in serum estradiol or progesterone like traditional modalities, providing support that Dragonboat training can provide a beneficial exercise program in BC survivors. Study four compared the vascular response to exercise in postmenopausal women with and without a history of breast cancer chemotherapy. This study found that indicate that despite BC treatment history and reduced estrogen, postmenopausal BC survivors retain a healthy vascular and metabolic response to acute aerobic exercise comparable to healthy postmenopausal control women. Blood pressure appears to be an important mediator of vasodilatory capacity after exercise, highlighting the need for long-term cardiovascular monitoring in both breast cancer survivors and healthy postmenopausal women. Collectively, work from this dissertation provides valuable research on the influence of female sex hormones on exercise in women, during both pre- and post-menopause, and in BC where estrogen and progesterone play important roles in tumor growth and treatment options.

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© Copyright 2024 Katherine Sue Christison