THE IMPACT OF RESISTANCE EXERCISE ON PERIPHERAL VASCULAR AND CEREBROVASCULAR FUNCTION IN RESISTANCE EXERCISE TRAINED AND UNTRAINED MIDDLE-AGED WOMEN

Abstract

In middle-age, women experience an increased risk for hypertension and resultant vascular dementia, partially due to concomitant aging and the loss of endogenous estrogen production with menopause. Vascular dysfunction, arterial stiffening, and cerebrovascular dysfunction contribute to heightened hypertension and vascular dementia risk. Aging and menopause concurrently increase the risk for these aberrant physiologies while exercise dampens the risk. More specifically, resistance exercise training (RET) improves vascular health, particularly in aging women, making RET critical in the context of hypertension and vascular dementia. The vascular health benefits of RET stem from adaptations to large oscillations in blood pressure and blood flow experienced during acute resistance exercise (RE). Further, an acute hypertensive challenge, such as acute RE, is a systemic physiological stressor that can be utilized to understand the cardiovascular implications of inactivity or long-term RET engagement. However, there are limited studies investigating vascular health, RET, and acute RE in middle-aged women. In young women, RET preserves carotid artery compliance and central arterial stiffness while also improving peripheral vascular function responses to an acute hypertensive stimulus (acute RE). However, the effect of RET on cerebrovascular function is largely uncharacterized, particularly in women. Taken together, understanding the effect of acute RE and RET on central and carotid artery stiffness, peripheral vascular function, and cerebrovascular function in middle-aged women is critical yet largely understudied. Therefore, the aims of the present dissertation were (1) to investigate the effects of an acute hypertensive stimulus (acute RE) on aortic and carotid artery stiffness, macrovascular and microvascular function, and cerebrovascular function in untrained and long-term resistance-trained middle-aged women, (2) to assess the effect of 8-week RET on resting and post-hypertensive stimulus (acute RE) vascular function in initially untrained middle-aged women, and (3) to compare the efficacy of 8-week RET versus long-term RET in the context of vascular responses to an acute hypertensive stimulus in middle-aged women. The present dissertation included gold-standard measurements (blood pressure, flow-mediated dilation, pulse wave velocity) and critical, understudied measurements (carotid artery wave reflection, middle cerebral artery velocity, and cerebrovascular reactivity). It was hypothesized long-term resistance-trained middle-aged women would exhibit beneficial arterial stiffness and vascular function responses to acute RE, as indicated by preserved aortic and carotid artery stiffness, improved or preserved peripheral vascular function, preserved cerebral blood velocity, and increased cerebrovascular reactivity. It was also hypothesized initially untrained middle-aged women would exhibit deleterious responses to acute RE (elevated aortic and carotid artery stiffness, impaired peripheral vascular function, impaired cerebral blood velocity and cerebrovascular reactivity), and post-acute RE responses would improve after 8-week RET. The overall conclusions are (1) long-term RET does not negatively impact central aortic stiffness and confers positive macrovascular, microvascular, and cerebrovascular responses to acute RE in middle-aged women, (2) 8-week RET induces beneficial macrovascular responses to acute RE in middle-aged women, and (3) in middle-aged women, 8-week RET confers similarly beneficial vascular responses to acute RE when compared to long-term RET.