Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Health, Sport and Exercise Science (PhD)

Degree Level

Graduate

Department

Health, Human Performance and Recreation

Advisor/Mentor

Ganio, Matthew S.

Committee Member

Turner, Ronna C.

Second Committee Member

Howie, Erin K.

Third Committee Member

Gallagher, Kaitlin M.

Keywords

cardiovascular; health; physiology; vascular dysfunction; arterial angulations

Abstract

Purpose: The purpose of these studies was to determine if arterial angulations (through sitting or standing), shear stress (through local heating), or a combination of these factors affected vascular function. Moreover, this studied estimated the magnitude of the effect that biological sex has on these vascular responses. Methods: Twenty-six healthy, young (18-40 years old) males (n=13) and females (n=13) completed two experimental trials (2-h sitting and 2-h standing). In a randomized fashion, one leg was passively heated in order to increase shear rate. Following a 48-h washout, participants returned to the laboratory to complete the other trial. Flow-mediated dilation (FMD) at the superficial femoral artery (SFA), and central and peripheral pulse-wave velocity (PWV) were measured using vascular ultrasound. Endothelin-1 (ET-1) was analyzed using an enzyme-linked immunoassay (ELISA). Results: There was a non-significant decrease in FMD (1.45%; p = .06) during sitting and the decline in FMD was not different between biological sexes (p > .05). Further, standing resulted in a significant increase in peripheral PWV (50 cm/s; p < .05) but there was no change during sitting (p > .05). Overall, passive heating (1.42%; p < .05) and standing (1.42%; p < .05) both independently improved FMD in comparison to sitting. However, neither intervention attenuated the increases in peripheral PWV that occurred during standing (p > .05). ET-1 did not increase over the course of either trial and was not different between sexes (p > .05). Antegrade shear rate increased (p < .001) and retrograde stress decreased (p < .001) when passively heated. Further, there was vasoconstriction during standing with SFA diameter decreasing compared to sitting (0.28 mm; p < .001). Conclusions: Both interventions, passive heating and standing, appear to be equally effective at improving FMD. Further, we demonstrate that there is no significant impact of biological sex on sitting induced vascular dysfunction and the interventions intended to prevent this dysfunction. However, standing increased peripheral PWV and passive heating did not attenuate this response.

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