Date of Graduation

5-2016

Document Type

Thesis

Degree Name

Master of Science in Kinesiology (MS)

Degree Level

Graduate

Department

Health, Human Performance and Recreation

Advisor/Mentor

Ganio, Matthew S.

Committee Member

Gray, Michelle

Second Committee Member

Kavouras, Stavros A.

Keywords

Health and environmental sciences; Arterial stiffness; Passive heating; Thermoregulation

Abstract

Context: Cardiovascular disease (CVD) is one of the leading causes of mortality in the United States, accounting for about 1 in every 4 deaths annually. Studies have shown that passive heating does have some degree of effect on arterial stiffness, but not much is known about populations with higher stiffness. Objective: To examine the independent effect of core temperature increase during passive heating on arterial stiffness. Methods: Participants visited the lab three times; one familiarization and two experimental trials. The experimental trials consisted of subjects being passively heated in an environment of 40°C / 40% relative humidity (HEAT) or normal laboratory conditions (CONTROL). Participants were 48.9 ± 12.0 years old of age, 66.7± 12.6 kg, 168.2 ±8.8 cm, and 7.7 ± 2.0 m/s central pulse wave velocity. Main Outcome Measures: Before and after passive heating, pulse wave velocity (PWV measures occurred via ultrasound at the tibial, radial, femoral and carotid artery sites). At the same time, rectal temperature (Trec) was measured. Trec was measured with rectal thermistors; differences between trials confirm the changes that occurred as a result of environmental conditions. Central arterial stiffness was assessed by using measures between the carotid and femoral artery sites, while peripheral stiffness was assessed using the radial and tibial artery sites. The radial site was used for upper peripheral arterial stiffness and the tibial site was used for lower peripheral arterial stiffness. Results: Trec at the end of passive heating showed significant differences between the CONTROL and PASSIVE HEAT trials respectively (36.53 ± .16 vs. 38.14 ± .49°C; p < 0.001). There were no interactions (p>0.05) between time and condition for central pulse wave velocity (∆ 1.83 ± 50.44 vs. 3.25 ± 67.34 cm/s; for control and passive heating respectively), upper peripheral (∆ 51.50 ± 60.87 vs. 92.77 ± 82.81 cm/s), and lower peripheral pulse wave velocities (∆ 46.99 ± 68.55 vs. 23.70 ± 156.67 cm/s). Conclusions: The findings of this study indicate that differences in mean body temperature do not result in significant decreases in arterial stiffness following passive heating in individuals with poor arterial stiffness at baseline.

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