Passive Heat Therapy for Lowering Systolic Blood Pressure and Improving Vascular Function in Mid-life and Older Adults

36 sessions (\~3x per week for 12 weeks) of hot water immersion in 40°C water, sufficient to raise body core temperature to 38.5°C, and 12 weeks of follow-up.

36 sessions (\~3x per week for 12 weeks) of thermoneutral water immersion in 36°C water to prevent changes in body core temperature \>0.2°C, and 12 weeks of follow-up.