Examining the Circadian Timing Effects of the Hypotensive Response to Exercise

Overview

The goal of this study is to learn how exercise timing affects blood pressure in adults with elevated or high blood pressure. Exercise can influence the body's natural 24-hour rhythms, including blood pressure patterns. A single exercise session can lower blood pressure for up to 24 hours, but it is not fully understood how the time-of-day for exercise affects this response. The main question this study aims to answer is: • When the same participant exercises at different times of day (morning, afternoon, or evening), how does this affect the participant's blood pressure over the next 24 hours? Participants will: * Undergo an in-lab assessment of individual biological rhythm that will indicate the clock-time for an individual's biological night * Complete 3 supervised treadmill exercise sessions * 1 in the biological morning (biological night + 10 hours) * 1 in the biological afternoon (biological night + 15 hours) * 1 in the biological evening (biological night + 20 hours) * Complete a 24-hour blood pressure assessment before and after each exercise session

This fully counterbalanced, within-subject, randomized crossover trial will examine the time-of-day dependent hypotensive effect of exercise in adults aged 18-39 years with elevated blood pressure or stage 1 hypertension. To examine this, participants will complete an assessment of dim-light melatonin onset (DLMO), the gold standard assessment of individual circadian phase, which will be used to subsequently prescribe three exercise sessions in the morning (10 hours after DLMO), afternoon (15 hours after DLMO), and evening (20 hours after DLMO) with 24-hour blood pressure assessment before and after each exercise sessions.