Central Hemodynamic Exercise Responses Study (CHeER)

The specific aim of this study is to compare postexercise central blood pressure after continuous and aerobic interval exercise. It is hypothesized that aerobic interval exercise will produce a longer duration postexercise hypotensive response compared to continuous exercise. 14 healthy, inactive (defined as less than 60 minutes of moderate to vigorous physical activity per week, as characterized by accelerometry) men aged 18-45 yr, who have high normal BP or stage 1 hypertension (systolic BP (SBP) 120-159 mmHg or diastolic BP (DBP) 80-99 mmHg) according to JNC 8 established guidelines, will be included in this randomized cross-over design study. Each subject will complete three conditions in a randomized order: aerobic interval exercise, continuous exercise, and non-exercise control.

For the aerobic interval exercise condition, subjects will be equipped with a heart rate (HR) monitor and asked to perform an interval exercise bout on a cycle ergometer. To warm up, subjects will cycle at a work rate associated with 50% HRmax for 10 minutes. Wattage will then increase and subjects will do four 4-minute intervals at a work rate associated with 90%-95% HRmax, separated by 3 minutes of active recovery at a work rate associated with 50% HRmax. Subjects will be given a 5-minute cool-down period at a work rate associated with 50% HRmax. After the exercise, subjects will remain in the lab for 4 hours and their blood pressure will be measured every 10 minutes using the Oscar 2 with SphygmoCor ambulatory blood pressure system, and cardiac output measured in 10-second averages using the PhysioFlow. During this time, subjects will remain seated with their body posture maintained constant.

For the continuous exercise condition, subjects will be equipped with a HR monitor and asked to perform a continuous exercise bout on a cycle ergometer. To warm up, subjects will cycle at a work rate associated with 50% HRmax for 10 minutes. Wattage will then increase and subjects will perform a 30-minute exercise bout at a HR that elicits 75%-80% of their measured HRmax. Work rate will be adjusted, if needed, to keep HR within this value. Subjects will be given a 5-minute cool-down period at a work rate associated with 50% HRmax. After the exercise, subjects will remain in the lab for 4 hours and their blood pressure will be measured every 10 minutes using the Oscar 2 with SphygmoCor ambulatory blood pressure system, and cardiac output measured in 10-second averages using the PhysioFlow. During this time, subjects will remain seated with their body posture maintained constant.

For the non-exercise control condition, subjects will be asked to come to the laboratory for 4 hours and have their blood pressure will be measured every 10 minutes using the Oscar 2 with SphygmoCor ambulatory blood pressure system, and cardiac output measured in 10-second averages using the PhysioFlow. During this time, subjects will remain seated with their body posture maintained constant.