Orthostatic Challenge After High-intensity Interval Exercise Vs. Continuous Aerobic Exercise In Young Women

Abstract

BACKGROUND: Orthostatic intolerance is one of the most common blood pressure regulation disorders and is highly prevalent and more common in young women. Young women tend to experience symptoms such as dizziness and fainting earlier and more often during the orthostatic stress. This tendency may be exacerbated after exercise when the phenomenon of post-exercise hypotension was superimposed. PURPOSE: This study aimed to investigate acute effects of two commonly performed exercises (high-intensity interval exercise and continuous aerobic exercise) on orthostatic responses after exercise in young women. METHODS: Twenty apparently healthy young women aged 18-35 years were studied. Assessment of peak oxygen consumption (VO2peak) was performed in the first visit. Each participant performed high-intensity interval exercise (HIIE) or continuous aerobic exercise (CAE) for 40 minutes each in a separate day. HIIE was performed at 80-90% of VO2peak (exercise:rest = 1:2). CAE was performed at 50-60% of VO2peak. Orthostatic challenge tests (i.e., rapid standing from the supine position) were performed before and at 0, 60, and 120 minutes after the exercise session was completed. RESULTS: Heart rate responses to the orthostatic stress were not different between the HIIE and CAE sessions. Both modes of exercise induced reductions in systolic blood pressure reductions after exercise. However, the magnitude of systolic blood pressure reduction during the orthostatic challenge was greater after the HIIE session (-13±6 mmHg) than the CAE session (-8±7 mmHg). CONCLUSION: These results suggest that compared with CAE, HIIE induced a greater reduction in systolic blood pressure during the orthostatic challenge and could make young women more prone to orthostatic intolerance.