Acute Effect of High-Intensity Interval Exercise on Blood Pressure in Females Living with Type 2 Diabetes and Hypertension.

Background : The acute effects of high-intensity interval training (HIIT) on blood pressure (BP) may depend on the exercise protocol performed. Purpose: To compare the acute effect of high and low-volume HIIT on post-exercise and ambulatory BP in untrained older females diagnosed with both type 2 diabetes (T2D) and hypertension (HTN). Methods: Fifteen females (69 [65 ─ 74] years) completed a crossover study with three experimental conditions: 1) REST (35 min in sitting position); 2) HIIT10 (10 × 1 min at 90% heart rate max [HRmax]), and 3) HIIT4 (4 × 4 min at 90% HRmax). After each experimental condition, BP was measured under controlled (4 hours) and in subsequent free-living conditions (20 hours). Results: In the controlled post-condition 4-hour period, no significant interaction (time × condition) was observed for all BP parameters (p ≥ 0.082). Similarly, during the subsequent 20-hour free-living ambulatory monitoring (diurnal and nocturnal), no differences between conditions were detected (p ≥ 0.094). A significant reduction in nighttime pulse pressure was observed in both HIIT4 and HIIT10 compared to REST (46 [44 ─ 50], 45 [42 ─ 53] vs. 50 [45 ─ 57] mmHg, respectively; p ≤ 0.018) with no differences between HIIT conditions (p = 0.316). Changes in nocturnal systolic BP approached but did not reach statistical significance (p = 0.068). Conclusions: This study suggests that in untrained older females living with T2D and HTN, the HIIT10 and HIIT4 protocols have very limited to no acute effect on post-exercise and ambulatory BP. The fact that the vast majority of participants had well-controlled office and ambulatory BP values as well as low cardiorespiratory fitness could explain these findings.