Effects of High-Intensity Interval Training Versus Moderate-Intensity Continuous Training On Blood Pressure in Adults with Pre- to Established Hypertension: A Systematic Review and Meta-Analysis of Randomized Trials

Background Aerobic exercise reduces blood pressure (BP), but it is unknown whether a high-intensity training approach can elicit a greater BP reduction in populations with elevated BP. This systematic review compared the efficacy of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) for reducing BP in adults with pre- to established hypertension. Methods Five electronic databases (MEDLINE, EMBASE, CENTRAL, PEDro, and SPORTDiscus) were searched for randomized trials comparing the chronic effects of HIIT versus MICT on BP in individuals with resting systolic BP >= 130 mmHg and/or diastolic BP >= 85 mmHg and/or under antihypertensive medication. Random-effects modelling was used to compare changes from pre- to post-intervention in resting and ambulatory BP between HIIT and MICT. Changes from pre- to post-intervention in maximal oxygen uptake ((V) over dotO(2max)) between HIIT and MICT were also meta-analyzed. Data were reported as weighted mean difference (MD) and 95% confidence interval (CI). Results Ambulatory BP was excluded from the meta-analysis due to the limited number of studies (two studies). Comparing changes from pre- to post-intervention, no differences in resting systolic BP (MD -0.22 mmHg [CI 95%, -5.36 to 4.92], p = 0.93, I-2 = 53%) and diastolic BP (MD - 0.38 mmHg [CI 95%, -3.31 to 2.54], p = 0.74, I-2 = 0%) were found between HIIT and MICT (seven studies; 164 participants). HIIT improved (V) over dotO(2max) to a greater magnitude than MICT (MD 2.13 ml/kg/min [CI 95%, 1.00 to 3.27], p < 0.01, I-2 = 41%) with similar completion rates of the intervention and attendance at the exercise training sessions (nine studies; 245 participants). Limited data were available to compare the incidence of adverse events between HIIT and MICT. Conclusion HIIT and MICT provided comparable reductions in resting BP in adults with pre-to established hypertension. HIIT was associated with greater improvements in (V) over dotO(2max) when compared to MICT. Future randomized trials should investigate the efficacy of HIIT versus MICT for reducing ambulatory BP in adults with pre-to established hypertension. Registration PROSPERO registration (2016: CRD420160 41885).