ABC | Volume 115, Nº1, July 2020

Original Article Perrier-Melo et al. Post-Exercise Hypotension: Interval Vs. Continuous Arq Bras Cardiol. 2020; 115(1):5-14 and IE, despite being documented mainly after CE, which is the basis for hypertension prevention and treatment recommendations. 3,9 However, in recent years, IE, whether at vigorous or maximum intensity (“all out”), has been considered an alternative to CE for the improvement of several cardiovascular parameters, such as cardiorespiratory capacity, 17 vascular function 18 and clinical BP. 19 However, it is important to highlight that no direct comparisons were made on the acute effects of CE and IE on BP. Thus, it is not clear whether there is a superiority of the acute antihypertensive effect between exercises, which is an important knowledge gap, as it can help professionals in both hypertension prevention and treatment. Therefore, the aim of this systematic review and meta-analysis was to compare the magnitude of PEH between CE and IE in adults. Methods Literature search strategy The systematic review was carried out following the guidelines of the ‘Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA)’. 20 The search for the articles was carried out in PubMed, Web of Knowledge, Scopus and CENTRAL electronic databases. The search strategy used the following descriptors and free terms: “high intensity interval training” [MeSH Terms] OR “high intensity interval exercise” [TIAB] OR “aerobic interval training” [TIAB] OR “aerobic interval exercise” [TIAB] OR “sprint training” [TIAB] OR “sprint” [TIAB] OR “sprint exercise” [TIAB] OR “sprint interval exercise” [TIAB] AND “blood pressure” [MeSH Terms] OR “post-exercise hypotension” [Mesh Terms] OR “post-exercise hypotension” [Mesh Terms] OR “hypotension” [Mesh Terms]. All processes for article search, selection and evaluation were carried out in duplicate and independently. Eligibility criteria The eligibility criteria were established according to the PICOS (Population, Intervention, Comparator, Outcomes and Study Design) question. Population This review included studies involving adults (18 years or older) of both genders, with no restriction regarding the level of physical activity and BP classification (normotensive, pre- hypertensive and hypertensive). Mean pre-exercise systolic and diastolic BP values were used to classify individuals regarding BP, following the same procedures as other systematic reviews 19,21 and the 7 th Brazilian Guidelines on Hypertension. 3 Intervention The classification system for IE proposed by Weston et al. 22 was used to define the eligibility criteria for this intervention. According to this proposal, repeated stimuli at vigorous intensity (80-100% of peak heart rate - HRpeak) interspersed with periods of recovery (active or passive) are classified as high-intensity interval training, and maximum stimuli (“all out”; or above the peak oxygen consumption load -VO 2 peak) interspersed with recovery periods (active or passive) are classified as sprint interval exercise. Studies that used the percentage of VO 2 peak, VO 2 reserve or rating of perceived exertion (RPE) equivalent to 80-100% of HRpeak according to the American College of Sports Medicine, 23 were considered eligible, as well as the “all out” protocols. Studies that showed interventions associated with IE, such as another form of exercise (e.g., strength exercises) or nutritional strategy, were not considered for inclusion. Comparator The CE was considered as a comparator of the IE. Studies that used the percentage of VO 2 peak, VO 2 reserve or RPE equivalent to moderate intensity (i.e., 64-76% of HRpeak) or vigorous intensity (i.e. 77-95% of HRpeak) were considered eligible. Studies that showed interventions associated with CE, such as another type of exercise or nutritional strategy, were not considered for inclusion. Outcomes The primary outcome of this review was clinical BP, measured between 45 and 60 minutes post-exercise. This post-exercise time was defined considering that most studies that investigated the effects of CE and IE included measures within that period. Therefore, even though the study analyzed BP beyond 60 minutes post-exercise, this measure was not considered for the meta-analysis. Study Design Crossover studies were considered, involving a session of CE and IE, randomized performance order, in English or Portuguese. The search was carried out without a date limit and ended in March 2020. Data extraction An electronic spreadsheet was used to extract data from the included articles, according to the eligibility criteria, in duplicate and independently. In case of disagreement, a meeting was held, and a consensus was established between the researchers. The characteristics of the study participants (age, gender, body mass index, level of physical activity, BP classification), characteristics of the exercise sessions (modality, environments, duration, intensity and time spent in the training session), method of BP measurement and post-exercise BP measurement period were extracted and recorded. Absent data in the texts were requested directly from the authors. Evaluation of study methodological quality The ‘Tool for the assEssment of Study qualiTy and reporting in Exercise (TESTEX)’ scale was used to assess the methodological quality of the included studies, 24 also in duplicate and independently. In case of disagreement, a meeting was held, and consensus was established between the researchers. 6