Our main results were that 61% (17 out of 28) of the included studies reported attenuated BP peaks (either in SBP, DPB and/or MBP) after acute exercise and none showed deleterious results from the exercise. The metanalytic results suggest that acute exercise attenuates BP reactivity to stress. This effect occurred mutually in SBP (SMD = -0.35 [-0.46; -0.23]), DBP (SMD = -0.49 [-0.68; -0.30]) and MBP (SMD = -0.48 [-0.70; -0.26]) in magnitudes similar to previous meta-analyze about the effects of acute aerobic exercise (SBP Effect size = 0.38; DBP Effect size = 0.40) . Besides that, only 22% of the studies included non-aerobic exercises which make the results for these exercise mode difficult to generalize. Lastly, there is a scarcity of studies with hypertensive individuals (11%) and with a population over 40 years old (11%).
In this sense, we reaffirm the need for studies with high cardiovascular risk patients, since these responses contribute to the construction of the clinical picture of these patients and may indicate an increase in left ventricular mass , augmented carotid atherosclerosis , increased risk of cardiovascular mortality , development of hypertension , and an increased risk of developing several cardiovascular diseases [2,4]. We also extend this need for studies with the elderly, who, in addition to having the aforementioned advantages for having a high incidence of cardiovascular diseases , seem to have very promising responses when compared to younger people , so studies exploring specific age stratus are needed. We also emphasize that, in addition to expanding and confirming favorable responses to aerobic exercise , the present study is, as far as we know, the first to demonstrate positive meta-analytic effects of resistance exercise in BP reactivity. It is worth mentioning that these results are anchored in a smaller volume of evidence, and should be interpreted with caution, but it provides an optimistic direction for future studies with this exercise mode.
Regarding intervention characteristics, studies that compare different exercise loads showed mixed results. As an example, three studies evaluated different exercise intensities and one was favorable to higher intensities , another obtained a very discreet advantage at greater intensities , and the latter found no differences between groups . Concerning exercise session duration, a study shows favorable effects of longer sessions , and the others found no differences [27, 41]. Finally, a study compared continuous aerobic exercise of moderate intensity with high intensity interval exercise and also found no significant differences . Thus, evidence on differences arising from the characteristics of exercise load control is still scarce, therefore a meta-analysis clustering intensity groups was not possible. However, the evidence is greater in moderate exercises for 30 to 60 minutes.
Overall, when exploring studies heterogeneity, we found that reductions in peak DBP appear to be more heterogeneous than those in SBP. In addition, the greatest effects found are usually in subgroups with fewer studies, and most of the heterogeneity seems to be driven by studies published before the year 2000. So, regarding the effect on DBP response, several results must be highlighted. The first is that, in sex comparisons, the high heterogeneity in men (i² = 77) draws attention and seems to be explained by Ebbesen et. al study . This study has a very favorable effect on exercise and is not overlapping with other studies, and with its omission we have important reductions in heterogeneity and effect size (i² = 0; SMD = -0.28[-0.47; -0.09]). The large volume of exercise in this study (from 60 to 120 min) may also explain this difference. Also, there is an important heterogeneity related to studies that include both sexes (i² = 74%). A point that still draws a lot of attention in comparisons by sex, is the large effect size related to studies without a defined sex (-1.16 [-1.72; -0.59]). However, this subgroup has only 2 studies, and one of them  has an exceptionally large effect (-2.06 [-3.28; -0.85]).
Besides that, there is high heterogeneity in studies with aerobic exercise (i² = 74%). The main characteristics of these studies that may explain their differences to the others in the subgroup are the inclusion of hypertensive patients [26, 34], the high volume of exercise (from 60 to 120 min)  and the self-selected exercise intensity strategy . Regarding the studies with resistance exercises, the heterogeneity is significantly reduced (from i² = 54%, to i² = 0%, with SMD = -0.65[-0.95; -0.36]) with the omission of one study . This heterogeneity might be explained by the alternative training with an intensity much higher than that of other studies (eccentric phase training at 120% of 1 repetition maximum test). Furthermore, the high heterogeneity (i² = 88%) and the moderate effect size (-0.79 [-1.45; -0.12]) in studies with RCT design are also noteworthy. In this regard, when we remove the study from Ebbesen et. al , drastically reduces the heterogeneity and effect size of the subgroup (i² = 0%; SMD = -0.19[-0.49; 0.11]). This might be explained by the large volume of exercise in this study (from 60 to 120 min) compared to the others in the subgroup (3 to 45 minutes).
Considering types of stressors, there are moderate effects in studies that present physical tests (isolated or both), but mental tests alone have small effects. This may indicate greater effects of exercise in situations of physical stress than in situations of mental stress. Furthermore, the high heterogeneity of the group with associated physical and mental stressors (i² = 86%) draws attention, but it was expected due to the heterogeneity of the stress tests. However, 2 studies stand out in this subgroup for not having results that overlap with the others [27, 34]. The main characteristics of these studies that can explain their differences in relation to the others in the subgroup are the large volume of training (from 60 to 120 min) in one study  and the inclusion of hypertensive patients in the other . The omission of these studies reduces the heterogeneity (i² = 0%) and the effect size (0.00 [-0.35; 0.35]), generating a situation in which studies with isolated effects have effects weak to moderate while in tests with both associated have null effects. These studies also have no overlap with the others from the multiple stressors subgroup, and their omission generates a reduction in heterogeneity (from i² = 83%, to i² = 0%) and in effect size (from 0.69 [-1.18; -0.20], to -026 [-0.50; -0.01]).
Another source of heterogeneity could be the fact that several stress tests were used, from classically standardized and widely used protocols such as the Cold pressor test  to less restricted but with greater ecological validity as studying situations . In this sense, we believe that a convergence of these characteristics is necessary, to combine sufficient standardization of methods with greater continuity with the stress experienced in daily life . Thus, studies with multiple stressors such as the Trier Social Stress Test (that includes public speaking with simulated job interview and arithmetic task) and the Maastricht Acute Stress Test (that includes cold pressure stress, negative feedback and arithmetic task) seem to be good alternatives for future studies .
As the types of stressors, their mechanisms of action are also diverse. So, when a stressful situation is imposed, it generates a response that includes diverse mechanisms [1–3], such as: neural-network (specially salience, executive control, and default mode networks) [54, 55], autonomic system [56, 57], catecholamines [3,58], cortisol [59, 60], and opioids/β endorphin [61, 62]. So, the isolated and interaction effects  of these mechanisms may explain the BP reactivity to stress [3,64]. Exercise, in turn, seems to mitigate stress reactivity by reducing vascular resistance , norepinephrine  and hypothalamic pituitary-adrenal axis responses , in addition to causing increased β2-mediated vasodilation  and levels of endorphins . Finally, there are also psychosocial effects of exercise such as improved self-efficacy and distraction from negative feelings .
It should be emphasized that the present review has some limitations, such as the multiplicity of stress tests and exercise prescrition, which makes difficult generalize the results. Besides that, these results are mostly in healthy and young populations and therefore cannot be easily generalized to populations with different health conditions. Thus, in future studies, we encourage the research of stressors similar to everyday life, involving different situations, sensations, emotions, and specially extended stressors like those found in sports, social fragility, and scholar/work environment. In this sense, we highlight a study , which despite achieving null results, has an interesting approach with great ecological validity (40 minutes studying with undergraduate students). Finally, we also encourage studies that allow a better understanding of exercise load control (e.g., intensity, volume), and in older populations with different morbidities, that can help to improve individual intervention strategies.