Low‐ and moderate‐intensity aerobic exercise acutely reduce blood pressure in adults with high‐normal/grade I hypertension

The aim of the study is to compare the acute effects of low‐ and moderate‐intensity aerobic exercise on post‐exercise blood pressure in active adults with high‐normal/grade I hypertension. Thirteen physically active adults (67.0 ± 8.7 years) randomly completed two aerobic exercise sessions of 30 minutes at low (30% heart rate reserve [HRres]) and moderate (60% HRres) intensity. Blood pressure was assessed pre‐session and every hour until 3 hours after. Systolic blood pressure decreased after both exercise intensities without significant differences between sessions at 1 hour after the session (30%: −10.0 ± 12.6% vs 60%: −11.4 ± 12.7 mm Hg, P > .05). Three hours after the 60% session, the systolic blood pressure remained significantly lower than baseline (139.9 ± 12.9 to 129.3 ± 11.9 mm Hg, P < .05), but without significant differences between sessions. No relevant changes were observed in diastolic and mean blood pressure. In conclusion, a single session of aerobic exercise acutely reduces systolic blood pressure in active adults with high‐normal/grade I hypertension.


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LOPES Et aL. same time of day (between 08:30 and 10:00 am) to account for diurnal variation in BP, separated by a minimum of 48 hours to avoid acute exercise effects, and completed within 2 weeks of the beginning of the study participation.

| Participants
Physically active adults (age ≥ 45 years old) with regular participation in an aerobic exercise training program (5 × 60 minutes sessions/ wk) for at least 12 months, and high-normal BP or essential grade I arterial hypertension 11 were recruited in a community exercise program. Both genres were included because the transient reduction in BP after exercise does not appear to be affected by genre. 12 Exclusion criteria: changes in hypertensive medication in the preceding 3 months, peripheral arterial disease, lung disease, cancer, or any other contraindication to exercise. The local review board approved the study; written informed consent was obtained, and all procedures were conducted in accordance with the Declaration of Helsinki.

| Procedures
Potential participants of a community exercise program were asked to participate. Those who agreed to participate received detailed explanations about the procedures, monitoring techniques, and apparatus, and visited the laboratory three times. On the first visit, the participants were introduced to the study protocol, procedures, and equipment for home BP self-assessment; then, clinical history, medication, body weight and height, resting office BP, and heart rate (HR) were assessed as recommended. 11 On the second and third visits, participants completed two randomly assigned exercise sessions, one at an intensity of 30% of the HRres and the other at 60%. To calculate the HRres, the theoretical maximum HR was calculated using the formula of Tanaka: 208 bpm − (age × 0.7). Each exercise session lasted 40 minutes, that is, 5 minutes of warm-up, 30 minutes of aerobic exercise on a treadmill, and 5 minutes of cool-down. HR (HR monitor) and levels of exertion (ie, Borg scale) were monitored during exercise sessions.
Blood pressure was self-assessed, with the participants seated, using a digital automatic BP monitor (M6; Omron Healthcare Co.) at rest 10 minutes before the exercise sessions, after the session (with supervision), and at 1, 2, and 3 hours (at home) after the end of the exercise session. Subjects were instructed to perform their habitual daily activities, to assess BP in a quiet room (replicating the conditions of the assessment previous to exercise) following the recommended procedures 11 and register the BP values in a standardized datasheet. In brief, participants were seated comfortably in a quiet environment for 5 minutes before BP and HR measurements.
The measurements were performed with the right arm, relaxed, on a table at heart level. Three measurements were made at intervals of 1 minute; the average of the last two measurements was recorded.
All subjects were asked to avoid strenuous exercise on the 48 hours before the visits and to have a light breakfast, without any stimulants (coffee, tobacco, and alcohol), no less than 2 hours before the start of the sessions. All subjects maintained the same antihypertensive treatment during the study period.

| Statistical analysis
diastolic BP changes at 1, 2, or 3 hours post-exercise (Table 1). In mean BP, there was a trend to decrease over time (P = .053) but no interaction between time and sessions (P = .342).

| D ISCUSS I ON
Our results indicate that both aerobic exercise intensities induced an immediate decrease in systolic BP. Even low-intensity exercisewhich can be more easily tolerated by older adults with hypertension-induced an immediate benefit in active adults.
The results observed in systolic BP are in line with those reported in a previous review that included 65 studies and showed an acute reduction of 8 mm Hg of systolic BP in hypertensive individuals. 10 In the present study, we observed a systolic BP decrease after the session between 8.7 and 10 mm Hg in the 30% session and between 10.5 and 11.4 mm Hg in the 60% session. A previous study in very old persons with hypertension, and without regular exercise practice, also showed that two periods of 10 minutes of walking at an intensity of 40% to 60% of the HRres acutely decreases systolic, but do not change diastolic BP. 13 The lack of significant reduction in diastolic BP is not surprising, since the baseline values were close to normal, making it is less likely to achieve a lower BP after an exercise bout. 10 Inactive subjects usually have a greater post-exercise reduction in BP than athletes. 10 Therefore, the fact that our study included only physically active adults and, even though, a considerable reduction of BP levels was observed, reinforces the value of exercise in the control of BP.
Regarding exercise intensity, Eicher et al 9 compared the antihypertensive effects of a single session of low, moderate, and vigorous intensity exercise among men with pre-to stage 1 hypertension and reported that higher exercise intensities elicited the largest BP reductions (2.8 ± 1.6, 5.4 ± 1.4, and 11.7 ± 1.5 mm Hg, respectively for low, moderate, and vigorous) compared to non-exercise control session over the course of 9 hours. Similar results were found in others studies, in which the decrease in BP after exercise was superior and longer after more intense aerobic exercise. 14 As post-exercise blood pressure reduction is influenced by baseline value, we reported the assessment of individual responses to exercise (Figure 1), which clearly shows that some of the participants were non-responders to both exercise intensities, while some of them showed a huge decrease in systolic BP. Those showing the largest decrease in BP were those who also showed the highest values at pre-exercise. This is in line with the current evidence suggesting that those with higher BP values before exercise exhibit a greater reduction post-exercise. 5 This study has some limitations. First, the short period of time   self-measurement of BP at home instead of ambulatory BP monitoring could be seen as a limitation. However, a recent study indicated that adults self-monitoring their BP at home showed greater adherence both to a supervised and unsupervised exercise, compared with those that did not use BP self-monitoring. 15 Third, in the present study we cannot conclude about post-exercise hypotension, as the formula used to assess the difference between BP levels pre-and post-exercise (post-exercise BP -pre-exercise BP) does not cover possible changes in BP that can occur independently of exercise (eg, circadian effects). 16 To determine post-exercise hypotension, a control session should be included. In addition, our sample was composed by participants with different characteristics (eg, sex and antihypertensive medication); although normotensive and hypertensive subjects present an acute reduction in blood pressure after exercise, the decrease is dependent on the pre-exercise levels of blood pressure.
In conclusion, the results of this study suggest that a single session of aerobic exercise acutely reduces BP in active adults even at low intensities of aerobic exercise. These results add evidence supporting the importance of physical activity as a nonpharmacological tool to control hypertension in this population. Even a low-intensity aerobic exercise session, which could be more easily tolerated by some older adults with hypertension, promoted an immediate benefit, and could be considered when aiming to control BP.

ACK N OWLED G M ENTS
iBiMED is a research unit supported by the Portuguese Foundation for Science and Technology (UID/BIM/04501/2020) and FEDER/ F I G U R E 1 Absolute change in systolic (SBP) and diastolic blood pressure (DBP) at 1 h, 2 h, and 3 h after aerobic exercise protocol at 30% and 60% intensities of heart rate reserve Compete2020 funds. CIDESD is a research unit supported by the Portuguese Foundation for Science and Technology within the project (UID/DTP/ 04045/ 2020).

CO N FLI C T O F I NTE R E S T
None.

AUTH O R CO NTR I B UTI O N S
All authors contributed to reviewing and revising the manuscript.