Twice or Four Times a Week? Exercise Frequency Does Not Matter for Blood Pressure Variability

Blood pressure is not a fixed number but a moving target, rising and falling with every heartbeat, every step, and every moment of stress throughout the day. In people with hypertension, these fluctuations can become exaggerated, and a growing body of evidence suggests that this instability, known as blood pressure variability, predicts cardiovascular death independently of how high the average pressure actually is. Now, a randomized clinical trial from Brazil has tackled a question that no study had directly addressed before: does it matter whether older adults with hypertension exercise twice a week or four times a week, as long as the total amount of exercise is the same? The answer, published in Frontiers in Rehabilitation Sciences, is a surprising no, but with an encouraging twist.

The trial, conducted between August 2022 and December 2024 at the Clinical Research Center of Hospital de Clínicas de Porto Alegre and the Exercise Research Laboratory of the Universidade Federal do Rio Grande do Sul, enrolled men and women aged 50 to 80 years with a previous diagnosis of hypertension. Participants were randomly assigned to a combined training program, which blends resistance exercises with aerobic exercise in a single session, performed either twice per week or four times per week for 12 weeks. The researchers adopted a deliberately pragmatic approach: the weekly exercise dosage was set at 120 to 160 minutes, and intensity was prescribed not by laboratory measurements but by how hard participants felt they were working, targeting scores of 4 to 6 on Borg’s modified CR10 perceived exertion scale. Crucially, the total weekly volume and overload were matched between the two groups, so the only real difference was how that exercise was distributed across the week.

The sessions themselves were simple and scalable. All training took place on an outdoor athletic track, beginning with bodyweight-based resistance exercises such as push-ups on street workout bars or the floor, inverted rows using an overhead strap, calf raises on a step, squats, and abdominal exercises, immediately followed by walking or running. Participants in the four-times-per-week group completed 10 to 15 minutes of resistance training followed by 20 to 25 minutes of aerobic exercise per session, while the twice-weekly group performed 20 to 30 minutes of resistance work followed by 40 to 50 minutes of aerobic exercise. The resistance intensity corresponded to roughly 50 to 60 percent of the estimated one-repetition maximum, and the aerobic component targeted about 60 percent of estimated peak oxygen uptake. Attendance was remarkably high in both arms, averaging 94.9 percent in the twice-weekly group and 93.6 percent in the four-times-per-week group.

To capture the instability of blood pressure, the researchers used ambulatory blood pressure monitoring, an automatic oscillometric device worn by participants that records systolic and diastolic pressure at intervals throughout a full 24 hours, including daytime and nighttime periods. The team calculated variability using two complementary indices. The standard deviation reflects how widely blood pressure values scatter around the mean, while the average real variability, or ARV, captures the average absolute difference between successive readings, weighted for the time intervals between them. ARV is considered the more informative measure because it respects the temporal sequence of fluctuations, reflecting the beat-to-beat instability that standard deviation ignores. Assessments were performed at baseline and after the 12-week intervention, with outcome assessors blinded to group allocation.

Of the 98 participants randomized in the parent RADAH trial, 47 with attendance of at least 80 percent and valid recordings at both assessments were analyzed: 27 in the twice-weekly group and 20 in the four-times-per-week group. The statistical models, built on generalized estimating equations, revealed no significant group-by-time interaction for any variability outcome, meaning that the two training frequencies produced statistically indistinguishable effects. But within both groups, something meaningful happened. The four-times-per-week group reduced 24-hour systolic ARV by 2 mmHg and daytime systolic ARV by 3 mmHg, while the twice-weekly group achieved reductions of 1 mmHg and 2 mmHg respectively, all statistically significant. Only the twice-weekly group showed a significant reduction in daytime diastolic ARV, by 1 mmHg. Notably, the standard deviation-based indices remained unchanged across the board, suggesting that the training smoothed out reading-to-reading fluctuations rather than narrowing the overall scatter of values.

The daytime confinement of these effects is consistent with the wider literature. A meta-analysis of exercise training studies reported larger effects on daytime than on nighttime variability, and randomized trials of aerobic and combined training have similarly found reductions in daytime but not nighttime systolic variability. The pattern also aligns with prior work showing that combined training performed three times per week reduced 24-hour, daytime, and nighttime systolic ARV in older adults with hypertension, with total weekly exercise volumes similar to those used here. By contrast, a study of postmenopausal women that prescribed only 120 minutes per week, substantially less than the present trial, found no change in short-term variability despite reductions in mean blood pressure. Taken together, these comparisons suggest that total weekly exercise volume, rather than how frequently sessions are scheduled, may be the key determinant of reductions in systolic blood pressure variability, although the authors caution that this interpretation remains hypothesis-generating because the analysis was not powered to compare frequencies directly.

Why does variability matter at all? In an observational cohort of older adults, each 2 mmHg higher 24-hour systolic ARV was associated with higher mortality and cardiovascular risk, independently of mean blood pressure. The reductions observed in this trial, ranging from 1 to 3 mmHg, therefore fall within a range that has been linked to clinically relevant differences in risk. The mechanisms underlying the daytime systolic reduction are compatible with improved arterial buffering and central hemodynamics, since aerobic training is known to lower central systolic pressure alongside daytime variability. The autonomic contribution is less certain, as aerobic training can improve autonomic modulation without measurable changes in blood pressure variability. The researchers also considered post-exercise hypotension, the acute blood pressure reduction that follows each session, as a potential driver of chronic adaptations, but prior work showing that acute reductions in ARV are not maintained after chronic training suggests that this outcome may depend more on the total amount of exercise performed than on session frequency alone.

The trial has important limitations that shape how the findings should be read. This was a secondary, per-protocol analysis restricted to adherent participants, which may have introduced selection bias and partially compromised the benefits of randomization. A software failure and data export problems meant that individual readings were unavailable for 16 adherent participants, reducing the sample size and precluding an intention-to-treat analysis. The use of angiotensin-converting enzyme inhibitors was more prevalent in the four-times-per-week group at baseline, but a sensitivity analysis accounting for this imbalance left the within-group reductions unchanged, and the group-by-time interaction remained non-significant after accounting for multiple testing. The absence of a non-exercising control group also limits the ability to attribute the observed reductions solely to training, as regression to the mean or temporal variation could contribute. Moreover, whether exercise-induced reductions in short-term blood pressure variability translate into improved cardiovascular outcomes remains uncertain, since the trial was not designed to evaluate clinical endpoints.

Despite these caveats, the study offers a genuinely useful message for the millions of aging adults managing hypertension. Twelve weeks of combined training, performed with the same total weekly volume whether distributed across two or four sessions, smoothed out short-term systolic blood pressure fluctuations in both groups, with no evidence that training four times a week conferred an advantage. For patients and clinicians, this suggests that the frequency of exercise sessions can be tailored to individual preferences, schedules, and adherence capacity without sacrificing the cardiovascular benefits of a matched weekly dose. The pragmatic design, using minimal infrastructure and perceived exertion rather than laboratory-based intensity targets, makes the intervention easily scalable to real-world environments. As the evidence on exercise and blood pressure variability continues to mature, this trial provides a critical piece of the puzzle, helping to optimize non-pharmacological strategies for hypertension management in an aging population.

Subject of Research: Health

Article Title: Effects of different weekly frequencies of combined training on blood pressure variability in aging adults with hypertension

Article References: Domingues, L. B., Mallmann Schneider, V., Carpes, L., Fuchs, S. C., & Ferrari, R. (2026). Effects of different weekly frequencies of combined training on blood pressure variability in aging adults with hypertension. Frontiers in Rehabilitation Sciences, 7, Article 1925760. https://doi.org/10.3389/fresc.2026.1925760

Image Credits: AI Generated

DOI: 10.3389/fresc.2026.1925760

Keywords: blood pressure variability, hypertension, combined training, exercise frequency, aging adults, ambulatory blood pressure monitoring, average real variability, randomized clinical trial, cardiovascular risk, exercise training, Effects, different