Long-Term Habitual Vigorous Physical Activity Is Associated With Lower Visit-to-Visit Systolic Blood Pressure Variability: Insights From the SPRINT Trial Free

Abstract

Background

Our work aimed to investigate the association between vigorous physical activity and visit-to-visit systolic blood pressure variability (BPV).

Methods

We conducted a post hoc analysis of SPRINT (Systolic Blood Pressure Intervention Trial), a well-characterized cohort of participants randomized to intensive (<120 mm Hg) or standard (<140 mm Hg) systolic blood pressure targets. We assessed whether patients with hypertension who habitually engage in vigorous physical activity would have lower visit-to-visit systolic BPV compared with those who do not engage in vigorous physical activity. Visit-to-visit systolic BPV was calculated by SD, average real variability (ARV), and SD independent of the mean (SDIM) using measurements taken during the 1-, 2-, 3-, 6-, 9-, and 12-month study visits. A medical history questionnaire assessed vigorous physical activity, which was divided into 3 categories according to the frequency of vigorous physical activity.

Results

A total of 7,571 participants were eligible for analysis (34.8% female, mean age 67.9 ± 9.3 years). During a follow-up of 1-year, vigorous physical activity could significantly reduce SD, ARV, and SDIM across increasing frequency of vigorous physical activity. There were negative linear trends between frequency of vigorous physical activity and visit-to-visit systolic BPV.

Conclusions

Long-term engagement in vigorous physical activity was associated with lower visit-to-visit systolic BPV.

Clinical trials registration

SPRINT (Systolic Blood Pressure Intervention Trial); Trial Number: NCT01206062, https://clinicaltrials.gov/ct2/show/NCT01206062.

Although the adverse cardiovascular consequences of hypertension are thought to depend mainly on mean blood pressure (BP) values, increasing evidence indicates that these outcomes might also depend on BP variability (BPV), which includes short- and long-term substantial variations in BP.¹ Long-term BPV, as exemplified by visit-to-visit systolic BPV, is a reproducible and not a random phenomenon.² This long-term fluctuation is most common in elderly patients as a consequence of reduced elasticity/compliance of large arteries, which induces high BPV mainly through sympathetic nerve activation and impaired baroreflex sensitivity.³ Although age-related arterial stiffness in most large arteries is intrinsic to the aging process, previous research demonstrated regular physical activity had been shown to reduce age-related stiffness of the small and large arteries in both middle-aged and elderly men.⁴ Specifically, previous cross-sectional studies demonstrated that habitual vigorous aerobic exercise appeared to benefit arterial compliance in middle-aged and elderly populations such that their compliance was greater than age-matched sedentary adults.^5,6 Whether vigorous physical activity can further reduce the visit-to-visit systolic BPV by the above mechanisms is still not clear. Therefore, the aim of the present study is to investigate the association between vigorous physical activity and visit-to-visit systolic BPV. We hypothesized that patients with hypertension who habitually engage in vigorous physical activity would have lower visit-to-visit systolic BPV compared with those who do not engage in vigorous physical activity.

METHODS

Eligibility for analyses

Details of Systolic Blood Pressure Intervention Trial (SPRINT) had been described previously.⁷ Namely, 9,361 individuals ≥50 years, at high risk for or with cardiovascular disease, a systolic BP of 130–180 mm Hg, but without diabetes, were randomized to intensive (target <120 mm Hg) vs. standard (target <140 mm Hg) BP control.⁷ The sample for primary analyses was restricted to SPRINT participants who had 1-, 2-, 3-, 6-, 9-, and 12-month study visits. Participants with cardiovascular events and mortality during the time of assessment were excluded. Self-reported physical activity was assessed at enrollment by a medical history questionnaire detailing participants’ intensity together with duration or frequency of physical activities over the previous 1 year, using items in the Saltin-Grimby Physical Activity Level Scale (SGPALS) questionnaire.⁸ The questionnaire demonstrated good validity⁹ and was shown to be related to cardiovascular risk factors.^9,10 Participants responded to 2 questions, which measured 2 levels of physical activity. One was for vigorous-intensity physical activities, they were asked, “Please think over the last year and indicate how often you participate in vigorous activities like recreational activities or conditioning exercises?” The response options were rarely or never, 1–3 times per month, 1 time per week, 2–4 times per week, and 5+ times per week. Another was for moderate-intensity physical activities, participants were asked, “On average, how much time do you spend doing these moderate-intensity activities like brisk walking, climbing stairs or vacuuming floors?” and were given the following response options: 0–15 minutes per day, 15–30 minutes per day, 30–60 minutes per day, 1–4 hours per day, and 4 or more hours per day. In order to investigate a dose–response relationship between vigorous physical activity and visit-to-visit systolic BPV, each participant was assigned to one of the following three categories according to the frequency of vigorous activities. (i) Category 1, rarely or never vigorous physical activity; (ii) category 2, vigorous physical activities less than 2 times weekly; (iii) category 3, vigorous physical activities 2 or more times weekly. The SPRINT data set for this analysis was obtained from the National Heart, Lung, and Blood Institute’s Biologic Specimen and Data Repository Information Coordinating Center after having received a waiver for secondary use by the institutional review board at Rutgers University.

Statistics

Continuous variables were described as mean and SD and compared using T-test or Mann–Whitney U test. Categorical variables were presented as counts and percentages and compared using χ  ² test. Visit-to-visit systolic BPV was expressed as 3 candidate metrics which were widely used in BPV study^11,12: SD, average real variability (ARV), and SD independent of mean (SDIM). We used linear regression to calculate the adjusted mean difference (i.e., regression coefficients) in SD, ARV, and SDIM of systolic BP between category 2 or 3 and category 1 (reference groups). Three levels of adjustment were performed: model 1 adjusted age, race/ethnicity, gender, randomization site, and practice type; model 2 included variables in model 1 and estimated glomerular filtration rate, body mass index, smoking status, clinical or subclinical cardiovascular disease, baseline systolic and diastolic BP, prerandomization antihypertensive medication, moderate-intensity physical activities, and randomization assignment; model 3 included variables in model 2 and adjusted the following variables measured between 1- and 12-month postrandomization: mean systolic and diastolic BP, mean number of antihypertensive medications, antihypertensive medication changes, antihypertensive medication classes, nonadherence, aspirin, and statin use.¹¹ Linear trends in mean and adjusted mean difference were evaluated using 1-way analysis of variance and linear regression analysis, respectively. All analyses were performed using SPSS software (IBM SPSS Statistics 21, IBM Corp., Armonk, NY), with a 2-tailed P value of <0.05 considered statistically significant.

RESULTS

A total of 7,571 participants were included in the primary analysis (34.8% female, mean age 67.9 ± 9.3 years). The proportion of patients in category 1 was 1,983 (26.2 %), category 2 2,075 (27.4 %), and category 3 3,513 (46.4 %). Patients in category 1 were older, higher body mass index, more female, and tended to be Hispanic or Black adults than that of the other 2 groups (Supplementary Table S1 online). Patients in category 1 engaged in significantly less moderate- and vigorous-intensity physical activity (Supplementary Table S1 online). Though there showed no significant difference among 3 groups at the baseline and mean systolic BP during follow-up, in terms of medication, patients in category 1 used more antihypertensive drugs during follow-up, while with worse antihypertensive medication adherence (Supplementary Table S1 online).

There was a highly significant decrease in SD, ARV, and SDIM across the increasing category of vigorous physical activity (Table 1). Multivariable adjustment attenuated these trends, but did not offset the negative association between vigorous physical activity and visit-to-visit systolic BPV. Further, linear trends across categories remained significant after multivariate adjustment (Table 1).

It is worth mentioning that in comparison to patients in category 1, patients in categories 2 and 3 also engaged in more moderate-intensity physical activity (Supplemental Table S1 online), which, however, did not show a dose–response relationship with visit-to-visit systolic BPV (Supplementary Table S2 online).

Discussion

Over the years, mounting evidence indicates that high visit-to-visit systolic BPV is associated with increased risk for stroke, coronary events, and mortality independent of mean systolic BP.^13,14 Furthermore, cardiovascular protection has been found to be greater when BP control is accompanied by lower visit-to-visit systolic BPV.¹⁵ This implies that physicians should pay attention to consistency of BP control over time. To date, limited evidence suggests that visit-to-visit systolic BPV may be reduced by improving medication adherence,¹¹ treatment of generalized anxiety disorder,¹⁶ continuous positive airway pressure in patients with obstructive sleep apnea,¹⁷ using long-acting dihydropyridine calcium antagonists,¹⁸ but the possible clinical benefits from these approaches have not yet been fully demonstrated thus far. Physical activity is recommended as a critical component of lifestyle therapy for the primary prevention and treatment of hypertension. Evidence suggests that vigorous aerobic exercise could improve vascular compliance. Therefore, the present study aims to investigate the association between vigorous physical activity and visit-to-visit systolic BPV. Overall, our study demonstrates, for the first time, that there is a negative association between frequency of vigorous physical activity and visit-to-visit systolic BPV. That is, long-term habitual vigorous physical activity was associated with lower visit-to-visit systolic BPV.

2018 Physical Activity Guidelines for Americans recommend that aerobic physical activity preferably should be spread throughout the week, with exercise at least 3 days a week producing health benefits.¹⁹ 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease states physical activity even if it is below the recommended amount (≥150 minutes/week of moderate-intensity physical activity or ≥75 minutes/week of vigorous-intensity physical activity), can be beneficial to reduce cardiovascular risk.²⁰ However, the effect of physical activity on arterial compliance appears to depend on the intensity of physical activity.^4–6 Tanaka et al. found in healthy men (aged 18–77 years), regular vigorous aerobic-endurance exercise could modulate age-related stiffening of large arteries, whereas less strenuous exercise may not.⁶ Accordingly, our finding suggests that in case of BP control, vigorous-intensity physical activity may be necessary to decrease visit-to-visit systolic BPV—and potential outcomes.

Some limitations of this study should be acknowledged. First, the paucity of the duration of vigorous physical activity made a quantitative analysis by activity duration unfeasible. Second, physical activity is self-reported and not objectively assessed. Third, there is no assessment of light or nonintentional physical activity. Fourth, 1,790 (19%) of SPRINT participants were excluded in this manuscript because of missing variables and/or failing requirements for this analysis. Finally, as post hoc analyses involved comparisons of nonrandomized groups, a prospective randomized controlled study is needed to assess the findings of this study.

Long-term engagement in vigorous physical activity is associated with lower visit-to-visit systolic BPV. This finding raises the possibility of intervention to achieve consistent BP control over time, which might favor cardiovascular protection.

DISCLOSURE

The authors declared no conflict of interest.

DATA AVAILABILITY

All relevant data supporting the conclusions of this article are included within the article.

References

Author notes