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Background: The 24-h activity cycle (24H-ACT) (sleep, sedentary behavior, light physical activity, and moderate to vigorous physical activity) may have deleterious or beneficial associations with 24-h blood pressure (24H-BP)., Purpose: Estimate the short-term associated changes in 24H-BP with acutely replacing 30 min/d from one behavior of the 24H-ACT to other behaviors in employed adults., Methods: Participants (N = 659) wore an ambulatory blood pressure monitor and two accelerometers (waist and wrist) to measure 24H-BP and the 24H-ACT., Results: Replacing 30 min of sedentary behavior with 30 min of sleep was associated with lower 24-h mean systolic [ß = -0.32 mm Hg per 0.5 h (95% CI: -0.58, 0.06)] and diastolic [ß = -0.31 mm Hg per 0.5 h (95% CI: -0.50, -0.12)] blood pressure. Replacing 30 min of light physical activity with 30 min of sleep was associated with lower 24-h mean systolic [ß = -0.30 mm Hg per 0.5 h (95% CI: -0.62, 0.03,)] and diastolic blood pressure [ß = -0.34 mm Hg per 0.5 h (95% CI: -0.58, -0.11)]. No other time reallocations between 24H-ACT behaviors were associated with changes in 24H-BP., Conclusion: Replacing time in sedentary behavior or light physical activity with sleep may provide small short-term reductions in that day's 24H-BP., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Journal of Hypertension, Ltd. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

This paper introduces functional quantile principal component analysis (FQPCA), a dimensionality reduction technique that extends the concept of functional principal components analysis (FPCA) to the examination of participant-specific quantiles curves. Our approach borrows strength across participants to estimate patterns in quantiles, and uses participant-level data to estimate loadings on those patterns. As a result, FQPCA is able to capture shifts in the scale and distribution of data that affect participant-level quantile curves, and is also a robust methodology suitable for dealing with outliers, heteroscedastic data or skewed data. The need for such methodology is exemplified by physical activity data collected using wearable devices. Participants often differ in the timing and intensity of physical activity behaviors, and capturing information beyond the participant-level expected value curves produced by FPCA is necessary for a robust quantification of diurnal patterns of activity. We illustrate our methods using accelerometer data from the National Health and Nutrition Examination Survey, and produce participant-level 10%, 50%, and 90% quantile curves over 24 h of activity. The proposed methodology is supported by simulation results, and is available as an R package., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. [br]For permissions, please e-mail: journals.permissions@oup.com.)

Wearable physical activity monitors (PAMs) have potential to positively influence physical activity. However, high rates of disengagement have been reported, which dampens enthusiasm, as these devices are unlikely to impact habitual physical activity if they are not worn for a sustained period of time. The purpose of this study was to identify demographic and device-use characteristics (e.g., data sharing) associated with sustained device engagement. Current PAM users (n = 418; mean age: 35.0 ± 12.5; 78% female) from across the USA were recruited online and completed a baseline web-based survey in 2015-2016 comprising questions about demographics and device use. Participants were followed-up again in 2017, at which time they reported whether or not they still used a PAM. Sustained PAM engagement was defined as those who continued use at follow-up. The median follow-up time was 15.5 (±3.7) months. In fully adjusted models, the following were significantly associated with long-term engagement: age (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.01-1.05, p = .014), Hispanic ethnicity (OR: 3.67; 95% CI: 1.20-11.26, p = .023), running as a preferred exercise (OR: 1.82; 95% CI: 1.02-3.24, p = .043), wanting to monitor health variables as a reason for choosing to use a PAM (OR: 1.73; 95% CI: 1.02-2.92, p = .042), and sharing data from the PAM publicly on social media (e.g., Facebook and Twitter; OR: 5.11; 95% CI: 1.64-15.93, p = .005). A number of sociodemographic and use characteristics were associated with sustained device use over a median follow-up of 1.3 years. One modifiable factor that may lead to longer device engagement is encouraging users to share data publicly., (© Society of Behavioral Medicine 2019. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Little is known concerning the type of activity that should be substituted for sedentary time and its potentially most hazardous form (prolonged sedentary bouts) to impart health benefit. We used isotemporal substitution techniques to examine whether 1) replacing total sedentary time with light-intensity or moderate to vigorous physical activity (LIPA or MVPA) or 2) replacing prolonged sedentary bouts with shorter sedentary bouts is associated with reductions in all-cause mortality risk. Participants (n = 7,999) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national cohort of US adults aged ≥45 years, were studied. Sedentary time was measured by accelerometry between 2009 and 2013. There was a beneficial association with mortality risk for replacing total sedentary time with both LIPA (per 30 minutes, hazard ratio (HR) = 0.83; 95% confidence interval (CI): 0.80, 0.87) and MVPA (per 30 minutes, HR = 0.65; 95% CI: 0.50, 0.85). Similarly, there was a beneficial association for replacing prolonged sedentary-bout time with LIPA and MVPA but not for replacement with shorter sedentary bouts (per 30 minutes, HR = 1.00; 95% CI: 0.96, 1.03). These findings suggest short sedentary bouts still carry mortality risk and are not a healthful alternative to prolonged sedentary bouts. Instead, physical activity of any intensity is needed to mitigate the mortality risks incurred by sedentary time., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Context: Time spent in moderate-to-vigorous physical activity (MVPA), but not in sedentary behavior (SB), is related to cardiometabolic risk among non-Hispanic white youth., Objective: Examine associations of SB and MVPA with cardiometabolic risk factors among Hispanic/Latino youth., Design: Cross-sectional analysis., Setting: Four US communities., Participants: Hispanic/Latino youth (N = 1,426) ages 8 to 16 years., Measurements: Associations of MVPA and SB, measured using 7-day accelerometer data (independent variables), with markers of glucose and lipid metabolism, inflammation, and endothelial function (dependent variables), were assessed in multivariable linear regression models while adjusting for sociodemographic characteristics and accelerometer wear time. Additional models controlled for obesity measures., Results: SB comprised a mean (SD) of 75% (13%) of accelerometer wear time; mean (SD) time of MVPA was 35 min/d (22 min/d). Deleterious levels of high-density lipoprotein-cholesterol (HDL-C), triglycerides, insulin resistance, C-reactive protein, and plasminogen activator inhibitor-1 were associated with lower levels of MVPA and higher levels of SB (all P < 0.05). Associations of MVPA with log-transformed triglyceride concentrations (β per 15-min/d increment, -0.039; SE, 0.018; P = 0.037) and SB with HDL-C (β per 30-min/d increment, -0.63; SE, 0.26; P = 0.018), but not those with other markers, remained significant after adjusting for MVPA or SB and further adjustment for body mass index and waist circumference. Higher SB tertiles were associated with lower soluble receptor for advanced glycation end products in fully adjusted models (P for trend = 0.037)., Conclusions: Physiological precursors of diabetes and cardiovascular disease were associated with MVPA and SB among US Hispanic/Latino youth, a group that bears a disproportionate burden of metabolic disorders.

Background: Psychosocial stress contributes to heart disease in part by adversely affecting maintenance of health behaviors, while exercise can reduce stress. Assessing the bi-directional relationship between stress and exercise has been limited by lack of real-time data and theoretical and statistical models. This lack may hinder efforts to promote exercise maintenance., Purpose: We test the bi-directional relationship between stress and exercise using real-time data for the average person and the variability-individual differences-in this relationship., Methods: An observational study was conducted within a single cohort randomized controlled experiment. Healthy young adults, (n = 79) who reported only intermittent exercise, completed 12 months of stress monitoring by ecological momentary assessment (at the beginning of, end of, and during the day) and continuous activity monitoring by Fitbit. A random coefficients linear mixed model was used to predict end-of-day stress from the occurrence/non-occurrence of exercise that day; a logistic mixed model was used to predict the occurrence/non-occurrence of exercise from ratings of anticipated stress. Separate regression analyses were also performed for each participant. Sensitivity analysis tested all models, restricted to the first 180 days of observation (prior to randomization)., Results: We found a significant average inverse (i.e., negative) effect of exercise on stress and of stress on exercise. There was significant between-person variability. Of N = 69, exercise was associated with a stress reduction for 15, a stress increase for 2, and no change for the remainder. We also found that an increase in anticipated stress reported the previous night or that morning was associated with a significant 20-22% decrease (OR = 0.78-0.80) in the odds of exercising that day. Of N = 69, this increase in stress reduced the likelihood of exercise for 17, increased the odds for 1, and had no effect for the remainder. We were unable to identify psychosocial factors that moderate the individual differences in these effects., Conclusions: The relationship of stress to exercise can be uni- or bi-directional and varies from person to person. A precision medicine approach may improve exercise uptake.

Background: Isolated nocturnal hypertension (INH), defined as nocturnal without daytime hypertension on ambulatory blood pressure (BP) monitoring (ABPM), has been observed to be associated with an increased risk of cardiovascular disease (CVD) events and mortality. The aim of this study was to determine the short-term reproducibility of INH., Methods: The Improving the Detection of Hypertension Study enrolled a community-based sample of adults (N = 282) in upper Manhattan without CVD, renal failure, or treated hypertension. Each participant completed two 24-hour ABPM recordings (ABPM1: first recording and ABPM2: second recording) with a mean ± SD time interval of 33 ± 17 days between recordings. Daytime hypertension was defined as mean awake systolic/diastolic BP ≥ 135/85 mm Hg; nocturnal hypertension as mean sleep systolic/diastolic BP ≥ 120/70 mm Hg; INH as nocturnal without daytime hypertension; isolated daytime hypertension (IDH) as daytime without nocturnal hypertension; day and night hypertension (DNH) as daytime and nocturnal hypertension, and any ambulatory hypertension as having daytime and/or nocturnal hypertension., Results: On ABPM1, 26 (9.2%), 21 (7.4%), and 50 (17.7%) participants had INH, IDH, and DNH, respectively. On ABPM2, 24 (8.5%), 19 (6.7%), and 54 (19.1%) had INH, IDH, and DNH, respectively. The kappa statistics were 0.21 (95% confidence interval (CI) 0.04-0.38), 0.25 (95% CI 0.06-0.44), and 0.65 (95% CI 0.53-0.77) for INH, IDH, and DNH respectively; and 0.72 (95% CI 0.63-0.81) for having any ambulatory hypertension., Conclusions: Our results suggest that INH and IDH are poorly reproducible phenotypes, and that ABPM should be primarily used to identify individuals with daytime hypertension and/or nocturnal hypertension., (© American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: The disproportionate rates of cardiovascular disease in African Americans may, in part, be due to suboptimal assessment of blood pressure (BP) with clinic BP measurements alone. To date, however, the prevalence of masked hypertension in African Americans has not been fully delineated. The purpose of this study was to evaluate masked hypertension prevalence in a large population-based sample of African Americans and examine its determinants and association with indices of target organ damage (TOD)., Methods: Clinic and 24-hour ambulatory BP monitoring were conducted in 972 African Americans enrolled in the Jackson Heart Study. Common carotid artery intima-media thickness, left ventricular mass index, and the urinary albumin:creatinine excretion ratio were evaluated as indices of TOD., Results: Masked hypertension prevalence was 25.9% in the overall sample and 34.4% in participants with normal clinic BP. All indices of TOD were significantly higher in masked hypertensives compared to sustained normotensives and were similar between masked hypertensives and sustained hypertensives. Male gender, smoking, diabetes, and antihypertensive medication use were independent determinants of masked hypertension in multivariate analyses., Conclusions: In this population-based cohort of African Americans, approximately one-third of participants with presumably normal clinic BP had masked hypertension when BP was assessed in their daily environment. Masked hypertension was accompanied by a greater degree of TOD in this cohort., (© American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Several ambulatory blood pressure monitoring (ABPM) measures have been associated with increased cardiovascular disease risk independent of clinic blood pressure (BP). African Americans have higher clinic BP compared with Whites but few data are available on racial differences in ABPM measures., Methods: We compared ABPM measures between African American (n = 178) and White (n = 103) participants at the Year 5 Coronary Artery Risk Development in Young Adults study visit. BP was measured during a study visit and the second and third measurements were averaged. ABPM was conducted over the following 24 hours., Results: Mean ± SD age of participants was 29.8 ± 3.8 years and 30.8 ± 3.5 years for African Americans and Whites, respectively. Mean daytime systolic BP (SBP) was 3.90 (SD 1.18) mm Hg higher among African Americans compared with Whites (P < 0.001) after age-gender adjustment and 1.71 (SD 1.03) mm Hg higher after multivariable adjustment including mean clinic SBP (P = 0.10). After multivariable adjustment including mean clinic SBP, nighttime SBP was 4.83 (SD 1.11) mm Hg higher among African Americans compared with Whites (P < 0.001). After multivariable adjustment, the African Americans were more likely than Whites to have nocturnal hypertension (prevalence ratio: 2.44, 95% CI: 0.99-6.05) and nondipping (prevalence ratio: 2.50, 95% CI: 1.39-4.48). The prevalence of masked hypertension among African Americans and Whites was 4.4% and 2.1%, respectively, (P = 0.49) and white coat hypertension was 3.3% and 3.9%, respectively (P = 0.99). Twenty-four hour BP variability on ABPM was higher among African Americans compared with Whites., Conclusions: These data suggest racial differences in several ABPM measures exist., (© American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Masked hypertension (MH)--nonelevated office blood pressure (BP) with elevated out-of-office BP average--conveys cardiovascular risk similar to or approaching sustained hypertension, making its detection of potential clinical importance. However, it may not be feasible or cost-effective to perform ambulatory BP monitoring (ABPM) on all patients with a nonelevated office BP. There likely exists a level of office BP below which ABPM is not warranted because the probability of MH is low., Methods: We analyzed data from 294 adults aged ≥ 30 years not on BP-lowering medication with office BP <140/90 mm Hg, all of whom underwent 24-hour ABPM. We calculated sensitivity, false-positive rate, and likelihood ratios (LRs) for the range of office BP cutoffs from 110 to 138 mm Hg systolic and from 68 to 88 mm Hg diastolic for detecting MH., Results: The systolic BP cutoff with the highest +LR for detecting MH (1.8) was 120 mm Hg, and the diastolic cutoff with the highest +LR (2.4) was 82 mm Hg. However, the systolic level of 120 mm Hg had a false-positive rate of 42%, and the diastolic level of 82 mm Hg had a sensitivity of only 39%., Conclusions: The cutoff of office BP with the best overall operating characteristics for diagnosing MH is approximately 120/82 mm Hg. However, this cutoff may have an unacceptably high false-positive rate. Clinical risk tools to identify patients with nonelevated office BP for whom ABPM should be considered will likely need to include factors in addition to office BP., (© American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: In a prior study of patients with diabetes, diastolic function was similarly impaired in masked hypertension (MHT) and sustained hypertension (SHT). We evaluated whether MHT is associated with impaired diastolic function compared with SHT and sustained normotension (NT) in the general population., Methods: From February 2005 to December 2010, 798 participants without a history of cardiovascular disease or treated hypertension, were enrolled in the Masked Hypertension Study. Participants underwent clinic blood pressure (CBP) and 24-hour ambulatory blood pressure (ABP) measurements. A 2-dimensional Doppler echocardiogram was performed to evaluate diastolic function,s cardiac structure, volume, and systolic function. The 9 CBPs obtained across 3 clinic visits and awake ABP measurements were averaged. Clinic hypertension was defined as systolic/diastolic blood pressure (SBP/DBP) ≥ 140/90 mmHg. Ambulatory hypertension was defined as awake SBP/DBP ≥ 135/85mm Hg. MHT was defined as having ambulatory but not clinic hypertension. White-coat hypertensives (n = 8) were excluded from the analysis., Results: Of the 790 participants, 116 (14.7%) participants had MHT, 37 (4.7%) participants had SHT, and 637 (80.6%) participants had NT. After age, sex, race/ethnicity, and body mass index adjustment, compared with NT, E'-velocities were significantly lower in MHT (P < 0.01) and SHT (P < 0.05), and E/E' ratios were significantly higher MHT (P < 0.05) and SHT (P < 0.05). These associations were independent of left ventricular mass. Diastolic function parameters did not significantly differ between MHT and SHT., Conclusions: Diastolic function was impaired in MHT compared with NT independent of changes in left ventricular mass.

Background: Office-blood pressure (BP) measurements alone overlook a significant number of individuals with masked-hypertension (office-BP: 120/80-139/89 mm Hg and 24-h ambulatory BP monitoring (ABPM) daytime ≥135/85 mm Hg or night-time ≥120/70 mm Hg). Diminished endothelial function contributes to the pathogenesis of hypertension. To better understand the pathophysiology involved in the increased cardiovascular (CV) disease risk associated with masked-hypertension, we estimated the occurrence, assessed the endothelial function, compared plasma levels of inflammatory markers, white blood cell count (WBC count), tumor necrosis factor-α (TNF-α), and high sensitivity C-reactive protein (hsCRP) and examined the possible relationship between endothelial function and inflammatory markers in apparently healthy prehypertensive (office-BP: 120/80-139/89 mm Hg) African Americans., Methods: Fifty African Americans who were sedentary, nondiabetic, nonsmoking, devoid of CV disease were recruited. Office-BP was measured according to JNC-7 guidelines to identify prehypertensives in whom ABPM was then assessed. Fasting plasma samples were assayed for inflammatory markers. Brachial artery flow-mediated dilation (FMD) at rest and during reactive hyperemia was measured in a subset of prehypertensives., Results: Subjects in the masked-hypertension sub-group had a higher hsCRP (P = 0.04) and diminished endothelial function (P = 0.03) compared to the true-prehypertensive sub-group (office-BP: 120/80-139/89 mm Hg and ABPM: daytime <135/85 mm Hg or night-time <120/70 mm Hg). Regression analysis showed that endothelial function was inversely related to hsCRP amongst the masked-hypertensive sub-group (R(2) = 0.160; P = 0.04)., Conclusions: Masked-hypertension was identified in 58% of African Americans which suggests that a masking phenomenon may exist in a sub-group of prehypertensives who also seem to have a diminished endothelial function that could be mediated by an elevated subclinical inflammation leading to the increased CV disease.