Exploring the direct and indirect effects of cardiovascular disease risk factors on exercise blood pressure.

OBJECTIVE: Exaggerated exercise blood pressure (BP) is independently associated with cardiovascular disease (CVD) outcomes. However, it is unknown how individual CVD risk factors may interact with one another to influence exercise BP. The aim of this study was to quantify direct and indirect associations between CVD risk factors and exercise BP, to determine what CVD risk factor/s most-strongly relate to exercise BP. METHODS: In a cross-sectional design, 660 participants (44 ± 2.6 years, 54% male) from the population-based Childhood Determinants of Adult Health Study had BP measured during low-intensity fixed-workload cycling. CVD risk factors were measured, including body composition, clinic (rest) BP, blood biomarkers, and cardiorespiratory fitness. Associations between CVD risk factors and exercise BP were assessed using linear regression, with direct and indirect pathways of association assessed via structural equation model. RESULTS: Sex, waist-to-hip ratio, fitness, and clinic BP were independently associated with exercise systolic BP (SBP), and along with age, had direct associations with exercise SBP (p < 0.05 all). Most CVD risk factors were indirectly associated with exercise SBP via a relation with clinic BP (p < 0.05 all). Clinic BP, waist-to-hip ratio, and fitness were most-strongly associated (direct and indirect association) with exercise SBP (ß[95% CI]: 9.35 [8.04, 10.67], 4.91 [2.56, 7.26], and -2.88 [-4.25, -1.51] mm Hg/SD, respectively). CONCLUSION: Many CVD risk factors are associated with exercise BP, mostly with indirect effects via clinic BP. Clinic BP, body composition, and fitness were most-strongly associated with exercise BP. These results may elucidate how lifestyle modification could be a primary strategy to decrease exaggerated exercise BP-related CVD risk.

The influence of metallothionein treatment and treadmill running exercise on disease onset and survival in SOD1G93A amyotrophic lateral sclerosis mice.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, characterised by the degeneration of motor neurons innervating skeletal muscle. The mechanisms underlying neurodegeneration in ALS are not yet fully elucidated, and with current therapeutics only able to extend lifespan by a matter of months there is a clear need for novel therapies to increase lifespan and patient quality of life. Here, we evaluated whether moderate-intensity treadmill exercise and/or treatment with metallothionein-2 (MT2), a neuroprotective protein, could improve survival, behavioural or neuropathological outcomes in SOD1G93A familial ALS mice. Six-week-old female SOD1G93A mice were allocated to one of four treatment groups: MT2 injection, i.m.; moderate treadmill exercise; neither MT2 nor exercise; or both MT2 and exercise. MT2-treated mice survived around 3% longer than vehicle-treated mice, with this mild effect reaching statistical significance in Cox proportional hazards analysis once adjusted for potential confounders. Mixed model body weight trajectories over time indicated that MT2-treated mice, with or without exercise, reached maximum body weight at a later age, suggesting a delay in disease onset of around 4% compared to saline-treated mice. Exercise alone did not significantly increase survival or delay disease onset, and neither exercise nor MT2 substantially ameliorated gait abnormalities or muscle strength loss. We conclude that neither exercise nor MT2 treatment was detrimental in female SOD1G93A mice, and further study could determine whether the mild effect of peripheral MT2 administration on disease onset and survival could be improved via direct administration of MT2 to the central nervous system.

Sex Differences in Long-Term Quality of Life Among Survivors After Stroke in the INSTRUCT.

Background and Purpose- Women are reported to have poorer health-related quality of life (HRQoL) after stroke than men, but the underlying reasons are uncertain. We investigated factors contributing to the sex differences. Methods- Individual participant data on 4288 first-ever strokes (1996-2013) were obtained from 4 high-quality population-based incidence studies from Australasia and Europe. HRQoL utility scores among survivors after stroke (range from negative scores=worse than death to 1=perfect health) were calculated from 3 scales including European Quality of Life-5 Dimensions, Short-Form 6-Dimension, and Assessment of Quality of Life at 1 year (3 studies; n=1210) and 5 years (3 studies; n=1057). Quantile regression was used to estimate the median differences in HRQoL for women compared to men with adjustment for covariates. Study factors included sociodemographics, prestroke dependency, stroke-related factors (eg, stroke severity), comorbidities, and poststroke depression. Study-specific median differences were combined into pooled estimates using random-effect meta-analysis. Results- Women had lower pooled HRQoL than men (median differenceunadjusted 1 year, -0.147; 95% CI, -0.258 to -0.036; 5 years, -0.090; 95% CI, -0.119 to -0.062). After adjustment for age, stroke severity, prestroke dependency, and depression, these pooled median differences were attenuated, more greatly at 1 year (-0.067; 95% CI, -0.111 to -0.022) than at 5 years (-0.085; 95% CI, -0.135 to -0.034). Conclusions- Women consistently exhibited poorer HRQoL after stroke than men. This was partly attributable to women's advanced age, more severe strokes, prestroke dependency, and poststroke depression, suggesting targets to reduce the differences. There was some evidence of residual differences in HRQoL between sexes but they were small and unlikely to be clinically significant.

Influence of blood pressure level and age on within-visit blood pressure variability in children and adolescents.

Blood pressure (BP) is variable in children and this could affect BP assessment, but the magnitude of within-visit BP variability (BPV) over consecutive measurements has never been investigated. This study aimed to determine the direction and magnitude of, and factors affecting, within-visit BPV in children and adolescents. BP was recorded among 3047 children (aged 12 years [95%CI 12, 13], males 52%) from the 2011-2013 Australian Health Survey. BPV was defined as the absolute difference (∆SBPABS) between the first (SBP1) and second systolic BP (SBP2) and the overall variability in three measures when available (SBPV). On average, ∆SBPABS was 6.7 mmHg (95%CI 6.3, 7.0) and SBPV was 8.2% (95%CI 7.8, 8.6). ∆SBPABS was greater with higher BP levels but lower with older age. From first to second measurements, SBP decreased in 58% (95%CI 56, 60), did not change in 10% (95%CI 9, 12), and increased in 32% (95%CI 29, 34) of the population. CONCLUSIONS: BP is highly variable in children and adolescents, with the magnitude of variability being associated with both age and BP level. SBP increases on repeat measurement in a substantial proportion of the population. The optimal protocol of BP assessment to address this increased BPV needs to be determined. What is Known: • Diagnosis of elevated blood pressure (BP) is based on strict probabilistic criteria, the difference between the 90th (pre-hypertension) and 95th (hypertension) percentiles only being 3-4 mmHg. • BP variability could affect BP classification among children and adolescents. What is New: • The magnitude of BP change among children and adolescents is highly affected by BP level and age. • BP does not always drop on consecutive measurements, and evidence-based BP assessment protocols should be established to avoid misdiagnosis of hypertension.

Fruit and vegetable consumption in Vietnam, and the use of a 'standard serving' size to measure intake.

The aims of the present study were to provide nationally representative data on fruit and vegetable consumption in Vietnam, and to assess the accuracy of the reported numbers of 'standard servings' consumed. Data analysed were from a multi-stage stratified cluster survey of 14 706 participants (46·5 % males, response proportion 64·1 %) aged 25-64 years in Vietnam. Measurements were made in accordance with the WHO STEPwise approach to surveillance of non-communicable diseases (STEPS) protocols. Approximately 80 % of Vietnamese people reported having less than five servings of fruit and vegetables daily in a typical week. Fruit and vegetable intake reported in 'standard serving' sizes was positively correlated with levels of education completed and household income (P<0·001 for trend). The correlations between summary values for each province reflect some known demographic, geographical and climatic characteristics of the country. For example, provinces at higher latitude had higher mean servings of vegetables (r 0·90), and provinces with higher proportions of urban population had higher mean servings of fruit (r 0·40). In conclusion, about eight in ten Vietnamese people aged 25-64 years did not meet WHO recommendations for daily consumption of at least five servings of fruit and vegetables. On the basis of the consistency of the data collected with other estimates and with physical and demographic characteristics of the country, the WHO STEPS instrument has construct validity for measuring fruit and vegetable intake, but with two issues identified. The issues were seasonal variation in reporting and a limitation on the usefulness of the information for associative analyses.

Roles of nonclinical and clinical data in prediction of 30-day rehospitalization or death among heart failure patients.

BACKGROUND: Selecting heart failure (HF) patients for intensive management to reduce readmissions requires effective targeting. However, available prediction scores are only modestly effective. We sought to develop a prediction score for 30-day all-cause rehospitalization or death in HF with the use of nonclinical and clinical data. METHODS AND RESULTS: This statewide data linkage included all patients who survived their 1st HF admission (with either reduced or preserved ejection fraction) to a Tasmanian public hospital during 2009-2012. Nonclinical data (n = 1,537; 49.5% men, median age 80 y) included administrative, socioeconomic, and geomapping data. Clinical data before discharge were available from 977 patients. Prediction models were developed and internally and externally validated. Within 30 days of discharge, 390 patients (25.4%) died or were rehospitalized. The nonclinical model (length of hospital stay, age, living alone, discharge during winter, remoteness index, comorbidities, and sex) had fair discrimination (C-statistic 0.66 [95% confidence interval (CI) 0.63-0.69]). Clinical data (blood urea nitrogen, New York Heart Association functional class, albumin, heart rate, respiratory rate, diuretic use, angiotensin-converting enzyme inhibitor use, arrhythmia, and troponin) provided better discrimination (C-statistic 0.72 [95% CI 0.68-0.76]). Combining both data sources best predicted 30-day rehospitalization or death (C-statistic 0.76 [95% CI 0.72-0.80]). CONCLUSIONS: Clinical data are stronger predictors than nonclinical data, but combining both best predicts 30-day rehospitalization or death among HF patients.

Sex Differences in Causes of Death After Stroke: Evidence from a National, Prospective Registry.

Background: We examined sex differences in cause of death and cause-specific excess mortality after stroke. Materials and Methods: First-ever strokes (2010-2013; 35 hospitals) participating in the Australian Stroke Clinical Registry were linked to national death registrations and other administrative datasets. One-year cause-specific mortality was categorized as stroke, ischemic heart disease, other cardiovascular disease (CVD; e.g., hypertension), cancer, and other. Specific hazard ratios (sHRs) of death for women compared to men were estimated using competing risk models, with adjustment for factors differing by sex (e.g., age and stroke severity). Age- and sex-specific mortality rates expected in the general population were derived from national data. Standardized mortality ratios (SMRs; observed/expected deaths) were estimated for cause-specific mortality by sex after age standardization. Results: Among 9,441 cases (46% women), women were 7 years older than men, had more severe strokes, and received similar patterns of suboptimal secondary prevention medications at discharge. Women had greater mortality associated with stroke (sHRunadjusted 1.65) and other CVD (sHRunadjusted 1.65), which was related to age and stroke severity rather than other factors. Compared to population norms, those surviving to 30 days had eight-fold increased mortality from stroke (primary/recurrent) events irrespective of sex (SMRage-standardised women 8.8; men 8.3). Excess mortality from other CVD was greater in women (SMRage-standardised 3.6 vs. men 2.8; p = 0.026). Conclusions: Cause-specific mortality after first-ever stroke differs by sex. The greater death rate attributed to stroke/other CVD in women was mostly explained by age and stroke severity. Greater implementation of secondary stroke prevention is relevant to both sexes.

Sex Differences in Care and Long-Term Mortality After Stroke: Australian Stroke Clinical Registry.

Introduction: There is some evidence that women receive evidence-based care less often than men, but how this influences long-term mortality after stroke is unclear. We explored this issue using data from a national stroke registry. Materials and Methods: Data are first-ever hospitalized strokes (2010-2014) in the Australian Stroke Clinical Registry from 39 hospitals linked to the national death registrations. Multilevel Poisson regression was used to estimate the women:men mortality rate ratio (MRR), with adjustment for sociodemographics, stroke severity, and processes of care (stroke unit care, intravenous thrombolysis, antihypertensive agent[s], and discharge care plan). Results: Among 14,118 events (46% females), women were 7 years older and had greater baseline severity compared to men (29% vs. 37%; p < 0.001), but there were no differences in the four processes of care available across hospitals. In the whole cohort, 1-year mortality was greater in women than men (MRRunadjusted 1.44, 95% confidence interval [CI] 1.34-1.54). However, there were no differences after adjusting for age and stroke severity (MRRadjusted 1.03, 95% CI 0.95-1.10). In analyses of additional processes from Queensland hospitals (n = 5224), women were less often administered aspirin ≤48 hours (61% vs. men 69%, p < 0.015). In Queensland hospitals, there were no statistically significant sex differences in 1-year mortality after adjusting for age, stroke severity, and early administration of aspirin. Conclusion: Greater mortality in women can be explained by differences in age and stroke severity. This highlights the importance of better management of risk factors in the elderly and, potentially, the need for greater access to early aspirin for women with stroke.

Sex Differences in Severity of Stroke in the INSTRUCT Study: a Meta-Analysis of Individual Participant Data.

Background Women have worse outcomes after stroke than men, and this may be partly explained by stroke severity. We examined factors contributing to sex differences in severity of acute stroke assessed by the National Institutes of Health Stroke Scale. Methods and Results We pooled individual participant data with National Institutes of Health Stroke Scale assessment (N=6343) from 8 population-based stroke incidence studies (1996-2014), forming part of INSTRUCT (International Stroke Outcomes Study). Information on sociodemographics, stroke-related clinical factors, comorbidities, and pre-stroke function were obtained. Within each study, relative risk regression using log-binominal modeling was used to estimate the female:male relative risk ( RR ) of more severe stroke (National Institutes of Health Stroke Scale>7) stratified by stroke type (ischemic stroke and intracerebral hemorrhage). Study-specific unadjusted and adjusted RR s, controlling for confounding variables, were pooled using random-effects meta-analysis. National Institutes of Health Stroke Scale data were recorded in 5326 (96%) of 5570 cases with ischemic stroke and 773 (90%) of 855 participants with intracerebral hemorrhage. The pooled unadjusted female:male RR for severe ischemic stroke was 1.35 (95% CI 1.24-1.46). The sex difference in severity was attenuated after adjustment for age, pre-stroke dependency, and atrial fibrillation but remained statistically significant (pooled RR adjusted 1.20, 95% CI 1.10-1.30). There was no sex difference in severity for intracerebral hemorrhage ( RR crude 1.08, 95% CI 0.97-1.21; RR adjusted 1.08, 95% CI 0.96-1.20). Conclusions Although women presented with more severe ischemic stroke than men, much although not all of the difference was explained by pre-stroke factors. Sex differences could potentially be ameliorated by strategies to improve pre-stroke health in the elderly, the majority of whom are women. Further research on the potential biological origin of sex differences in stroke severity may also be warranted.

Misclassification of blood pressure of Vietnamese adults when only a single measurement is used.

A single clinic measurement of blood pressure (BP) may be common in low- and middle-income countries because of limited medical resources. This study aimed to examine the potential misclassification error when only one BP measurement is used. Participants (n = 14,706, 53.5% females) aged 25-64 years were selected by multistage stratified cluster sampling from eight provinces, each representing one of the eight geographical regions of Vietnam. Measurements were made using the World Health Organization STEPS protocols. Data were analyzed using complex survey methods. For systolic BP, 62.7% had a higher first reading whereas 30.0% had a lower first reading, and 27.3% had a reduction of at least 5 mmHg whereas 9.6% had an increase of at least 5 mmHg. Irrespective of direction of change, increased variability in BP was associated with greater age, urban living, greater body size and fatness, reduced physical activity levels, elevated glucose, and raised total cholesterol. These measurement variations would lead to substantial misclassification in diagnosis of hypertension based on a single reading because almost 20% of subjects would receive a different diagnosis based on the mean of two readings.

Factors contributing to sex differences in functional outcomes and participation after stroke.

OBJECTIVE: To examine factors contributing to the sex differences in functional outcomes and participation restriction after stroke. METHODS: Individual participant data on long-term functional outcome or participation restriction (i.e., handicap) were obtained from 11 stroke incidence studies (1993-2014). Multivariable log-binomial regression was used to estimate the female:male relative risk (RR) of poor functional outcome (modified Rankin Scale score >2 or Barthel Index score <20) at 1 year (10 studies, n = 4,852) and 5 years (7 studies, n = 2,226). Multivariable linear regression was used to compare the mean difference (MD) in participation restriction by use of the London Handicap Scale (range 0-100 with lower scores indicating poorer outcome) for women compared to men at 5 years (2 studies, n = 617). For each outcome, study-specific estimates adjusted for confounding factors (e.g., sociodemographics, stroke-related factors) were combined with the use of random-effects meta-analysis. RESULTS: In unadjusted analyses, women experienced worse functional outcomes after stroke than men (1 year: pooled RRunadjusted 1.32, 95% confidence interval [CI] 1.18-1.48; 5 years: RRunadjusted 1.31, 95% CI 1.16-1.47). However, this difference was greatly attenuated after adjustment for age, prestroke dependency, and stroke severity (1 year: RRadjusted 1.08, 95% CI 0.97-1.20; 5 years: RRadjusted 1.05, 95% CI 0.94-1.18). Women also had greater participation restriction than men (pooled MDunadjusted -5.55, 95% CI -8.47 to -2.63), but this difference was again attenuated after adjustment for the aforementioned factors (MDadjusted -2.48, 95% CI -4.99 to 0.03). CONCLUSIONS: Worse outcomes after stroke among women were explained mostly by age, stroke severity, and prestroke dependency, suggesting these potential targets to improve the outcomes after stroke in women.

Age-dependent changes in blood pressure over consecutive office measurements: impact on hypertension diagnosis and implications for international guidelines.

OBJECTIVES: Based on anecdotal belief that blood pressure (BP) drops over consecutive measurements, guidelines recommend discarding the first BP reading (Canadian Hypertension Education Program guidelines) or take only one reading if SBP less than 140 mmHg (National Institute for Health and Care Excellence). However, the extent to which SBP fluctuations affect BP classification as well as the potential effect of age are unknown. We sought to assess the change in SBP classification over consecutive measurements following different guidelines, among younger (<50 years) and older individuals (≥50 years). Furthermore, we aimed to investigate the direction of the change in SBP over consecutive measurements (increase or decrease) and the impact of age on SBP differences. METHODS: BP was measured among 20 716 adults from a general population. SBP was classified using the first reading (normal SBP or hypertension) and compared with the average SBP using different guideline protocols (reclassification). RESULTS: Reclassification from normal SBP to hypertension was greatest with Canadian Hypertension Education Program guidelines (3% younger, 12% older individuals) and reclassification from hypertension to normal SBP was greatest with National Institute for Health and Care Excellence guidelines (70% younger, 44% older individuals). SBP increased between the first two measures in 37%, decreased in 56% and did not change in 7% of the population. Age had a strong interaction with SBP level (P < 0.0001) so that younger individuals exhibited greater SBP differences over repeated measures. CONCLUSION: This study highlights the need for an improvement in the evidence-base regarding the best way to assess office BP for correct hypertension diagnosis.

Sex Differences in Long-Term Mortality After Stroke in the INSTRUCT (INternational STRoke oUtComes sTudy): A Meta-Analysis of Individual Participant Data.

BACKGROUND: Women are reported to have greater mortality after stroke than men, but the reasons are uncertain. We examined sex differences in mortality at 1 and 5 years after stroke and identified factors contributing to these differences. METHODS AND RESULTS: Individual participant data for incident strokes were obtained from 13 population-based incidence studies conducted in Europe, Australasia, South America, and the Caribbean between 1987 and 2013. Data on sociodemographics, stroke-related factors, prestroke health, and 1- and 5-year survival were obtained. Poisson modeling was used to estimate the mortality rate ratio (MRR) for women compared with men at 1 year (13 studies) and 5 years (8 studies) after stroke. Study-specific adjusted MRRs were pooled to create a summary estimate using random-effects meta-analysis. Overall, 16 957 participants with first-ever stroke followed up at 1 year and 13 216 followed up to 5 years were included. Crude pooled mortality was greater for women than men at 1 year (MRR 1.35; 95% confidence interval, 1.24-1.47) and 5 years (MRR 1.24; 95% confidence interval, 1.12-1.38). However, these pooled sex differences were reversed after adjustment for confounding factors (1 year MRR, 0.81; 95% confidence interval, 0.72-0.92 and 5-year MRR, 0.76; 95% confidence interval, 0.65-0.89). Confounding factors included age, prestroke functional limitations, stroke severity, and history of atrial fibrillation. CONCLUSIONS: Greater mortality in women is mostly because of age but also stroke severity, atrial fibrillation, and prestroke functional limitations. Lower survival after stroke among the elderly is inevitable, but there may be opportunities for intervention, including better access to evidence-based care for cardiovascular and general health.

Blood Pressure Variability and Prediction of Target Organ Damage in Patients With Uncomplicated Hypertension.

BACKGROUND: The average of multiple blood pressure (BP) readings (mean BP) independently predicts target organ damage (TOD). Observational studies have also shown an independent relationship between BP variability (BPV) and TOD, but there is limited longitudinal data. This study aimed to determine the effects of changes in mean BP levels compared with BPV on left ventricular mass index (LVMI) and aortic pulse wave velocity (aPWV). METHODS: Mean BP levels (research-protocol clinic BP (clinic BP), 24-hour ambulatory BP, and 7-day home BP) and BPV were assessed in 286 patients with uncomplicated hypertension (mean age 64±8 SD years, 53% women) over 12 months. Reading-to-reading BPV (from 24-hour ambulatory BP) and day-to-day BPV (from 7-day home BP) were assessed at baseline and 12 months, and visit-to-visit BPV (clinic BP) was assessed from 5 visits over 12 months. LVMI was measured by 3D echocardiography and aPWV with applanation tonometry. RESULTS: The strongest predictors of the changes in LVMI (ΔLVMI) were the changes in mean 24-hour systolic BPs (SBPs) (P < 0.02). Similarly, the strongest predictors of the changes in aPWV (ΔaPWV) were the changes in mean 24-hour ambulatory SBPs (P < 0.01) and the changes in mean clinic SBP (P < 0.001). However, none of the changes in BPV were independently associated with ΔLVMI or ΔaPWV (P > 0.05 for all). CONCLUSIONS: Changes in mean BP levels, but not BPV, were most relevant to changes in TOD in patients with uncomplicated hypertension. Thus, from this point of view, BPV appears to have limited clinical utility in this patient population.

Longitudinal Relationships Between Cognitive Decline and Gait Slowing: The Tasmanian Study of Cognition and Gait.

BACKGROUND: Gait slowing and cognitive decline are both common in older people. Although cross-sectionally related, the longitudinal associations between specific cognitive functions and gait speed are less well understood. We aimed to determine whether decline in specific cognitive domains are associated with change in gait speed. METHODS: Participants aged 60-85, randomly selected from the electoral roll, were assessed twice over 3 years. Gait speed was obtained using the GAITRite walkway. Raw scores from a cognitive battery were subjected to principal component analyses deriving summary domains of executive function, processing speed, memory, and visuospatial ability. Multivariable linear regression was used to examine the associations between change in each cognitive domain and change in gait speed, adjusting for covariates and stratifying for the presence of baseline cognitive impairment. RESULTS: Mean age at baseline was 71.1 years (SD = 6.7) and 56% (159/284) were men. Mean follow-up was 2.55 (0.47) years. Decline in executive function, but not other cognitive domains (p > .05), was associated with decline in gait speed, cm/s (ß = -3.55, 95% CI = -5.49, -1.61; p < .001), both in the presence and absence of baseline cognitive impairment. Stronger associations were seen for those with baseline multiple domain cognitive impairment (ß = -6.38, 95% CI = -12.49, -0.27) and nonamnestic single-domain cognitive impairment (ß = -7.74, 95% CI = -14.76, -0.72). CONCLUSION: Decline in nonamnestic function (specifically executive function) was associated with decline in gait speed irrespective of the presence of baseline cognitive impairment. Strategies to improve or maintain executive function may prevent gait slowing.

Vigorous physical activity and carotid distensibility in young and mid-aged adults.

Although physical activity (PA) improves arterial distensibility, it is unclear which type of activity is most beneficial. We aimed to examine the association of different types of PA with carotid distensibility (CD) and the mechanisms involved. Data included 4503 Australians and Finns aged 26-45 years. Physical activity was measured by pedometers and was self-reported. CD was measured using ultrasound. Other measurements included resting heart rate (RHR), cardiorespiratory fitness (CRF), blood pressure, biomarkers and anthropometry. Steps/day were correlated with RHR (Australian men r = -0.10, women r = - 0.14; Finnish men r = -0.15, women r = -0.11; P<0.01), CRF and biochemical markers, but not with CD. Self-reported vigorous leisure-time activity was more strongly correlated with RHR (Australian men r = -0.23, women r = -0.19; Finnish men r = -0.20, women r = -0.13; P < 0.001) and CRF, and was correlated with CD (Australian men r = 0.07; Finnish men r = 0.07, women r = 0.08; P < 0.05). This relationship of vigorous leisure-time activity with CD was mediated by RHR independently of potential confounders. In summary, vigorous leisure-time PA but not total or less intensive PA was associated with arterial distensibility in young to mid-aged adults. Promotion of vigorous PA is therefore recommended among this population. RHR was a key intermediary factor explaining the relationship between vigorous PA and arterial distensibility.

The cross-sectional association of sitting time with carotid artery stiffness in young adults.

OBJECTIVES: Physical activity is negatively associated with arterial stiffness. However, the relationship between sedentary behaviour and arterial stiffness is poorly understood. In this study, we aimed to investigate the association of sedentary behaviour with arterial stiffness among young adults. DESIGN: Cross-sectional. SETTING: 34 study clinics across Australia during 2004-2006. PARTICIPANTS: 2328 participants (49.4% male) aged 26-36 years who were followed up from a nationally representative sample of Australian schoolchildren in 1985. MEASUREMENTS: Arterial stiffness was measured by carotid ultrasound. Sitting time per weekday and weekend day, and physical activity were self-reported by questionnaire. Cardiorespiratory fitness was estimated as physical work capacity at a heart rate of 170 bpm. Anthropometry, blood pressure, resting heart rate and blood biochemistry were measured. Potential confounders, including strength training, education, smoking, diet, alcohol consumption and parity, were self-reported. Rank correlation was used for analysis. RESULTS: Sitting time per weekend day, but not per weekday, was correlated with arterial stiffness (males r=0.11 p<0.01, females r=0.08, p<0.05) and cardiorespiratory fitness (males r = -0.14, females r = -0.08, p<0.05), and also with fatness and resting heart rate. One additional hour of sitting per weekend day was associated with 5.6% (males p=0.046) and 8.6% (females p=0.05) higher risk of having metabolic syndrome. These associations were independent of physical activity and other potential confounders. The association of sitting time per weekend day with arterial stiffness was not mediated by resting heart rate, fatness or metabolic syndrome. CONCLUSIONS: Our study demonstrates a positive association of sitting time with arterial stiffness. The greater role of sitting time per weekend day in prediction of arterial stiffness and cardiometabolic risk than that of sitting time per weekday may be due to better reflection of discretionary sitting behaviour.

Resting heart rate and the association of physical fitness with carotid artery stiffness.

BACKGROUND: Physical fitness is known to influence arterial stiffness. Resting heart rate is reduced by exercise and positively associated with arterial stiffness. This study aimed to investigate the role of resting heart rate in the relationship of physical fitness with arterial stiffness. METHODS: Subjects were 2,328 young adults from the Childhood Determinants of Adult Health study. Cardiorespiratory fitness was estimated as physical work capacity at a heart rate of 170 bpm. Muscular strength was estimated by hand-grip (both sides), shoulder (pull and push), and leg strength. Arterial stiffness was measured using carotid ultrasound. RESULTS: Arterial stiffness was negatively associated with cardiorespiratory fitness (men P < 0.001; women P = 0.002), and positively associated with muscular strength in women (P = 0.002) but not in men. Resting heart rate was positively associated with arterial stiffness (P < 0.001 both men and women). Adjustment for resting heart rate reduced the inverse association of arterial stiffness with cardiorespiratory fitness by 93.7% (men) and 67.6% (women) but substantially increased the positive association of arterial stiffness with muscular strength among women and revealed a positive association of arterial stiffness with muscular strength among men. These findings were independent of body size, blood pressure, biochemical markers, socioeconomic status, smoking, and alcohol consumption. CONCLUSIONS: Our findings attribute a key intermediary role for resting heart rate in the relationship between fitness and arterial stiffness, whereby higher cardiorespiratory fitness may reduce arterial stiffness mainly through resting heart rate, and higher muscular strength might have deleterious effects on arterial stiffness that are partially offset by lower resting heart rate.

Blood pressure and body mass index: a comparison of the associations in the Caucasian and Asian populations.

A strong association between blood pressure (BP) and body mass index (BMI) has been observed in developed and developing countries. Whether there are differences in these associations between Caucasians and Asians remains unknown. Our objective was to compare the associations of BP with fatness measures in the Caucasian and Asian samples. The study used data from two population-based cross-sectional studies conducted using similar methodology: a survey in Australia in 1998-1999 (n = 832 adults aged 25-64 years; 47% male) and a survey in Vietnam in 2005 (n = 1978 adults aged 25-64 years; 46% male). Participants completed questionnaires and attended clinics for physical measurements including BP and anthropometry. Linear regression was used for analysis. Independent of age, there were strong associations between BP indices and BMI in each sample, but the patterns of associations were different. Among Caucasians, pulse pressure (PP) increased with increasing BMI because the slope of systolic pressure with BMI exceeded the slope of diastolic pressure with BMI (P<0.001 for both sexes). In contrast, among Asians, PP decreased with increasing BMI. Associations between BMI and BP are different between Caucasian and Asian populations. Among Asians, the stronger association of increasing BMI and diastolic BP, but not PP, suggests a different pathophysiology related to hypertension.