Physical Activity, Sedentary Behavior, and Long-Term Changes in Aortic Stiffness: The Whitehall II Study

Physical Fitness and Aortic Stiffness Explain the Reduced Cognitive Performance Associated with Increasing Age in Older People

BACKGROUND

Greater physical fitness is associated with reduced rates of cognitive decline in older people; however, the mechanisms by which this occurs are still unclear. One potential mechanism is aortic stiffness, with increased stiffness resulting in higher pulsatile pressures reaching the brain and possibly causing progressive micro-damage. There is limited evidence that those who regularly exercise may have lower aortic stiffness.

OBJECTIVE

To investigate whether greater fitness and lower aortic stiffness predict better cognitive performance in older people and, if so, whether aortic stiffness mediates the relationship between fitness and cognition.

METHODS

Residents of independent living facilities, aged 60-90, participated in the study (N = 102). Primary measures included a computerized cognitive assessment battery, pulse wave velocity analysis to measure aortic stiffness, and the Six-Minute Walk test to assess fitness. Based on hierarchical regression analyses, structural equation modelling was used to test the mediation hypothesis.

RESULTS

Both fitness and aortic stiffness independently predicted Spatial Working Memory (SWM) performance, however no mediating relationship was found. Additionally, the derived structural equation model shows that, in conjunction with BMI and sex, fitness and aortic stiffness explain 33% of the overall variation in SWM, with age no longer directly predicting any variation.

CONCLUSIONS

Greater fitness and lower aortic stiffness both independently predict better SWM in older people. The strong effect of age on cognitive performance is totally mediated by fitness and aortic stiffness. This suggests that addressing both physical fitness and aortic stiffness may be important to reduce the rate of age associated cognitive decline.

Impact of Prolonged Sitting on Peripheral and Central Vascular Health

Prolonged, uninterrupted sitting negatively impacts markers of peripheral vascular health, particularly, vasodilatory function of leg arteries. Whether sitting can similarly impact measures of central vascular health, as well as overall leg vasoreactivity (i.e., vasodilatory and vasoconstrictor function) remains unknown. To address this, measurements were made in relatively healthy participants (i.e., free of overt disease; n = 20, age = 26 ± 7; body mass index = 30 ± 7 kg/m²; 7 female) pre, during and post 3 hours of uninterrupted sitting. Measures of central vascular health included arterial wave reflection (augmentation index and Reflection Magnitude-RM%) and aortic vascular stiffness (aortic pulse wave velocity). Local vasoreactivity of the distal, posterior tibial artery was measured using flow-mediated dilation-FMD, coupled with low-flow mediated constriction, and microvascular function was assessed through the total hyperemic blood velocity (area-under-curve) response during FMD. After sitting, there was a significant increase in aortic pulse wave velocity (pre sit = 5.7 ± 0.3 vs post sit = 6.1 ± 0.3 m/s; p = 0.009, d = 0.36), whereas, augmentation index decreased (pre sit = 13 ± 3 vs post sit = 3 ± 1%; p < 0.001, d = 0.71). Albeit a moderate effect for decrease, RM% was not significantly altered during sitting (p = 0.13, d = 0.3). Vasodilatory (i.e., FMD pre sit = 0.5 ± 0.04 vs post sit = 0.3 ± 0.04 mm; p = 0.014, d = 0.29) and microvascular function (i.e., Microvascular area-under-curve: pre sit = 2,196 ± 333 vs 1,157±172 AU; p = 0.003, d = 0.31) decreased, but vasoconstrictor function (low-flow mediated constriction; p = 0.85, d = 0.005) was unaffected by sitting. In conclusion, these data demonstrate that a prolonged bout of uninterrupted sitting negatively impacts markers of peripheral and central vascular health in relatively healthy adults.

Neurovascular coupling during cognitive activity in adults with controlled hypertension

Hypertension, even when controlled, may accelerate arterial stiffening and impair the ability of the cerebrovasculature to increase blood flow to support neural activity, i.e., neurovascular coupling (NVC). Optimal NVC depends on continuous, nonpulsatile flow, which is partially determined by extra- and intracranial vessel function. We sought to compare extra- and intracranial hemodynamics during cognitive activity (Stroop task) in 30 middle-aged, well-controlled medicated hypertensive and 30 age-, sex-, and body mass index (BMI)-matched nonhypertensive adults (56 ± 6 years, 28.2 ± 2.9 kg/m2 BMI; 32 men). Aortic and carotid (single point) pulse wave velocity (PWV) were assessed via tonometry and ultrasound, respectively. Carotid and middle cerebral artery (MCA) blood velocity pulsatility were measured via ultrasound and Doppler. Prefrontal cortex (PFC) oxygenation was measured via tissue saturation index (TSI) using near-infrared spectroscopy. Accuracy and reaction times were computed to assess cognitive performance. Stroop performance was similar between groups ( P > 0.01). Aortic and carotid PWV increased, carotid flow pulsatility decreased ( P < 0.01), and MCA flow pulsatility and PFC TSI were maintained during Stroop ( P > 0.01). Our findings indicate that middle-age adults with medically controlled hypertension and adults without hypertension demonstrate similar intra- and extracranial cerebrovascular reactivity during cognitive engagement. Despite increases in large artery stiffness, middle-aged adults with controlled hypertension and without hypertension exhibit reductions in extracranial flow pulsatility during cognitive engagement that may be part of a concerted cerebrovascular response to support downstream cerebral oxygenation and overall NVC.

NEW & NOTEWORTHY Hypertension is associated with accelerated arterial stiffening, which may alter extra- and intracranial vascular reactivity during cognitive activity and impair neurovascular coupling. Middle-aged adults with medicated hypertension exhibit similar neurovascular coupling and extra-/intracranial vascular reactivity during sustained cognitive activity. Extracranial modulation of central hemodynamics may be an important component of optimal neurovascular coupling.

Determinants of Vascular Age: An Epidemiological Perspective

BACKGROUND

Vascular age is an emerging health indicator and predictor of end-organ damage to the heart, brain, and kidney. Although there have been many review publications concerning risk factors for vascular aging, most include cross-sectional epidemiological studies, limiting inferences about temporality. There is a need for a review of longitudinal epidemiological studies with repeated measures of vascular structure and function to allow for a systematic examination of determinants of vascular age and the association of vascular aging with outcomes.

CONTENT

Arterial stiffness is the most frequently used measure of vascular aging. We report here results of an extensive literature review of longitudinal cohort studies with repeated measures of arterial stiffness to characterize determinants of vascular age. Additionally, we summarize population-based studies that have focused on the association of arterial stiffness with end-organ damage and adverse cardiovascular outcomes.

SUMMARY

Changes in arterial stiffness are evident in early childhood. In adults, arterial stiffness has been observed to progress at the average rate of 0.2 to 0.7 m/s for every 5 years of life. The state of the science is limited by the small number of studies with repeated measures of arterial stiffness and determinants of arterial stiffness progression, as well as limited studies in children and diverse race/ethnic groups. Several extant studies suggest that beyond age, cardiometabolic risk factors and adverse lifestyle behaviors contribute to arterial stiffening. Therefore, arterial stiffness is important in the assessment of healthy vascular aging and a possible target for the prevention of subclinical and clinical disease.

Habitual physical activity and central artery stiffening in older adults: the Atherosclerosis Risk in Communities study

INTRODUCTION

Regular physical activity appears to attenuate or even reverse age-related arterial stiffening. Yet, it is not clear if the reduced stiffening associated with habitual physical activity is also observed in community-dwelling older adults.

METHODS

Among 3893 older adults in a prospective cohort study, we associated physical activity with measures of central arterial stiffness (via carotid-femoral pulse wave velocity or cfPWV) and pressure pulsatility (via central pulse pressure or cPP). We also examined the association of long-term habitual physical activity, measured as persistence in physical activity levels from mid-life to late-life, with cfPWV and cPP among 1747 participants.

RESULTS

The adjusted mean difference in cfPWV was lower, reflecting less arterial stiffness, for those with moderate (ß = -0.30 m/s) or high (ß = -0.38 m/s) physical activity compared with no physical activity. The adjusted mean difference in cPP was also lower for those with high (ß = -2.49 mmHg) physical activity, relative to no physical activity. Stronger effect estimates were observed among those with persistent physical activity from mid-life to late-life.

CONCLUSION

Higher physical activity in late-life, and habitual physical activity from mid-life to late-life, is associated with lower central arterial stiffness and pressure pulsatility in a large population-based sample of community-dwelling older adults.

Physical Activity, Sedentary Time, and Cardiovascular Disease Biomarkers at Age 60 to 64 Years

Background We examined associations of objectively measured physical activity ( PA ) and sedentary time with cardiovascular disease biomarkers at age 60 to 64 years. This included investigation of sex differences and the extent to which associations may be mediated by adiposity. Methods and Results Participants were 795 men and 827 women aged 60 to 64 years from the Medical Research Council National Survey of Health and Development. Combined heart rate and movement sensors worn for 5 consecutive days were used to derive overall PA energy expenditure, kJ /kg per day) and time spent sedentary (<1.5 metabolic equivalent of tasks), in light PA (1.5-3 metabolic equivalent of tasks) and moderate-to-vigorous intensity PA (>3 metabolic equivalent of tasks). Linear regression models were used to relate each PA parameter to inflammatory (C-reactive protein, interleukin-6), endothelial (tissue-plasminogen activator, E-selectin) and adipokine (leptin, adiponectin) markers extracted from fasting blood samples. Greater time in light PA and moderate-to-vigorous intensity PA and less sedentary time were associated with more favorable biomarker levels. For C-reactive protein, interleukin-6, and leptin, these differences were greater among women than men. For example, % differences (95% confidence intervals) in leptin for men and women per SD increases in sedentary time: 7.9 (2.7, 13.0) and 20.6 (15.3, 25.8); light intensity PA : -3.8 (-8.9, 12.7) and -17.7 (-23.1, -12.4), moderate-to-vigorous intensity PA : -12.9 (-17.9, -8.0) and -18.3 (-23.4, -13.1). Fat mass mediated a greater proportion of these associations in women than men. Conclusions Greater light PA and moderate-to-vigorous intensity PA and less sedentary time in early old age were associated with more favorable cardiovascular biomarker profiles. Fat mass partially mediated these associations but more strongly in women than men, which explained sex differences.

Quantification of aortic stiffness in stroke patients using 4D flow MRI in comparison with transesophageal echocardiography

To quantify stiffness of the descending aorta (DAo) in stroke patients using 4D flow MRI and compare results with transesophageal echocardiography (TEE). 48 acute stroke patients undergoing 4D flow MRI and TEE were included. Intima-media-thickness (IMT) was measured in the DAo and the aorta was scrutinized for atherosclerotic plaques using TEE. Stiffness of the DAo was determined by (a) 4D flow MRI at 3 T by calculating pulse wave velocity (PWV) and by (b) TEE calculating arterial strain, stiffness index, and distensibility coefficient. Mean IMT was 1.43 ± 1.75. 7 (14.6%) subjects had no sign of atherosclerosis, 10 (20.8%) had IMT-thickening or plaques < 4 mm, and 31 (66.7%) had at least one large and/or complex plaque in the aorta. Increased IMT significantly correlated (p < 0.001) with increased DAo stiffness in MRI (PWV r = 0.66) and in TEE (strain r = 0.57, stiffness index r = 0.64, distensibility coefficient r = 0.57). Patients with at least IMT-thickening had significantly higher stiffness values compared to patients without atherosclerosis. However, no difference was observed between patients with plaques < 4 mm and patients with plaques ≥ 4 mm. PWV and TEE parameters of stiffness correlated significantly [strain (r = - 0.36; p = 0.011), stiffness index (r = 0.51; p = 0.002), and distensibility coefficient (r = - 0.59; p < 0.001)]. 4D flow MRI and TEE-based parameters of aortic stiffness were associated with markers of atherosclerosis such as IMT-thickness and presence of plaques. We believe that 4D flow MRI is a promising tool for future studies of aortic atherosclerosis, due to its longer coverage of the aorta and non-invasiveness.

Cardiorespiratory fitness and age-related arterial stiffness in women with systemic lupus erythematosus

BACKGROUND

The aim of this study was twofold: (i) to examine the association of cardiorespiratory fitness with arterial stiffness in women with systemic lupus erythematosus; (ii) to assess the potential interaction of cardiorespiratory fitness with age on arterial stiffness in this population.

MATERIALS AND METHODS

A total of 49 women with systemic lupus erythematosus (mean age 41.3 [standard deviation 13.8] years) and clinical stability during the previous 6 months were included in the study. Arterial stiffness was assessed through pulse wave velocity (Mobil-O-Graph® 24 hours pulse wave velocity monitor). Cardiorespiratory fitness was estimated with the Siconolfi step test and the 6-minute walk test.

RESULTS

Cardiorespiratory fitness was inversely associated with pulse wave velocity in crude analyses (P < .05), although this relationship was attenuated when age and other cardiovascular risk factors were controlled. There was a cardiorespiratory fitness × age interaction effect on pulse wave velocity, regardless of the test used to estimate cardiorespiratory fitness (P < .001 for the Siconolfi step test; P = .005 for the 6-minute walk test), indicating that higher cardiorespiratory fitness was associated with a lower increase in pulse wave velocity per each year increase in age.

CONCLUSIONS

The results of this study suggest that cardiorespiratory fitness might attenuate the age-related arterial stiffening in women with systemic lupus erythematosus and might thus contribute to the primary prevention of cardiovascular disease in this population. As the cross-sectional design precludes establishing causal relationships, future clinical trials should confirm or contrast these findings.

Superior Effects of High-Intensity Interval Training vs. Moderate Continuous Training on Arterial Stiffness in Episodic Migraine: A Randomized Controlled Trial

Background: Migraine is associated with increased cardiovascular risk and vascular dysfunction. Since aerobic exercise can reduce cardiovascular risk, the present randomized controlled trail aimed at investigating the effects of high-intensity interval training (HIT) vs. moderate continuous exercise training (MCT) on arterial stiffness in migraine patients.

Methods: Forty-eight episodic migraineurs were initially enrolled in the study. 37 patients [female: 30; age: 37 (SD: 10); BMI: 23.1 (5.2); Migraine days per month: 3.7 (2.5)] completed the intervention. Central blood pressure, pulse wave reflection, and aortic pulse wave velocity (PWV) were obtained by an oscillometric monitor. Incremental treadmill exercise testing yielded maximal and submaximal fitness parameters. Participants were randomly assigned to either HIT, MCT, or a control group (CON). The intervention groups trained twice a week over a 12-week intervention period.

Results: After adjustment for between-group baseline differences, a moderate meaningful overall reduction of the augmentation index at 75 min⁻¹ heart rate (AIx@75) was observed [partial eta squared (ηp2) = 0.16; p = 0.06]. With 91% likely beneficial effects, HIT was more effective in reducing AIx@75 than MCT [HIT: pre 22.0 (9.7), post 14.9 (13.0), standardized mean difference (SMD) = 0.62; MCT: pre 16.6 (8.5), post 21.3 (10.4), SMD −0.49]. HIT induced a relevant reduction in central systolic blood pressure [cSBP: pre 118 (23) mmHg, post 110 (16) mmHg, SMD = 0.42] with a 59% possibly beneficial effect compared to CON, while MCT showed larger effects in lowering central diastolic blood pressure [pre 78 (7) mmHg, post 74 (7) mmHg, SMD = 0.61], presenting 60% possibly beneficial effects compared to CON. Central aortic PWV showed no changes in any of the three groups. Migraine days were reduced more successfully by HIT than MCT (HIT: SMD = 1.05; MCT: SMD = 0.43).

Conclusion: HIT but not MCT reduces AIx@75 as a measure of pulse wave reflection and indirect marker of systemic arterial stiffness. Both exercise modalities beneficially affect central blood pressure. HIT proved to be an effective complementary treatment option to reduce vascular dysfunction and blood pressure in migraineurs.

Aortic Stiffness in Aging and Hypertension: Prevention and Treatment with Habitual Aerobic Exercise

PURPOSE OF REVIEW

Habitual aerobic exercise is associated with lower aortic stiffness, as measured by carotid-femoral pulse wave velocity (CFPWV), in middle-aged/older adults without hypertension, but beneficial effects of aerobic exercise on CFPWV in hypertension remain contraversial. Therefore, the focus of this review is to discuss the evidence for and against the beneficial effects of aerobic exercise on aortic stiffness in middle-aged and older adults with hypertension, possible limitations in these studies, and highlight novel directions for future research.

RECENT FINDINGS

Most randomized controlled intervention studies demonstrate that short-term aerobic exercise results in no reductions in CFPWV in middle-aged and/or older adults with treated or treatment-naïve hypertension. Higher aerobic fitness is not associated with lower aortic stiffness among older adults with treated hypertension. Aortic stiffness appears to be resistant to clinically relevant improvements in response to habitual aerobic exercise in the presence of hypertension among middle-aged and older adults.