Reduction in alpha-adrenergic receptor-mediated vascular tone contributes to improved arterial compliance with endurance training

Effects of acute cervical stretching on arterial wall elastic properties

Purpose: Acute (immediate) or regular (mid- or long-term) stretching increases arterial compliance and reduces arterial stiffness. Stretching is widely known to induce arterial functional factor changes, but it is unclear whether stretching alters arterial structural factors. Ultrasound shear wave elastography can quantify the distribution of tissue elastic properties as an index of arterial structural factors. This study thus aimed to examine the effects of acute cervical stretching on arterial wall tissue elastic properties. Methods: Seventeen healthy young adults participated in two different trials for 15 min in random order on separate days: a resting and sitting trial (CON) and a supervised cervical stretching trial (CS). In CS, subjects performed 10 different stretches. At each site, the stretch was held for 30 s followed by a 10-s relaxation period. In CON, subjects rested on a chair for 15 min. Results: After the experiment, carotid arterial compliance, assessed by combined ultrasound imaging and applanation tonometry, was significantly increased in CS, but not in CON. However, there was no significant change in tissue elasticity properties of the arterial wall in either trial, as assessed by ultrasound shear wave elastography. Conclusion: Acute cervical stretching significantly increased carotid artery compliance in young participants, but did not reduce elastic tissue properties (i.e., arterial structural factors) of the carotid artery wall. These results strongly suggest that changes in structural factors have little relation to stretching-induced acute increases in arterial compliance.

Aerobic exercise training reduces cerebrovascular impedance in older adults: a 1-year randomized controlled trial

Older adults have higher cerebrovascular impedance than young individuals which may contribute to chronic brain hypoperfusion. Besides, middle-aged athletes exhibit lower cerebrovascular impedance than their sedentary peers. We examined whether aerobic exercise training (AET) reduces cerebrovascular impedance in sedentary older adults. We conducted a proof-of-concept trial that randomized 73 older adults to 1 yr of AET (n = 36) or stretching and toning (SAT, n = 37) interventions. Cerebrovascular impedance was estimated from simultaneous recordings of carotid artery pressure (CAP) via applanation tonometry and cerebral blood flow velocity (CBFV) in the middle cerebral artery via transcranial Doppler using transfer function analysis. Fifty-six participants completed 1-yr interventions, and 41 of those completed cerebrovascular impedance measurements. AET group showed a significant increase in V̇o2peak after the intervention [estimated marginal mean (95% confidence interval); from 22.8 (21.6 to 24.1) to 24.9 (23.6 to 26.2) mL·kg-1·cm-1, P < 0.001], but not SAT [from 21.7 (20.5 to 22.9) to 22.3 (21.1 to 23.7) mL·kg-1·cm-1, P = 0.114]. Coherence between changes in CBFV and CAP was >0.90 in the frequency range of 0.78-3.12 Hz. The averaged cerebrovascular impedance modulus (Z) in this frequency range decreased after 1-yr AET [from 1.05 (0.96 to 1.14) to 0.95 (0.92 to 1.06) mmHg·s·cm-1, P = 0.023], but not SAT [from 0.96 (0.87 to 1.04) to 1.01 (0.92 to 1.10) mmHg·s·cm-1, P = 0.138]. Reductions in Z were correlated positively with reductions in carotid pulse pressure (r = 0.628, P = 0.004) and inversely with mean CBFV (r = -0.563, P = 0.012) in the AET group. One-year AET reduces cerebrovascular impedance in older adults, which may benefit brain perfusion.NEW & NOTEWORTHY Estimation of cerebrovascular impedance is essential for understanding dynamic cerebral blood flow regulation. This randomized controlled trial demonstrated that aerobic exercise training reduced cerebrovascular impedance in older adults, which may benefit brain perfusion.

Carotid Arterial Compliance and Aerobic Exercise Training in Chronic Traumatic Brain Injury: A Pilot Study

OBJECTIVE

Decreased carotid arterial compliance (CAC) is associated with cerebral microvascular damage, cerebral blood flow (CBF) dysregulation, and increased risk for stroke and dementia, which are reported to be prevalent after traumatic brain injury (TBI). However, the effect of TBI on CAC has not been reported. The purposes of this pilot study were to (1) compare CAC between participants with chronic traumatic brain injury (cTBI) and age-matched healthy control (HC) subjects and (2) to examine whether CAC changed after 3 months of exercise training in those with cTBI.

SETTING

Community based.

PARTICIPANTS

Nineteen participants with cTBI (6-72 months postinjury) and 19 HC matched for age and sex were tested at baseline. The same cTBI cohort was enrolled in a proof-of-concept randomized controlled exercise training program to investigate the effects of 3 months of aerobic exercise training (AET) or nonaerobic stretching and toning (SAT) on cerebrovascular parameters.

DESIGN

Cross-sectional study and randomized controlled trial.

MAIN MEASURES

CAC was measured by tonometry and ultrasonography at the common carotid artery; CBF was measured by ultrasonography at the bilateral internal carotid and vertebral arteries, and pulsatile CBF was measured by transcranial Doppler ultrasonography at the middle cerebral arteries. Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by total CBF.

RESULTS

Relative to HC, the participants with cTBI had lower CAC (0.10 ± 0.03 vs 0.12 ± 0.03 mm 2 /mm Hg, P = .046) and higher CVR (0.17 ± 0.03 vs 0.15 ± 0.03 mm Hg/mL/min, P = .028). CAC tended to increase after AET compared with SAT ( P = .080). Increases in CAC were associated with decreased pulsatile CBF ( r = -0.689, P = .003).

CONCLUSION

These findings suggest that the individuals with cTBI have decreased CAC, which may potentially be improved by AET.

Regular exercise ball training reduces arterial stiffness in sedentary middle-aged males

[Purpose] Reports suggest that static stretching, which improves body flexibility, could reduce arterial stiffness. Regular training using an exercise ball would increase flexibility in a different manner, compared to that from static stretching; however, it remains unclear whether such exercise can reduce arterial stiffness. This study aimed to clarify the effect of exercise ball training on arterial stiffness in sedentary middle-aged participants. [Participants and Methods] Fifteen healthy middle-aged males (age, 52 ± 12 years) were divided into a control group (n=7, CON) and an intervention group (n=8, INT). The CON group did not alter physical activity levels throughout the study period, while the INT group participated in supervised training sessions using an exercise ball for 20-30 min, 5 days/week, for a duration of 4 weeks. [Results] Exercise ball training significantly increased the sit-and-reach test score (CON, -3.8 ± 11.1% vs. INT, 33.8 ± 47.5%) and reduced cardio-ankle vascular index (CON, -0.8 ± 4.1% vs. INT, -5.7 ± 4.1%) and heart-ankle pulse wave velocity (CON, 1.6 ± 4.5% vs. INT, -4.2 ± 4.6%), as an index of arterial stiffness. [Conclusion] Four weeks of supervised training using an exercise ball as well as regular static stretching would increase body flexibility and reduce systemic arterial stiffness among sedentary middle-aged males.

Body height determines carotid stiffness following resistance exercise in young Japanese men

Height is inversely associated with an increase in arterial stiffness after habitual resistance exercise (RE). Considering that RE is performed during exercise prescriptions, the association between height and the acute effects of RE on arterial stiffness should be clarified. We investigated the effects of height on arterial stiffness following transient RE. Thirty-nine young Japanese men were studied under parallel experimental conditions (sham control [seated rest] and RE [5 sets of 10 repetitions at 75% of one-repetition maximum]), which were randomly ordered on two separate days. The subjects were divided into tertiles of height (each group, n = 13). The β-stiffness index (index of arterial stiffness), assessed by carotid pulse pressure and distension, was measured in all subjects. A significant interaction between time, height, and RE was found for the β-stiffness index (P = 0.01). RE significantly increased the β-stiffness index in the lower height group (P < 0.001), but not in the middle and higher height groups. Height was negatively associated with an increase in β-stiffness index following RE, even after controlling the confounders, including exercise volume and changes in heart rate and carotid pulse pressure (P = 0.003). The mediation analysis demonstrated a mediating effect of carotid distension on the relationship between height and changes in the β-stiffness index. These results suggest that short height individuals have increased arterial stiffness following RE due to decreased mechanical distension, rather than through the widening of pulsatile pressure.

One-Year Aerobic Exercise Reduced Carotid Arterial Stiffness and Increased Cerebral Blood Flow in Amnestic Mild Cognitive Impairment

BACKGROUND

Central arterial stiffness and brain hypoperfusion are emerging risk factors of Alzheimer's disease (AD). Aerobic exercise training (AET) may improve central arterial stiffness and brain perfusion.

OBJECTIVE

To investigate the effects of AET on central arterial stiffness and cerebral blood flow (CBF) in patients with amnestic mild cognitive impairment (MCI), a prodromal stage of AD.

METHODS

This is a proof-of-concept, randomized controlled trial that assigned 70 amnestic MCI patients into a 12-month program of moderate-to-vigorous AET or stretching-and-toning (SAT) intervention. Carotid β-stiffness index and CBF were measured by color-coded duplex ultrasonography and applanation tonometry. Total CBF was measured as the sum of CBF from both the internal carotid and vertebral arteries, and divided by total brain tissue mass assessed with MRI to obtain normalized CBF (nCBF). Episodic memory and executive function were assessed using standard neuropsychological tests (CVLT-II and D-KEFS). Changes in cardiorespiratory fitness were measured by peak oxygen uptake (VO2peak).

RESULTS

Total 48 patients (29 in SAT and 19 in AET) were completed one-year training. AET improved VO2peak, decreased carotid β-stiffness index and CBF pulsatility, and increased nCBF. Changes in VO2peak were associated positively with changes in nCBF (r = 0.388, p = 0.034) and negatively with carotid β-stiffness index (r = -0.418, p = 0.007) and CBF pulsatility (r = -0.400, p = 0.014). Decreases in carotid β-stiffness were associated with increases in cerebral perfusion (r = -0.494, p = 0.003). AET effects on cognitive performance were minimal compared with SAT.

CONCLUSION

AET reduced central arterial stiffness and increased CBF which may precede its effects on neurocognitive function in patients with MCI.

Genetic Profile in Genes Associated with Cardiorespiratory Fitness in Elite Spanish Male Endurance Athletes

BACKGROUND

most of the research concerning the influence of genetics on endurance performance has been carried out by investigating target genes separately. However, endurance performance is a complex trait that can stem from the interaction of several genes. The objective of this study was to compare the frequencies of polymorphisms in target genes involving cardiorespiratory functioning in elite endurance athletes vs. non-athlete controls.

METHODS

genotypic frequencies were determined in 123 elite endurance athletes and in 122 non-athletes. Genotyping of ACE (rs4340), NOS3 (rs2070744 and rs1799983), ADRA2a (rs1800544 and rs553668), ADRB2 (rs1042713 and rs1042714), and BDKRB2 (rs5810761) was performed by polymerase chain reaction. The total genotype score (TGS: from 0 to 100 arbitrary units; a.u.) was calculated from the genotype score in each polymorphism.

RESULTS

the mean TGS in non-athletes (47.72 ± 11.29 a.u.) was similar to elite endurance athletes (46.54 ± 11.32 a.u., p = 0.415). The distribution of TGS frequencies were also similar in non-athletes and elite endurance athletes (p = 0.333). There was no TGS cut-off point to discriminate being elite endurance athletes.

CONCLUSIONS

the genetic profile in the selected genes was similar in elite endurance athletes and in controls, suggesting that the combination of these genes does not determine endurance performance.

Exercise during Pregnancy: Developmental Programming Effects and Future Directions in Humans

Epidemiological studies show that low birth weight is associated with mortality from cardiovascular disease in adulthood, indicating that chronic diseases could be influenced by hormonal or metabolic insults encountered in utero. This concept, now known as the Developmental Origins of Health and Disease hypothesis, postulates that the intrauterine environment may alter the structure and function of the organs of the fetus as well as the expression of genes that impart an increased vulnerability to chronic diseases later in life. Lifestyle interventions initiated during the prenatal period are crucial as there is the potential to attenuate progression towards chronic diseases. However, how lifestyle interventions such as physical activity directly affect human offspring metabolism and the potential mechanisms involved in regulating metabolic balance at the cellular level are not known. The purpose of this review is to highlight the effects of exercise during pregnancy on offspring metabolic health and emphasize gaps in the current human literature and suggestions for future research.

Acute increase in arterial stiffness after swimming in cooler water

Cold stimuli increase arterial stiffness, but it has not been explored whether arterial stiffness increases after swimming in cooler water. To investigate the effects of water temperature on changes in arterial stiffness after swimming, 13 men participated in three trials of 20-min swimming in 25 and 30°C water (S25 and S30, respectively) and sitting at poolside (CON) in random order. There were no significant differences between the S25 and S30 trials in mean swimming distance (719 vs. 722 m) and heart rate reserve during swimming (63% vs. 63%). Sublingual temperature was lower after swimming in 25°C water versus before swimming. Aortic pulse wave velocity (aortic PWV, an index of central arterial stiffness based on applanation tonometry) and brachial-ankle pulse wave velocity (baPWV, an index of systemic arterial stiffness based on air plethysmography) were higher 30 min after versus before swimming in 25°C water. Aortic PWV recovered to pre-swimming levels by 60 min after swimming in 25°C water, but baPWV was higher even at 60 min after swimming. PWVs did not change in the CON and S30 trials. Systemic vascular resistance based on Doppler ultrasonography did not change, but forearm vascular resistance based on strain-gauge plethysmography was higher 30 and 60 min after swimming in 25°C water. Heart rate was higher, but stroke volume was lower 30 min after swimming in 25°C water, resulting in no detectable change in cardiac output. In conclusion, arterial stiffness increases acutely after moderate-intensity swimming in cooler water.

Equol-producing status affects exercise training-induced improvement in arterial compliance in postmenopausal women

Central arterial compliance decreases drastically after menopause. Regular intake of soy isoflavone and aerobic exercise increase arterial compliance. The equol is a metabolite of isoflavone daidzein by gut microbiome. We determined whether the equol-producing status affects aerobic exercise-induced improvement in carotid arterial compliance. Forty-three postmenopausal women were assigned to two intervention groups: 1) exercise and isoflavone (Ex+Iso, n = 27 females) or 2) isoflavone interventions (Iso; n = 16 females). Participants of the Ex+Iso intervention group completed an 8-wk aerobic exercise training, and all participants were administered with oral isoflavone supplements during the interventions. The equol-producing status (equol producers or nonproducers) was determined from urine equol concentrations after a soy challenge. In the Ex+Iso intervention group, carotid arterial compliance increased in the equol producers (0.084 ± 0.030→0.117 ± 0.035 mm²/mmHg), but not in the nonproducers (0.089 ± 0.028→0.097 ± 0.026 mm²/mmHg) after the intervention (interaction effect; P < 0.05). The magnitude of increases in carotid arterial compliance was significantly greater in the equol producers than in the non-equol producers (P < 0.05). In the isoflavone intervention group, there were no changes in any parameters after the intervention irrespective of the equol status. These results suggest that equol-producing status is obligatory to aerobic exercise training-induced improvements in central arterial compliance in postmenopausal women.NEW & NOTEWORTHY Isoflavone intake and aerobic exercise increase central artery compliance. Equol, a metabolite of isoflavone daidzein by gut microbiome, has beneficial effects on vascular function. We demonstrated for the first time that the interaction of aerobic exercise and equol production status plays an essential role in improvements in central artery compliance in postmenopausal women. More specifically, the equol-producing status was obligatory to exercise training-induced improvements in central arterial compliance in postmenopausal women.

Dose of Alcohol From Beer Required for Acute Reduction in Arterial Stiffness

Acute beer or alcohol ingestion reduces arterial stiffness, but the dose required to reduce arterial stiffness is unclear. Therefore, this study aimed to determine the acute effects of ingesting various amounts of beer on arterial stiffness in healthy men. Nine men (20–22 years) participated, in eight trials in random order on different days. The participants each consumed 25, 50, 100, or 200 mL of alcohol-free beer (AFB25, AFB50, AFB100, and AFB200) or regular beer (B25, B50, B100, and B200), and were monitored for 60 min thereafter. Arterial stiffness did not significantly change among all AFB and B25. However, B50, B100, and B200 caused a significant decrease in arterial stiffness for approximately 30–60 min: heart-brachial pulse wave velocity (B50: −4.5 ± 2.4%; B100: −3.4 ± 1.3%; B200: −8.1 ± 2.6%); brachial-ankle pulse wave velocity (B50: −0.6 ± 2.0%; B100: −3.3 ± 1.1%; B200: −9.3 ± 3.0%); heart-ankle pulse wave velocity (B50: −3.7 ± 0.3%; B100: −3.3 ± 0.9%; B200: −8.1 ± 2.7%); and cardio-ankle vascular index (B50: −4.6 ± 1.3%; B100: −5.6 ± 0.8%; B200: −10.3 ± 3.1%). Positive control alcoholic beverages reduced arterial stiffness, and these reductions did not significantly differ regardless of the type of beverage. Our data show that consuming about 50 mL of beer can start to reduce arterial stiffness, and that the reduced arterial stiffness is mainly attributable to the alcohol in beer.

The Efficacy of Stretching Exercises on Arterial Stiffness in Middle-Aged and Older Adults: A Meta-Analysis of Randomized and Non-Randomized Controlled Trials

Background: Aerobic exercise is known to reduce arterial stiffness; however, high-intensity resistance exercise is associated with increased arterial stiffness. Stretching exercises are another exercise modality, and their effect on arterial stiffness remains unclear. The purpose of this study was to determine whether stretching exercises reduce arterial stiffness in middle-aged and older adults, performing the first meta-analysis of currently available studies. Methods: We searched the literature for randomized controlled trials (RCTs) and non-RCTs published up to January 2020 describing middle-aged and older adults who participated in a stretching intervention vs. controls without exercise training. The primary and secondary outcomes were changes in arterial stiffness and vascular endothelial function and hemodynamic status. Pooled mean differences (MDs) and standard MDs (SMDs) with 95% confidence intervals (CIs) between the intervention and control groups were calculated using a random effects model. Results: We identified 69 trials and, after an assessment of relevance, eight trials, including a combined total of 213 subjects, were analyzed. Muscle stretching exercises were shown to significantly reduce arterial stiffness and improve vascular endothelial function (SMD: −1.00, 95% CI: −1.57 to −0.44, p = 0.0004; SMD: 1.15, 95% CI: 0.26 to 2.03, p = 0.01, respectively). Resting heart rate (HR) and diastolic blood pressure (DBP) decreased significantly after stretching exercise intervention (MD: −0.95 beats/min, 95% CI: −1.67 to −0.23 beats/min, p = 0.009; MD: −2.72 mm Hg, 95% CI: −4.01 to −1.43 mm Hg, p < 0.0001, respectively) Conclusions: Our analyses suggest that stretching exercises reduce arterial stiffness, HR, and DBP, and improve vascular endothelial function in middle-aged and older adults.

Impact of acute mental stress on segmental arterial stiffness

PURPOSE

It has been reported that acute brief episodes of mental stress (MS) result in a prolonged increase in carotid-femoral pulse wave velocity (cfPWV), an index of aortic stiffness. However, whether acute MS also impacts arterial stiffness in other segments is unclear. The present study aimed to examine the impact of acute MS on segmental arterial stiffness.

METHODS

In the main experiment, 17 young male subjects (mean age, 20.1 ± 0.7 years) performed a 5-min MS and control (CON) task in a random order. Pulse wave velocity (PWV) from the heart to the brachium (hbPWV) and the ankle (haPWV), PWV between the brachial artery and the ankle (baPWV), and the cardio-ankle vascular index (CAVI) were simultaneously measured at baseline and 5, 15, and 30 min after the task.

RESULTS

Compared to baseline values, hbPWV, baPWV, haPWV, and CAVI significantly increased until 30 min after the MS task, whereas these variables did not significantly change following the CON task. At 5 and 30 min after the MS task, percentage changes from baseline were significantly higher in hbPWV (+ 5.2 ± 4.4 and 6.6 ± 4.9%) than in baPWV (+ 2.2 ± 2.1 and 2.2 ± 2.0%) or haPWV (+ 3.6 ± 2.6 and 4.3 ± 2.9%) and were also significantly lower in baPWV than in haPWV.

CONCLUSION

These findings suggest that acute MS elicits an increase in arterial stiffness in various segments and this arterial stiffening is not uniform among the segments.

Middle-aged endurance athletes exhibit lower cerebrovascular impedance than sedentary peers

Because elevated hemodynamic pulsatility could be mechanical stress against the brain, the dampening function of central and cerebral arteries is crucial. Regular endurance exercise training favorably restores the deteriorated dampening function of the aorta and carotid arteries in older populations, yet its effect on cerebrovascular dampening function remains unknown. To address this question, we compared cerebrovascular impedance, a frequency-domain relationship of the cerebral pressure and flow, in 21 middle-aged masters athletes who have been engaged in endurance training and races for >10 yr (MA, 53 ± 4 yr) with sedentary 21 age-matched (MS, 53 ± 5 yr) and 21 young (YS, 29 ± 6 yr) individuals. Using transfer function analysis, cerebrovascular impedance was computed from the simultaneously recorded carotid artery pressure (CAP, via applanation tonometry) and middle cerebral artery blood flow velocity (CBFV, via transcranial Doppler). In the frequency range of 0.78-3.12 Hz, coherence between pulsatile changes in CAP and CBFV was higher than 0.90 in all groups. All subjects exhibited the highest impedance modulus in the range of the first harmonic oscillations (0.78-1.56 Hz) mainly originating from cardiac ejection. Impedance modulus in this range was significantly lower in the MA than MS groups (0.88 ± 0.24 vs. 1.15 ± 0.29 mmHg·s/cm, P = 0.011) and equivalent to the YS (0.92 ± 0.30 mmHg·s/cm). Among middle-aged subjects, higher impedance modulus was correlated with lower mean CBFV (r = -0.776, P < 0.001) and cerebral cortical perfusion evaluated by MRI (r = -0.371, P = 0.015). These results suggest that middle-aged endurance athletes exhibited the significantly lower modulus of cerebrovascular impedance, which is associated with higher CBFV and cerebral cortical perfusion.NEW & NOTEWORTHY Impedance modulus in the range of first harmonic oscillations (0.78-1.56 Hz), which reflects heart rate at rest, was lower in middle-aged endurance athletes than in age-matched sedentary peers and was similar to young individuals. Prolonged endurance training is associated with the improved cerebrovascular dampening function in middle-aged adults. Lower cerebrovascular impedance modulus may contribute to maintaining brain perfusion in midlife.

The effects of exercise on vascular markers and C-reactive protein among obese children and adolescents: An evidence-based review

Numerous studies have evaluated the effects of exercise training on obese children and adolescents. However, the impact of aerobic and/or resistance exercise alone, without any other interventions, on vascular markers and C-reactive protein (CRP) in obese children and adolescents is still not clear. We performed a literature search in Ovid Medline, PubMed, and SCOPUS databases to identify articles on the effects of exercise on vascular markers and CRP among obese children and adolescents, published between January 2009 and May 2019. Only full-text articles in English that reported on the effect of aerobic and/or resistance exercise on the vascular markers pulse wave velocity (PWV), carotid intima-media thickness (CIMT), flow-mediated dilatation (FMD), augmentation index (AIx), or CRP in obese children and adolescents (5-19 years old) were included. The literature search identified 36 relevant articles; 9 articles that fulfilled all the inclusion criteria were selected by two independent reviewers. Aerobic exercise or a combination of aerobic and resistance exercise training significantly improved CIMT and PWV in obese children and adolescents in all studies in which they were measured (2 studies for PWV and 4 studies for CIMT). However, the effects of exercise on FMD and CRP levels were inconclusive, as only half of the studies demonstrated significant improvements (1/2 studies for FMD and 4/8 studies for CRP). The results of our review support the ability of exercise to improve vascular markers such as PWV and CIMT in obese children and adolescents. This finding is important as obesity is a modifiable risk factor of cardiovascular disease (CVD), and exercise may help in reducing the future occurrence of CVD in this population.

Aging and Physiological Lessons from Master Athletes

Sedentary aging is often characterized by physical dysfunction and chronic degenerative diseases. In contrast, masters athletes demonstrate markedly greater physiological function and more favorable levels of risk factors for cardiovascular disease, osteoporosis, frailty, and cognitive dysfunction than their sedentary counterparts. In many cases, age-related deteriorations of physiological functions as well as elevations in risk factors that are typically observed in sedentary adults are substantially attenuated or even absent in masters athletes. Older masters athletes possess greater functional capacity at any given age than their sedentary peers. Impressive profiles of older athletes provide insight into what is possible in human aging and place aging back into the domain of "physiology" rather than under the jurisdiction of "clinical medicine." In addition, these exceptional aging athletes can serve as a role model for the promotion of physical activity at all ages. The study of masters athletes has provided useful insight into the positive example of successful aging. To further establish and propagate masters athletics as a role model for our aging society, future research and action are needed. © 2020 American Physiological Society. Compr Physiol 10:261-296, 2020.

Elevated Muscle Sympathetic Nerve Activity Contributes to Central Artery Stiffness in Young and Middle-Age/Older Adults

Muscle sympathetic nerve activity (MSNA) influences the mechanical properties (ie, vascular smooth muscle tone and stiffness) of peripheral arteries, but it remains controversial whether MSNA contributes to stiffness of central arteries, such as the aorta and carotids. We examined whether elevated MSNA (age-related) would be independently associated with greater stiffness of central (carotid-femoral pulse wave velocity [PWV]) and peripheral (carotid-brachial PWV) arteries, in addition to lower carotid compliance coefficient, in healthy men and women (n=88, age: 19-73 years, 52% men). We also examined whether acute elevations in MSNA without increases in mean arterial pressure using graded levels of lower body negative pressure would augment central and peripheral artery stiffness in young (n=15, 60% men) and middle-age/older (MA/O, n=14, 43% men) adults. Resting MSNA burst frequency (bursts·min^-1) was significantly correlated with carotid-femoral PWV ( R=0.44, P<0.001), carotid-brachial PWV ( R=0.32, P=0.004), and carotid compliance coefficient ( R=0.28, P=0.01) after controlling for sex, mean arterial pressure, heart rate, and waist-to-hip ratio (central obesity), but these correlations were abolished after further controlling for age (all P>0.05). In young and MA/O adults, MSNA was elevated during lower body negative pressure ( P<0.001) and produced significant increases in carotid-femoral PWV (young: Δ+1.3±0.3 versus MA/O: Δ+1.0±0.3 m·s^-1, P=0.53) and carotid-brachial PWV (young: Δ+0.7±0.3 versus MA/O: Δ+0.7±0.5 m·s^-1, P=0.92), whereas carotid compliance coefficient during lower body negative pressure was significantly reduced in young but not MA/O (young: Δ-0.04±0.01 versus MA/O: Δ0.001±0.008 mm²·mm Hg^-1, P<0.01). Collectively, these data demonstrate the influence of MSNA on central artery stiffness and its potential contribution to age-related increases in stiffness of both peripheral and central arteries.

The effect of steady-state CO2 on regional brain blood flow responses to increases in blood pressure via the cold pressor test

The pressure-passive cerebrovasculature is affected by alterations in cerebral perfusion pressure (CPP) and arterial blood gases (e.g., pressure of arterial [Pa]CO₂), where acute changes in either stimulus can influence cerebral blood flow (CBF). The effect of superimposed increases in CPP at different levels of steady-state PaCO₂ on regional CBF regulation is unclear. In 17 healthy participants, we simultaneously recorded continuous heart rate (electrocardiogram), blood pressure (finometer), pressure of end-tidal CO₂ (P_ETCO₂; gas analyzer), and middle (MCA) and posterior (PCA) cerebral artery blood velocity (CBV; transcranial Doppler ultrasound). Three separate CPTs were administered by passive immersion of both feet into 0-1 °C of ice water for 3-min under three randomized and coached steady-state P_ETCO₂ conditions: normocapnia (room air), hypocapnia (-10 Torr; hyperventilation) and hypercapnia (+9 Torr; 5% inspired CO₂;). CBV responses were calculated as the absolute difference (∆) between baseline and mean MCAv and PCAv during the 3-min CPT. Both the ∆MCAv and ∆PCAv responses to the CPT were larger under hypercapnic conditions. The absolute ∆MCAv response was larger than the ∆PCAv during the CPT across all three CO₂ trials. Cerebrovascular CO₂ reactivity (CVR) was larger in the MCA than PCA in both CPT and baseline conditions, but there were no differences in CVR between CPT and baseline conditions. Our data indicate that (a) increases in CO₂ increases the CBV responses to a CPT, (b) the anterior cerebrovasculature is more responsive to a CPT-induced increases in MAP, and (c) although unchanged during a CPT, CVR is larger in the anterior cerebral circulation.

Aortic diastolic pressure decay modulates relation between worsened aortic stiffness and myocardial oxygen supply/demand balance after resistance exercise

High-intensity resistance exercise (RE) increases aortic stiffness and decreases the index of myocardial oxygen supply/demand balance (Buckberg index, BI); there is a correlation between the changes in these parameters. Central hemodynamics during diastole can explain the correlation. We aimed to investigate whether the aortic diastolic decay index mediates the association between changes in aortic stiffness and BI by high-intensity RE. We evaluated the effect of high-intensity RE on aortic stiffness, BI, aortic decay index, and their associations in 52 young men. Subjects were studied under parallel experimental conditions on two separate days. The order of experiments was randomized between RE (5 sets of 10 repetitions at 75% of 1-repetition maximum) and sham control (seated rest). Aortic pulse wave velocity (PWV; index of aortic stiffness), BI, and aortic decay index were measured in all subjects. Aortic decay index was quantified by fitting an exponential curve: P(t) = P₀e^-λt (where λ is decay index, P₀ is end-systolic pressure and t is time from end-systole). Aortic PWV and decay index increased and BI decreased after RE. RE conditions showed that change in the aortic decay index was associated with changes in aortic PWV and changes in aortic PWV were related to changes in BI, although the PWV-BI relationship was not significant after accounting for decay index change. Mediation analysis revealed the mediating effect of the aortic decay index on the relationship between changes in aortic PWV and BI. The present findings suggest that high-intensity RE-induced aortic stiffening worsens myocardial viability by accelerating aortic diastolic exponential decay.NEW & NOTEWORTHY Aortic pulse wave velocity (PWV) and diastolic decay index increased and Buckberg index (BI) decreased after resistance exercise (RE). Mediation analysis revealed a mediating effect of aortic decay index on the relationship between changes in aortic PWV and BI. The present study provides evidence that high-intensity RE-induced aortic stiffening accelerates aortic decay and aortic decay can account for the relationship between aortic stiffening and a deteriorated surrogate marker of myocardial oxygen supply/demand balance induced by high-intensity RE.

Comparisons of low-intensity versus moderate-intensity combined aerobic and resistance training on body composition, muscle strength, and functional performance in older women

OBJECTIVE

This study aimed to examine the effects of exercise order of combined aerobic and low- or moderate-intensity resistance training into the same session on body composition, functional performance, and muscle strength in healthy older women. Furthermore, this study compared the effects of different (low- vs moderate-) intensity combined training.

METHODS

A total of 60 healthy older women (age 61-81 y) were randomly assigned to five groups that performed aerobic exercise before low-intensity resistance training (AR-L, n = 12) or after resistance training (RA-L, n = 12), performed aerobic exercise before moderate-intensity resistance training (AR-M, n = 12) or after resistance training (RA-M, n = 12), or nonintervention control conditions (CON, n = 12). Body composition, functional performance, and muscle strength were evaluated before and after the 10-week training.

RESULTS

No effects of exercise order of combined aerobic and low- or moderate-intensity resistance training (AR-L vs RA-L, AR-M vs RA-M) were observed in body composition, functional performance, or muscle strength, whereas the effects of training intensity of combined training (AR-L vs AR-M, RA-L vs RA-M) were observed on functional performance. All combined trainings significantly increased muscle strength and gait ability (P < 0.01, respectively). Functional reach test significantly increased in the AR-M and RA-M groups (P < 0.01, respectively), and there were significant group differences between AR-L and AR-M (P = 0.002), RA-L and RA-M (P = 0.014).

CONCLUSIONS

Preliminary findings suggest that combined aerobic and low- or moderate-intensity resistance training increases muscle strength and improves gait ability, regardless of the exercise order. Also, greater improvement in dynamic balance capacity, a risk factor associated with falling, is observed in moderate-intensity combined training.

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.

Effects of resistance training on arterial compliance and plasma endothelin-1 levels in healthy men

Arterial compliance (AC) is an index of the elasticity of large arteries. Endothelial dysfunction has been reported to result in reduced arterial compliance, which represents increased arterial stiffness. A reduction in AC is elicited by high-intensity resistance training, however the mechanisms are obscure. Because a single bout of resistance exercise causes a transient increase in circulating plasma endothelin-1 in humans, some vasoconstrictors may play a role in the mechanisms. The present study aimed to investigate whether resistance training-induced decrease in AC is associated with changes in circulating vasoconstrictors levels in young men. Young sedentary men were assigned to control (n=5) or training (n=9) groups. The training group performed four-week high-intensity resistance training (weight training exercise; three sessions/week). We measured AC and plasma levels of endothelin-1, angiotensin II, and norepinephrine before and after intervention. Resistance training significantly decreased AC, whereas the changes in plasma levels of neither endothelin-1, nor angiotensin II, nor norepinephrine were significantly different between the control and the training groups. Moreover, we found no significant correlations between changes in circulating plasma levels (endothelin-1, angiotensin II, and norepinephrine) and in the AC. Despite of no alteration of the resting circulating plasma levels (endothelin-1, etc.), we cannot exclude a possibility that the tissue/local concentrations of vasoconstrictors (endothelin-1, etc.) around the vessels might be increased and also involved in a reduction of AC in the training group. Taken together, the present results suggest that circulating vasoconstrictors (endothelin-1, etc.) in plasma are not involved in a reduction in AC by the resistance training.

Effects of High-Intensity Intermittent Training on Vascular Function in Obese Preadolescent Boys

BACKGROUND

High-intensity intermittent training (HIIT) may serve as an effective alternative to traditional endurance training, since HIIT has been shown to induce greater improvements in aerobic fitness and health-related markers in adult populations. Our objective was to determine whether HIIT and supramaximal high-intensity intermittent training (supra-HIIT) would improve vascular structure and function in obese preadolescent boys.

METHODS

Before the baseline testing, 48 obese preadolescent boys, aged 8-12 years, were randomly assigned into control (CON; n = 16), HIIT (8 × 2 minutes at 90% peak power output, n = 16), and supra-HIIT (8 × 20 seconds at 170% peak power output, n = 16) groups. Both exercise groups performed exercises on a cycle ergometer three times/week for 12 weeks.

RESULTS

After 12 weeks, both HIIT and supra-HIIT did not affect body mass, body fat percentage, and waist circumference. Peak oxygen consumption (VO₂peak) increased in both HIIT and supra-HIIT groups (p < 0.05). Both HIIT and supra-HIIT groups had higher resting metabolic rate than the control group (p < 0.05). A measure of arterial stiffness, brachial-ankle pulse wave velocity, and carotid intima-media thickness decreased after 12 weeks of HIIT and supra-HIIT program (all p < 0.05). Flow-mediated dilation, a measure of endothelium-dependent vasodilation, increased in both HIIT and supra-HIIT groups (all p < 0.05).

CONCLUSIONS

It is concluded that both HIIT and supra-HIIT have favorable effects on aerobic capacity, metabolic rate, vascular function and structure, and blood lipid profile in obese preadolescent boys. HIIT may be a time efficient and effective exercise for preventing future cardiovascular disease in obese children.

Effects of endothelin-related gene polymorphisms and aerobic exercise habit on age-related arterial stiffening: a 10-yr longitudinal study

Increased arterial stiffness has emerged as a strong predictor of future cardiovascular events and all-cause mortality. The aim of this study was to elucidate influences of endothelin (ET)-related genetic polymorphisms and regular physical activity on age-related arterial stiffening through a 10-yr longitudinal study. A decadal change in brachial-ankle pulse wave velocity (baPWV), an index of arterial stiffness, was evaluated retrospectively among 92 volunteers (63 ± 14 yr, 51 men). The targeted single-nucleotide polymorphisms were ET-A receptor SNP rs5333 (ET-A) and ET-B receptor SNP rs5351 (ET-B). Subjects with either ET-A TC or CC genotypes exhibited significantly greater increases in baPWV (+15.3 ± 11.7 and +16.6 ± 15.7%/dec, respectively) than ET-A TT genotype holders (+9.2 ± 9.0%/dec), whereas subjects with the ET-B GG genotype showed a significantly greater increase in baPWV (+17.7 ± 14.1%/dec) than other ET-B genotype holders (AA: +9.5 ± 10.0%/dec; AG: +11.2 ± 9.6%/dec). The combination of these ET-related genetic risks was associated with a 2.4 times greater decadal increase in baPWV compared with no genetic risk (+8.1 ± 8.4 vs. 19.5 ± 16.0%/dec). In contrast, individuals engaging in >15 METs·h/wk of aerobic exercise showed substantially smaller increases in baPWV (+5.0 ± 9.7%/dec) compared with their physically inactive peers (approximately +13%/dec). These differences remained significant after adjusting for confounding factors, including baseline baPWV and ET-related genotype risk. Our current longitudinal study found that ET-related gene polymorphisms contribute to diverse age-related changes in arterial stiffness, and that regular sufficient aerobic exercise attenuates the age-related arterial stiffening independently of ET-related gene polymorphisms. NEW & NOTEWORTHY This 10-yr longitudinal study suggests that endothelin-related gene polymorphisms contribute to divergent increases in arterial stiffness with advancing age, whereas regular sufficient aerobic exercise attenuates age-related arterial stiffening independently of ET-related gene polymorphisms. This notion partly supports prevailing evidence that regular aerobic exercise contributes to a lower incidence of cardiovascular disease.

Greater Progression of Age-Related Aortic Stiffening in Adults with Poor Trunk Flexibility: A 5-Year Longitudinal Study

Purpose: Having a low level of physical fitness, especially cardiorespiratory fitness, appears to accelerate age-related aortic stiffening. Whereas, some studies have reported that trunk flexibility is a component of physical fitness, it is also negatively associated with arterial stiffening independent of cardiorespiratory fitness in cross-sectional studies. However, no long-term longitudinal study has determined whether poor trunk flexibility accelerates the progression of age-related aortic stiffening. We examined trunk flexibility and aortic stiffness progression in a 5-year longitudinal study.

Methods and Results: A total of 305 apparently healthy men and women participated in this study (49.6 ± 9.5 years of age). Trunk flexibility was measured using a sit-and-reach test. Aortic stiffness was assessed using carotid-femoral pulse wave velocity (cfPWV) at baseline and after 5 years. Analysis of covariance (ANCOVA) was used to assess the association of the annual rate of cfPWV across flexibility levels (low, middle, high). There were no significant differences in baseline cfPWV among the three groups (835 ± 164, 853 ± 140, 855 ± 2.68 cm/s; P = 0.577). Annual ΔcfPWV was significantly higher in the low-flexibility group than in the high-flexibility group (P = 0.009). ANCOVA revealed an inverse relationship between flexibility level and annual ΔcfPWV (14.41 ± 2.73, 9.79 ± 2.59, 2.62 ± 2.68 cm/s/year; P for trend = 0.011). Multiple regression analysis revealed that baseline sit and reach (β = −0.12, −0.70 to −0.01) was independently correlated with ΔcfPWV following adjustment for baseline peak oxygen uptake, age, sex, body fat, heart rate, and cfPWV. The 5-year change in cfPWV was not significantly correlated with 5-year change in sit-and-reach performance (P = 0.859).

Conclusion: Poor trunk flexibility is associated with greater progression of age-related aortic stiffening in healthy adults. However, we failed to confirm a significant association between 5-year change in aortic stiffness and 5-year change in trunk flexibility. The association between increased age-related increase in aortic stiffness and deterioration in flexibility due to age may require observation for more than 5 years.

Arterial stiffness in young adult swimmers

PURPOSE

Habitual Aerobic exercise reduces arterial stiffness, but effects of habitual swimming on arterial stiffness are not yet fully understood. Swimming can also increase systolic blood pressure (BP) in normotensive individuals. Accordingly, this cross-sectional study aimed to investigate arterial stiffness in young adult swimmers after considering the influence of BP.

METHODS

Participants comprised 41 men (18-21 years), including 15 untrained controls (C), 11 competitive cyclists (aerobic-trained athletes; A), and 15 competitive swimmers (S). Arterial stiffness was assessed by brachial-ankle pulse-wave velocity (baPWV), heart-ankle pulse-wave velocity (haPWV), and cardio-ankle vascular index (CAVI). CAVI is the measurement of arterial stiffness that is theoretically adjusted by BP.

RESULTS

Although physical characteristics and handgrip strength did not differ between groups, peak oxygen uptake was significantly greater in A and S than in C. A tendency towards higher systolic BP and a significantly higher pulse pressure were found in S as compared to C and A. Most importantly, baPWV was significantly lower in A than in C or S, and no significant difference in baPWV was observed between C and S (C, 1027 ± 25; A, 852 ± 23; S, 1032 ± 24 cm/s). No significant difference in haPWV was observed. However, CAVI was significantly lower in A and S than in C, and did not differ significantly between A and S (C, 5.8 ± 0.2; A, 5.1 ± 0.2; S, 5.3 ± 0.2 unit).

CONCLUSION

These findings indicate that arterial stiffness in young adult swimmers is lower than in age-matched sedentary controls and similar to land-based aerobic-exercise individuals, after considering the influences of BP.

Reduced large elastic artery stiffness with regular aerobic exercise in middle-aged and older adults: potential role of suppressed nuclear factor κ B signalling

OBJECTIVE

Aortic pulse-wave velocity (aPWV) increases with age and is a strong independent predictor of incident cardiovascular diseases (CVDs) in healthy middle-aged and older adults. aPWV is lower in middle-aged and older adults who perform regular aerobic exercise than in their sedentary peers. As exercise is associated with reduced systemic inflammation, we hypothesized that suppression of the pro-inflammatory transcription factor nuclear factor κ B (NFκB) may mediate this process.

METHODS

aPWV was measured in young sedentary [n = 10, blood pressure (BP) 108 ± 3/59 ± 2 mmHg; mean ± SEM], middle-aged and older sedentary (n = 9, 124 ± 7/73 ± 5 mmHg) and middle-aged and older aerobic exercise-trained (n = 12, 110 ± 4/67 ± 2 mmHg) healthy, nonhypertensive men and women.

RESULTS

Baseline aPWV increased with age [626 ± 14 (young sedentary) vs. 859 ± 49 (middle-aged and older sedentary) cm/s, P < 0.001] but was 20% lower in middle-aged and older trained (686 ± 30 cm/s) than in middle-aged and older sedentary (P < 0.005). Short-term (4 days  x  2500-4500 mg) treatment with the NFκB inhibitor salsalate (randomized, placebo-controlled cross-over design) reduced aPWV (to 783 ± 44 cm/s, P < 0.05) without changing BP (P = 0.40) or heart rate (P = 0.90) in middle-aged and older sedentary, but had no effect in young sedentary (623 ± 19) or middle-aged and older trained (699 ± 30). Following salsalate treatment, aPWV no longer was significantly different in middle-aged and older sedentary vs. middle-aged and older trained (P = 0.29). The reduction in aPWV with salsalate administration was inversely related to baseline (placebo) aPWV (r = -0.60, P < 0.001).

CONCLUSION

These results support the hypothesis that suppressed NFκB signalling may partially mediate the lower aortic stiffness in middle-aged and older adults who regularly perform aerobic exercise. Because aPWV predicts incident cardiovascular events in this population, this suggests that tonic suppression of NFκB signalling in middle-aged and older exercising adults may potentially lower cardiovascular risk.

A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit.

Four weeks of regular static stretching reduces arterial stiffness in middle-aged men

Trunk flexibility may be associated with arterial stiffness in young, middle-aged, and older healthy men after adjusting for blood pressure. This study assessed the effects of 4 weeks of regular static stretching on arterial stiffness in middle-aged men. Sixteen healthy men (43 ± 3 years) were assigned to control or intervention groups (n = 8 each). The control group did not alter their physical activity levels throughout the study period. The intervention group participated in five supervised stretching sessions per week for 4 weeks. Each session comprised 30 min of mild stretching that moved the major muscle groups through the full range of motion and stretches were held three times for 20 s at the end range. Flexibility was assessed by sit-and-reach test. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI). Four weeks of stretching increased sit-and-reach (Control, Pre: 31.4 ± 2.1, Post: 30.8 ± 2.7 vs. Intervention, Pre: 30.6 ± 5.3, Post: 43.9 ± 4.3 cm), and reduced baPWV (Control, Pre: 1204 ± 25, Post: 1205 ± 38 vs. Intervention, Pre: 1207 ± 28, Post: 1145 ± 19 cm/s) and CAVI (Control, Pre: 7.6 ± 0.3, Post: 7.5 ± 0.3 vs. Intervention, Pre: 7.7 ± 0.2, Post: 7.2 ± 0.2 units) in the intervention group. However, the change in sit-and-reach did not significantly correlate with the changes in arterial stiffness. These findings suggest that short-term regular stretching induces a significant reduction in arterial stiffness in middle-aged men.

The influence of central arterial compliance on cerebrovascular hemodynamics: insights from endurance training intervention

Normally, central elastic arteries (e.g., aorta and common carotid artery) effectively buffer cardiac pulsation-induced flow/pressure fluctuations. With advancing age, arterial stiffening deteriorates this function and produces the greater cerebral hemodynamic pulsatility that impacts vulnerable brain tissue. It is well known that the buffering function of the central artery is improved by regular aerobic exercise, but the influence of endurance training on the pulsatile component of cerebral hemodynamics remains poorly understood. To characterize the functional role of the central artery at the heart-brain hemodynamic connection comprehensively, we assessed relations among the endurance training-induced changes in the left ventricle (LV), carotid arterial compliance, and cerebral hemodynamics. Thirteen collegiate tennis players (20 ± 1 yr) underwent a 16-wk endurance training intervention designed for improving cardiovascular function. Expectedly, maximal oxygen uptake (V̇o2peak), LV ejection velocity (via Doppler ultrasound), and the maximal rate of pressure increase of estimated aortic pressure waveform (via general transfer function) improved after the training intervention, whereas middle cerebral arterial (MCA) hemodynamics (via transcranial Doppler), such as mean and pulsatile flow velocities, remained unchanged. Carotid arterial compliance (via ultrasound and applanation tonometry) increased after the training intervention, and a larger increase in carotid arterial compliance was significantly associated with the greater attenuations of pulsatile MCA velocity ( r = −0.621) normalized by mean MCA velocity. These results suggest that the training-induced improvement of carotid artery Windkessel function might offset the expected increase in the pulsatile component of cerebral perfusion induced by the enhanced LV systolic function.

Does aerobic exercise mitigate the effects of cigarette smoking on arterial stiffness?

The largest percentage of mortality from tobacco smoking is cardiovascular-related. It is not known whether regular participation in exercise mitigates the adverse influence of smoking on vasculature. Accordingly, the authors determined whether regular aerobic exercise is associated with reduced arterial stiffness in men who smoke cigarettes. Using a cross-sectional study design, 78 young men were studied, including sedentary nonsmokers (n=20), sedentary smokers (n=12), physically active nonsmokers (n=21), and physically active smokers (n=25). Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). There were no group differences in height, body fat, and systolic and diastolic blood pressure. As expected, both physically active groups demonstrated greater maximal oxygen consumption and lower heart rate at rest than their sedentary peers. The sedentary smokers demonstrated greater baPWV than the sedentary nonsmokers (11.8±1 m/s vs 10.6±1 m/s, P=.036). baPWV values were not different between the physically active nonsmokers and the physically active smokers (10.8±1 m/s vs 10.7±1 m/s). Chronic smoking is associated with arterial stiffening in sedentary men but a significant smoking-induced increase in arterial stiffness was not observed in physically active adults. These results are consistent with the idea that regular participation in physical activity may mitigate the adverse effects of smoking on the vasculature.

Association of physical activity in childhood and early adulthood with carotid artery elasticity 21 years later: the cardiovascular risk in Young Finns Study

BACKGROUND

Decreased arterial elasticity is a risk factor for several cardiovascular outcomes. Longitudinal data on the effect of physical activity in youth on adult arterial elasticity are limited. The aim of this study was to determine the long-term effects of physical activity in children and young adults on carotid artery elasticity after 21 years of follow-up.

METHODS AND RESULTS

Participants were 1417 children (aged 9 to 15 years) and 999 young adults (aged 18 to 24 years) from the prospective Cardiovascular Risk in Young Finns Study. Participants had questionnaire measures of leisure-time physical activity available from 1986 and ultrasound-derived indices of carotid artery elasticity measured in 2007. Carotid artery elasticity indices were distensibility (%/10 mm Hg), Young's elastic modulus (kPa), and stiffness index (unitless). Physical activity at age 18 to 24 years was directly associated with distensibility (β=0.068, P=0.014) and inversely with Young's elastic modulus (β=-0.057, P=0.0037) and indirectly with stiffness index (β=-0.050, P=0.0028) 21 years later in males and females. The associations remained after adjustment for age, sex, body mass index, smoking, systolic blood pressure, serum lipids and insulin, and 21-year change in physical activity. At age 9 to 15 years, the favorable association, remaining after adjustment, was found in males (distensibility [β=0.097, P=0.010], Young's elastic modulus [β=-0.060, P=0.028], and stiffness index [β=-0.062, P=0.007]) but not in females (P=0.70, P=0.85, and P=0.91, respectively).

CONCLUSIONS

Leisure-time physical activity in boys and young adults is associated with carotid artery elasticity later in life, suggesting that higher levels of physical activity in youth may benefit future cardiovascular health.

Effect of acute resistance exercise on carotid artery stiffness and cerebral blood flow pulsatility

Arterial stiffness is associated with cerebral flow pulsatility. Arterial stiffness increases following acute resistance exercise (RE). Whether this acute RE-induced vascular stiffening affects cerebral pulsatility remains unknown. Purpose: To investigate the effects of acute RE on common carotid artery (CCA) stiffness and cerebral blood flow velocity (CBFv) pulsatility. Methods: Eighteen healthy men (22 ± 1 yr; 23.7 ± 0.5 kg·m⁻²) underwent acute RE (5 sets, 5-RM bench press, 5 sets 10-RM bicep curls with 90 s rest intervals) or a time control condition (seated rest) in a randomized order. CCA stiffness (β-stiffness, Elastic Modulus (Ep)) and hemodynamics (pulsatility index, forward wave intensity, and reflected wave intensity) were assessed using a combination of Doppler ultrasound, wave intensity analysis and applanation tonometry at baseline and 3 times post-RE. CBFv pulsatility index was measured with transcranial Doppler at the middle cerebral artery (MCA). Results: CCA β-stiffness, Ep and CCA pulse pressure significantly increased post-RE and remained elevated throughout post-testing (p < 0.05). No changes in MCA or CCA pulsatility index were observed (p > 0.05). There were significant increases in forward wave intensity post-RE (p < 0.05) but not reflected wave intensity (p > 0.05). Conclusion: Although acute RE increases CCA stiffness and pressure pulsatility, it does not affect CCA or MCA flow pulsatility. Increases in pressure pulsatility may be due to increased forward wave intensity and not pressure from wave reflections.

Lack of changes in carotid artery compliance with systemic nitric oxide synthase inhibition

Proximal large elastic arteries (ascending aorta and carotid artery) have an important role in buffering the pulsatile pressure generated from the left ventricle, which forwards continuous peripheral blood flow and protects the brain microcirculation from end-organ damage. Although compliance of distal conduit arteries (extremities' arteries) is attenuated by the nitric oxide synthase (NOS) inhibition, it is yet unknown whether compliance of proximal elastic arteries changes by the systemic NOS inhibition. To address this question, we measured central artery compliance in 17 young adults (26±1 years) who underwent intravenous infusions of N(G)-monomethyl-L-arginine (L-NMMA) or saline (placebo) on separate days. Following the systemic NOS inhibition, the mean arterial pressure (MAP), total peripheral resistance and aortic augmentation index were significantly increased. However, carotid artery compliance was not affected significantly (from 0.10±0.01 to 0.11±0.01 mm2) per mmHg) and the β-stiffness index (an index of arterial compliance adjusted for the distending pressure) tended to decrease (from 6.63±0.35 to 6.06±0.42 a.u., P=0.07). These parameters were not altered with saline infusion. Changes in the β-stiffness index tended to correlate negatively with the corresponding changes in MAP (r = -0.31, P=0.07). These results suggest that carotid artery compliance remains unchanged during the systemic NOS inhibition in spite of systemic vasoconstriction.

Pre-existing endothelial cell activation predicts vasoplegia after mitral valve surgery

OBJECTIVES

Post-cardiac surgery vasoplegia is a common complication of cardiac surgery, characterized by profound loss of systemic vascular resistance. This results in severe hypotension, high cardiac output and metabolic acidosis reflecting inadequate tissue perfusion. The pathophysiological mechanisms underlying this syndrome remain unknown. We hypothesized that this vasoplegia reflects endothelial dysfunction, either as pre-existing condition or as a consequence of the surgical procedure.

METHODS

To examine these mechanisms, six established and distinct markers of endothelial cell activation were measured pre- and perioperatively in patients undergoing mitral valve surgery. Arterial (radial artery) and myocardial venous blood samples (coronary sinus) were collected simultaneously over the reperfused heart at various time points during the first hour after reperfusion. Additional samples were collected at baseline (brachial vein) and 1 day post-reperfusion (radial artery). Post-cardiac surgery vasoplegia was defined as a mean arterial blood pressure of <60 mmHg, with a cardiac index of ≥2.2 l/min/m(2) treated with continuous intravenous administration of norepinephrine.

RESULTS

No myocardial release of endothelial cell activation markers was observed upon reperfusion in patients with vasoplegia (n = 15; mean age 71 years, 73% male). In contrast, in patients without vasoplegia (n = 24; mean age 64 years, 54% male), reperfusion was characterized by a myocardial release of three endothelial cell activation markers. Myocardial von Willebrand Factor propeptide, osteoprotegerin and interleukin-8 were increased 107% (P < 0.001), 106% (P = 0.02) and 116% (P = 0.009), respectively, compared with arterial levels upon reperfusion. Similar systemic levels of all markers were found upon reperfusion in both groups, except for 120% increased soluble P-selectin (sP-selectin) levels in vasoplegia patients (P = 0.03). Remarkably, postoperative vasoplegia was identified with baseline von Willebrand Factor propeptide levels with a cut-off value of 11.9 nM as well as with baseline sP-selectin levels with a cut-off value of 64.4 ng/ml.

CONCLUSIONS

Pre-existing endothelial cell activation, reflected by higher baseline von Willebrand Factor propeptide and sP-selectin levels, is a predisposing factor for post-cardiac surgery vasoplegia. The pre-existing endothelial cell activation may have resulted in desensibilization of endothelium in patients who develop vasoplegic syndrome, resulting in no myocardial release of endothelial cell activation markers upon reperfusion.

Aerobic training-induced improvements in arterial stiffness are not sustained in older adults with multiple cardiovascular risk factors

There is a well-established relationship between increased arterial stiffness and cardiovascular mortality. We examined whether a long-term aerobic exercise intervention (6 months) would increase arterial compliance in older adults with hypertension complicated by Type 2 diabetes (T2DM) and hyperlipidemia. A total of 52 older adults (mean age 69.3±0.6 years, 30 males and 22 females) with diet/oral hypoglycemic-controlled T2DM, hypertension and hypercholesterolemia were recruited. Subjects were randomly assigned to one of two groups: an aerobic group (6 months vigorous aerobic exercise, AT group) and a non-aerobic group (6 months of no aerobic exercise, NA group). Arterial stiffness was measured as pulse-wave velocity (PWV) using the Complior device. Aerobic training decreased arterial stiffness as measured by both radial (P=0.001, 2-way analysis of variance with repeated measures) and femoral (P=0.002) PWV. This was due to a decrease in arterial stiffness in the AT group after 3 months of training, which was not maintained after 6-month training for either radial (P=0.707) or femoral (P=0.680) PWV. Our findings indicate that in older adults with multiple cardiovascular risk factors, short-term improvements in arterial stiffness became attenuated over the long term.

Contribution of blood viscosity in the assessment of flow-mediated dilation and arterial stiffness

Flow-mediated dilation (FMD) is a non-invasive index of endothelial function. In an attempt to standardize FMD for shear stimulus, shear rate (velocity/diameter), rather than shear stress (viscosity*velocity/diameter), is commonly used as a surrogate measure, although it is limited by individual differences in blood viscosity. The purpose of this study was to determine the contribution of whole blood viscosity to FMD and other key measures of vascular function. Blood viscosity, FMD, carotid artery compliance, and carotid-femoral pulse wave velocity (cfPWV) were measured in 98 apparently healthy adults varying widely in age (18-63 years). Whole blood viscosity was not significantly correlated with FMD, cfPWV, or carotid artery compliance. Shear rate was a stronger correlate with FMD than shear stress that takes blood viscosity into account (r = 0.43 vs 0.28). No significant differences were observed between whole blood viscosity and traditional risk factors for cardiovascular disease. Age was positively correlated with cfPWV (r = 0.65, p < 0.001) and negatively correlated with FMD (r = -0.24, p < 0.05) and carotid artery compliance (r = -0.45, p < 0.01). Controlling for viscosity did not reduce the strength of these relations. These results indicate that whole blood viscosity does not significantly impact measures of vascular function and suggests that the common practice to use shear rate, rather than shear stress, in the adjustment of FMD is valid.

Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement

Background

Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement.

Methods

Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API.

Results

The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P < 0.05), cfPWV (r = -0.49, P < 0.05), and carotid arterial compliance (r = 0.32, P < 0.05). A stepwise multiple regression analysis demonstrated that baPWV and carotid arterial compliance were the independent determinants of API, and that API was the independent determinant of baPWV and carotid arterial compliance.

Conclusions

These results suggest that our method can simply and simultaneously evaluate arterial stiffness and blood pressure based on oscillometric measurements of blood pressure.

Exhaustive swimming differentially inhibits P2X1 receptor- and α1-adrenoceptor-mediated vasoconstriction in isolated rat arteries

AIM

To investigate the effects of exhaustive swimming exercise on P2X1 receptor- and α1-adrenoceptor-mediated vasoconstriction of different types of arteries in rats.

METHODS

Male Wistar rats were divided into 2 groups: the sedentary control group (SCG) and the exhaustive swimming exercise group (ESEG). The rats in the ESEG were subjected to a swim to exhaustion once a day for 2 weeks. Internal carotid, caudal, pulmonary, mesenteric arteries and aorta were dissected out. Isometric vasoconstrictive responses of the arteries to α,β-methylene ATP (α,β-MeATP) or noradrenaline (NA) were recorded using a polygraph.

RESULTS

The exhaustive swimming exercise did not produce significant change in the EC(50) values of α,β-MeATP or NA in vasoconstrictive response of most of the arteries studied. The exhaustive swimming exercise inhibited the vasoconstrictive responses to P2X1 receptor activation in the internal carotid artery, whereas it reduced the maximal vasoconstrictive responses to α1-adrenoceptor stimulation in the caudal, pulmonary, mesenteric arteries and aorta. The rank order of the reduction of the maximal vasoconstriction was as follows: mesenteric, pulmonary, caudal, aorta.

CONCLUSION

Exhaustive swimming exercise differentially affects the P2X1 receptor- and α1-adrenoceptor-regulated vasoconstriction in internal carotid artery and peripheral arteries. The ability to preserve purinergic vasoconstriction in the peripheral arteries would be useful to help in maintenance of the basal vascular tone during exhaustive swimming exercise.