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Paul Bhella

The effect of lifelong endurance exercise on cardiovascular structure and exercise function in women.

Mon, 05/04/2020 - 08:55
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The effect of lifelong endurance exercise on cardiovascular structure and exercise function in women.

J Physiol. 2020 Apr 29;:

Authors: Carrick-Ranson G, Sloane NM, Howden EJ, Bhella PS, Sarma S, Shibata S, Fujimoto N, Hastings JL, Levine BD

KEY POINTS: The beneficial effects of sustained or lifelong (>25 years) endurance exercise on cardiovascular structure and exercise function have been largely established in men. The current findings indicate that committed (≥ 4 weekly exercise sessions) lifelong exercise results in substantial benefits in exercise capacity (V̇O2 max), cardiovascular function at submaximal and maximal exercise, left ventricular mass and compliance, and blood volume compared to similarly aged or even younger (middle-age) untrained women. Endurance exercise training should be considered a key strategy to prevent cardiovascular disease with aging in women as well as men.
ABSTRACT: This study was a retrospective, cross-sectional analysis of exercise performance and left ventricular (LV) morphology in 70 women to examine whether women who have performed regular, lifelong endurance exercise acquire the same beneficial adaptations in cardiovascular structure and function and exercise performance that have been reported previously in men. Three groups of women were examined: 1) 35 older (>60 years) untrained women (older untrained, OU), 2) 13 older women who had consistently performed 4 or more endurance exercise sessions weekly for at least 25 years (older trained, OT), and 3) 22 middle-aged (range 35-59 years) untrained women (middle-age untrained, MU) as a reference control for the appropriate age-related changes. Oxygen uptake (V̇O2 ) and cardiovascular function [cardiac output (Q̇); stroke volume (SV)] (acetylene rebreathing) were examined at rest, steady-state submaximal exercise, and maximal exercise (maximal oxygen uptake, V̇O2 max). Blood volume (CO rebreathing) and LV mass (cardiac MRI), plus invasive measures of static and dynamic chamber compliance were also examined. V̇O2 max (p < 0.001) and maximal exercise Q̇ and SV were larger in older trained women compared to the two untrained groups (∼17% and ∼27% for Q̇ and SV respectively versus MU; ∼40% and ∼38% versus OU, all p < 0.001). Blood volume ( ) and LV mass index (g.m2 ) were larger in OT versus OU (∼11% and ∼16% respectively, both p ≤ 0.015) Static LV chamber compliance was greater in OT compared to both untrained groups (median (25 - 75%): MU: 0.065(0.049 - 0.080); OU: 0.085(0.061 - 0.138); OT: 0.047(0.031 - 0.054), p ≤ 0.053). Collectively, these findings indicate that lifetime endurance exercise appears to be extremely effective at preserving or even enhancing cardiovascular structure and function with advanced age in women. This article is protected by copyright. All rights reserved.

PMID: 32347540 [PubMed - as supplied by publisher]

The effect of lifelong exercise frequency on arterial stiffness.

Fri, 10/25/2019 - 19:28
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The effect of lifelong exercise frequency on arterial stiffness.

J Physiol. 2018 07;596(14):2783-2795

Authors: Shibata S, Fujimoto N, Hastings JL, Carrick-Ranson G, Bhella PS, Hearon CM, Levine BD

KEY POINTS: This study examined the effect of different 'doses' of lifelong (>25 years) exercise on arterial stiffening (a hallmark of vascular ageing) in older adults. There are clear dose-dependent effects of lifelong exercise training on human arterial stiffness that vary according to the site and size of the arteries. Similar to what we have observed previously with ventricular stiffening, 4-5 days week-1 of committed exercise over a lifetime are necessary to preserve 'youthful' vascular compliance, especially of the large central arteries. Casual exercise training of two to three times per week may be sufficient for middle-sized arteries like the carotid to minimize arterial stiffening with ageing. However, there is little effect of exercise training on the small-sized peripheral arteries at any dose.
ABSTRACT: Central arterial stiffness increases with sedentary ageing. While near-daily, vigorous lifelong (>25 years) endurance exercise training prevents arterial stiffening with ageing, this rigorous routine of exercise training over a lifetime is impractical for most individuals. The aim was to examine whether a less frequent 'dose' of lifelong exercise training (four to five sessions per week for > 30 min) that is consistent with current physical activity recommendations elicits similar benefits on central arterial stiffening with ageing. A cross-sectional examination of 102 seniors (>60 years old) who had a consistent lifelong exercise history was performed. Subjects were stratified into four groups based on exercise frequency as an index of exercise 'dose': sedentary: fewer than two sessions per week; casual exercisers: two to three sessions per week; committed exercisers: four to five sessions per week; and Masters athletes: six to seven sessions per week plus regular competitions. Detailed measurements of arterial stiffness and left ventricular afterload were collected. Biological aortic age and central pulse wave velocity were younger in committed exercisers and Masters athletes compared to sedentary seniors. Total arterial compliance index (TACi) was lower, while carotid β-stiffness index and effective arterial elastance were higher in sedentary seniors compared to the other groups. There appeared to be a dose-response threshold for carotid β-stiffness index and TACi. Peripheral arterial stiffness was not significantly different among the groups. These data suggest that four to five weekly exercise sessions over a lifetime is associated with reduced central arterial stiffness in the elderly. A less frequent dose of lifelong exercise (two to three sessions per week) is associated with decreased ventricular afterload and peripheral resistance, while peripheral arterial stiffness is unaffected by any dose of exercise.

PMID: 29781119 [PubMed - indexed for MEDLINE]

Effect of centrally acting angiotensin converting enzyme inhibitor on the exercise-induced increases in muscle sympathetic nerve activity.

Fri, 10/25/2019 - 19:28
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Effect of centrally acting angiotensin converting enzyme inhibitor on the exercise-induced increases in muscle sympathetic nerve activity.

J Physiol. 2018 06;596(12):2315-2332

Authors: Moralez G, Jouett NP, Tian J, Zimmerman MC, Bhella P, Raven PB

KEY POINTS: The arterial baroreflex's operating point pressure is reset upwards and rightwards from rest in direct relation to the increases in dynamic exercise intensity. The intraneural pathways and signalling mechanisms that lead to upwards and rightwards resetting of the operating point pressure, and hence the increases in central sympathetic outflow during exercise, remain to be identified. We tested the hypothesis that the central production of angiotensin II during dynamic exercise mediates the increases in sympathetic outflow and, therefore, the arterial baroreflex operating point pressure resetting during acute and prolonged dynamic exercise. The results identify that perindopril, a centrally acting angiotensin converting enzyme inhibitor, markedly attenuates the central sympathetic outflow during acute and prolonged dynamic exercise.
ABSTRACT: We tested the hypothesis that the signalling mechanisms associated with the dynamic exercise intensity related increases in muscle sympathetic nerve activity (MSNA) and arterial baroreflex resetting during exercise are located within the central nervous system. Participants performed three randomly ordered trials of 70° upright back-supported dynamic leg cycling after ingestion of placebo and two different lipid soluble angiotensin converting enzyme inhibitors (ACEi): perindopril (high lipid solubility), captopril (low lipid solubility). Repeated measurements of whole venous blood (n = 8), MSNA (n = 7) and arterial blood pressures (n = 14) were obtained at rest and during an acute (SS1) and prolonged (SS2) bout of steady state dynamic exercise. Arterial baroreflex function curves were modelled at rest and during exercise. Peripheral venous superoxide concentrations measured by electron spin resonance spectroscopy were elevated during exercise and were not altered by ACEi at rest (P ≥ 0.4) or during exercise (P ≥ 0.3). Baseline MSNA and mean arterial pressure were unchanged at rest (P ≥ 0.1; P ≥ 0.8, respectively). However, during both SS1 and SS2, the centrally acting ACEi perindopril attenuated MSNA compared to captopril and the placebo (P < 0.05). Arterial pressures at the operating point and threshold pressures were decreased with perindopril from baseline to SS1 with no further changes in the operating point pressure during SS2 under all three conditions. These data suggest that centrally acting ACEi is significantly more effective at attenuating the increase in the acute and prolonged exercise-induced increases in MSNA.

PMID: 29635787 [PubMed - indexed for MEDLINE]

Isometric handgrip echocardiography: A noninvasive stress test to assess left ventricular diastolic function.

Wed, 01/30/2019 - 08:31
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Isometric handgrip echocardiography: A noninvasive stress test to assess left ventricular diastolic function.

Clin Cardiol. 2017 Dec;40(12):1247-1255

Authors: Jake Samuel T, Beaudry R, Haykowsky MJ, Sarma S, Park S, Dombrowsky T, Bhella PS, Nelson MD

BACKGROUND: Cycle exercise echocardiography is a useful tool to "unmask" diastolic dysfunction; however, this approach can be limited by respiratory and movement artifacts. Isometric handgrip avoids these issues while reproducibly increasing afterload and myocardial oxygen demand.
HYPOTHESIS: Isometric handgrip echocardiography (IHE) can differentiate normal from abnormal diastolic function.
METHODS: First recruited 19 young healthy individuals (mean age, 24 ± 4 years) to establish the "normal" response. To extend these observations to a more at-risk population, we performed IHE on 17 elderly individuals (mean age, 72 ± 6 years) with age-related diastolic dysfunction. The change in the ratio of mitral valve inflow velocity to lateral wall tissue velocity (E/e'), a surrogate for left ventricular filling pressure, was used to assess the diastolic stress response in each group.
RESULTS: In the young subjects, isometric handgrip increased heart rate and mean arterial pressure (25 ± 12 bpm and 26 ± 17 mmHg, respectively), whereas E/e' changed minimally (0.6 ± 0.9). In the elderly subjects, heart rate and mean arterial pressure were similarly increased with isometric handgrip (19 ± 16 bpm and 25 ± 11 mmHg, respectively), whereas E/e' increased more dramatically (2.3 ± 1.7). Remarkably, 11 of the 17 elderly subjects had an abnormal diastolic response (ΔE/e': 3.4 ± 1.1), whereas the remaining 6 elderly subjects showed very little change (ΔE/e': 0.3 ± 0.7), independent of age or the change in myocardial oxygen demand.
CONCLUSIONS: IHE is a simple, effective tool for evaluating diastolic function during simulated activities of daily living.

PMID: 29247511 [PubMed - indexed for MEDLINE]

Lifelong Physical Activity Regardless of Dose Is Not Associated With Myocardial Fibrosis

Fri, 12/02/2016 - 05:00

Circ Cardiovasc Imaging. 2016 Nov;9(11):e005511. doi: 10.1161/CIRCIMAGING.116.005511.


BACKGROUND: Recent reports have suggested that long-term, intensive physical training may be associated with adverse cardiovascular effects, including the development of myocardial fibrosis. However, the dose-response association of different levels of lifelong physical activity on myocardial fibrosis has not been evaluated.

METHODS AND RESULTS: Seniors free of major chronic illnesses were recruited from predefined populations based on the consistent documentation of stable physical activity over >25 years and were classified into 4 groups by the number of sessions/week of aerobic activities ≥30 minutes: sedentary (group 1), <2 sessions; casual (group 2), 2 to 3 sessions; committed (group 3), 4 to 5 sessions; and Masters athletes (group 4), 6 to 7 sessions plus regular competitions. All subjects underwent cardiopulmonary exercise testing and cardiac magnetic resonance imaging, including late gadolinium enhancement assessment of fibrosis. Ninety-two subjects (mean age 69 years, 27% women) were enrolled. No significant differences in age or sex were seen between groups. Median peak oxygen uptake was 25, 26, 32, and 40 mL/kg/min for groups 1, 2, 3, and 4, respectively. Cardiac magnetic resonance imaging demonstrated increasing left ventricular end-diastolic volumes, end-systolic volumes, stroke volumes, and masses with increasing doses of lifelong physical activity. One subject in group 2 had late gadolinium enhancement in a noncoronary distribution, and no subjects in groups 3 and 4 had evidence of late gadolinium enhancement.

CONCLUSIONS: A lifelong history of consistent physical activity, regardless of dose ranging from sedentary to competitive marathon running, was not associated with the development of focal myocardial fibrosis.

PMID:27903541 | PMC:PMC5137797 | DOI:10.1161/CIRCIMAGING.116.005511

Heart Failure: Exercise-Based Cardiac Rehabilitation: Who, When, and How Intense?

Tue, 10/04/2016 - 05:00

Can J Cardiol. 2016 Oct;32(10 Suppl 2):S382-S387. doi: 10.1016/j.cjca.2016.06.001. Epub 2016 Jun 6.


The primary chronic symptom in patients with clinically stable heart failure (HF) is reduced exercise tolerance, measured as decreased peak aerobic power (peak oxygen consumption [Vo2]), and is associated with reduced quality of life and survival. Exercise-based cardiac rehabilitation (EBCR) is a safe and effective intervention to improve peak Vo2, muscle strength, physical functional performance, and quality of life and is associated with a reduction in overall and HF-specific hospitalization in clinically stable patients with HF. Despite these salient benefits, fewer than one-tenth of eligible patients with HF are referred for EBCR after hospitalization. In this review, selection for and timing of EBCR for patients with HF, as well as exercise prescription guidelines with special emphasis on the optimal exercise training intensity to improve peak Vo2, are discussed.

PMID:27692119 | DOI:10.1016/j.cjca.2016.06.001

Heart rate, blood pressure and repolarization effects of an energy drink as compared to coffee

Thu, 03/03/2016 - 05:00

Clin Physiol Funct Imaging. 2017 Nov;37(6):675-681. doi: 10.1111/cpf.12357. Epub 2016 Mar 1.


The goal of this study was to investigate the impact of energy drinks on haemodynamic and cardiac physiology. Comparisons were made to coffee as well as water consumption. In Protocol #1 the caffeine content was normalized to body weight to represent a controlled environment. Heart rate, blood pressure and cardiac QTc interval were assessed in 15 participants, on 4 days, prior to and for 6·5 h postconsumption of (i) energy drink (2 mg caffeine per kg body weight; low dose), (ii) energy drink (3 mg caffeine per kg body weight; medium dose), (iii) coffee (2 mg caffeine per kg body weight) and (iv) 250 ml water. In Protocol #2, the beverages were consumed in volumes that they are purchased to represent real-life conditions. The aforementioned measurements were repeated in 15 participants following (i) 1 16 oz can of energy drink (16 oz Monster), (ii) 1 24 oz can of energy drink (24 oz Monster), (iii) 1 packet of Keurig K-Cup Starbucks coffee (coffee) and (iv) 250 ml water. The order of the beverages was performed in a randomized double-blinded fashion. For both protocols, QTc interval, heart rate and systolic blood pressure were unchanged in any condition (P>0·05). Diastolic blood pressure and mean blood pressure were slightly elevated in Protocol #1 (P<0·05, main effect of time) with no difference between beverages (P<0·05, interaction of beverage × time); however, they were unaffected in Protocol #2 (P>0·05). These findings suggest that acute consumption of these commonly consumed beverages has no negative effect on cardiac QTc interval.

PMID:26931509 | DOI:10.1111/cpf.12357

Impact of lifelong exercise "dose" on left ventricular compliance and distensibility

Sat, 09/20/2014 - 05:00

J Am Coll Cardiol. 2014 Sep 23;64(12):1257-66. doi: 10.1016/j.jacc.2014.03.062.


BACKGROUND: Sedentary aging has deleterious effects on the cardiovascular system, including decreased left ventricular compliance and distensibility (LVCD). Conversely, Masters level athletes, who train intensively throughout adulthood, retain youthful LVCD.

OBJECTIVES: The purpose of this study was to test the hypothesis that preservation of LVCD may be possible with moderate lifelong exercise training.

METHODS: Healthy seniors (n = 102) were recruited from predefined populations, screened for lifelong patterns of exercise training, and stratified into 4 groups: "sedentary" (<2 sessions/week); "casual" (2 to 3 sessions/week); "committed" (4 to 5 sessions/week); and "competitive" Masters level athletes (6 to 7 sessions/week). Right heart catheterization and echocardiography were performed while preload was manipulated using lower body negative pressure and rapid saline infusion to define LV pressure-volume relationships and Frank-Starling curves.

RESULTS: Peak oxygen uptake and LV mass increased with escalating doses of lifelong exercise, with little change in systolic function. At baseline, LV distensibility was greater in committed (21%) and competitive (36%) exercisers than in sedentary subjects. Group LV stiffness constants (sedentary: 0.062 ± 0.039; casual: 0.079 ± 0.052; committed: 0.055 ± 0.033; and competitive: 0.035 ± 0.033) revealed: 1) increased stiffness in sedentary subjects compared to competitive athletes, whereas lifelong casual exercise had no effect; and 2) greater compliance in committed exercisers than in sedentary or casual exercisers.

CONCLUSIONS: Low doses of casual, lifelong exercise do not prevent the decreased compliance and distensibility observed with healthy, sedentary aging. In contrast, 4 to 5 exercise sessions/week throughout adulthood prevent most of these age-related changes. As LV stiffening has been implicated in the pathophysiology of many cardiovascular conditions affecting the elderly, this "dose" of exercise training may have important implications for prevention of cardiovascular disease.

PMID:25236519 | PMC:PMC4272199 | DOI:10.1016/j.jacc.2014.03.062

Echocardiographic indices do not reliably track changes in left-sided filling pressure in healthy subjects or patients with heart failure with preserved ejection fraction

Wed, 07/27/2011 - 05:00

Circ Cardiovasc Imaging. 2011 Sep;4(5):482-9. doi: 10.1161/CIRCIMAGING.110.960575. Epub 2011 Jul 25.


BACKGROUND: In select patient populations, Doppler echocardiographic indices may be used to estimate left-sided filling pressures. It is not known, however, whether changes in these indices track changes in left-sided filling pressures within individual healthy subjects or patients with heart failure with preserved ejection fraction (HFpEF). This knowledge is important because it would support, or refute, the serial use of these indices to estimate changes in filling pressures associated with the titration of medical therapy in patients with heart failure.

METHODS AND RESULTS: Forty-seven volunteers were enrolled: 11 highly screened elderly outpatients with a clear diagnosis of HFpEF, 24 healthy elderly subjects, and 12 healthy young subjects. Each patient underwent right heart catheterization with simultaneous transthoracic echo. Pulmonary capillary wedge pressure (PCWP) and key echo indices (E/e' and E/Vp) were measured at two baselines and during 4 preload altering maneuvers: lower body negative pressure -15 mm Hg; lower body negative pressure -30 mm Hg; rapid saline infusion of 10 to 15 mL/kg; and rapid saline infusion of 20 to 30 mL/kg. A random coefficient mixed model regression of PCWP versus E/e' and PCWP versus E/Vp was performed for (1) a composite of all data points and (2) a composite of all data points within each of the 3 groups. Linear regression analysis was performed for individual subjects. With this protocol, PCWP was manipulated from 0.8 to 28.8 mm Hg. For E/e', the composite random effects mixed model regression was PCWP=0.58×E/e'+7.02 (P<0.001), confirming the weak but significant relationship between these 2 variables. Individual subject linear regression slopes (range, -6.76 to 11.03) and r(2) (0.00 to 0.94) were highly variable and often very different than those derived for the composite and group regressions. For E/Vp, the composite random coefficient mixed model regression was PCWP=1.95×E/Vp+7.48 (P=0.005); once again, individual subject linear regression slopes (range, -16.42 to 25.39) and r(2) (range, 0.02 to 0.94) were highly variable and often very different than those derived for the composite and group regressions.

CONCLUSIONS: Within individual subjects the noninvasive indices E/e' and E/Vp do not reliably track changes in left-sided filling pressures as these pressures vary, precluding the use of these techniques in research studies with healthy volunteers or the titration of medical therapy in patients with HFpEF.

PMID:21788358 | PMC:PMC3205913 | DOI:10.1161/CIRCIMAGING.110.960575