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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

Abstract
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 (ml.kg-1 ) 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

Abstract
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

Abstract
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

Abstract
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]