ORCID Profile
0000-0003-1638-1699
Current Organisation
The University of Auckland
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Publisher: American Physiological Society
Date: 04-2201
DOI: 10.1152/JAPPLPHYSIOL.00342.2013
Abstract: An increased “dose” of endurance exercise training is associated with a greater maximal oxygen uptake (V̇o 2max ), a larger left ventricular (LV) mass, and improved heart rate and blood pressure control. However, the effect of lifelong exercise dose on metabolic and hemodynamic response during exercise has not been previously examined. We performed a cross-sectional study on 101 (69 men) seniors (60 yr and older) focusing on lifelong exercise frequency as an index of exercise dose. These included 27 who had performed ≤2 exercise sessions/wk (sedentary), 25 who performed 2–3 sessions/wk (casual), 24 who performed 4–5 sessions/wk (committed) and 25 who performed ≥6 sessions/wk plus regular competitions (Masters athletes) over at least the last 25 yr. Oxygen uptake and hemodynamics [cardiac output, stroke volume (SV)] were collected at rest, two levels of steady-state submaximal exercise, and maximal exercise. Doppler ultrasound measures of LV diastolic filling were assessed at rest and during LV loading (saline infusion) to simulate increased LV filling. Body composition, total blood volume, and heart rate recovery after maximal exercise were also examined. V̇o 2max increased in a dose-dependent manner ( P 0.05). At maximal exercise, cardiac output and SV were largest in committed exercisers and Masters athletes ( P 0.05), while arteriovenous oxygen difference was greater in all trained groups ( P 0.05). At maximal exercise, effective arterial elastance, an index of ventricular-arterial coupling, was lower in committed exercisers and Masters athletes ( P 0.05). Doppler measures of LV filling were not enhanced at any condition, irrespective of lifelong exercise frequency. These data suggest that performing four or more weekly endurance exercise sessions over a lifetime results in significant gains in V̇o 2max , SV, and heart rate regulation during exercise however, improved SV regulation during exercise is not coupled with favorable effects on LV filling, even when the heart is fully loaded.
Publisher: American Physiological Society
Date: 12-2014
DOI: 10.1152/JAPPLPHYSIOL.00395.2014
Abstract: Abnormal heart rate recovery (HRR) after maximal exercise may indicate autonomic dysfunction and is a predictor for cardiovascular mortality. HRR is attenuated with aging and in middle-age hypertensive patients, but it is unknown whether HRR is attenuated in older-age adults with hypertension. This study compared HRR among 16 unmedicated stage 1 hypertensive (HTN) participants [nine men/seven women 68 ± 5 (SD) yr awake ambulatory blood pressure (BP) 149 ± 10/87 ± 7 mmHg] and 16 normotensive [control (CON)] participants (nine men/seven women 67 ± 5 yr 122 ± 4/72 ± 5 mmHg). HR, BP, oxygen uptake (V̇o 2 ), cardiac output (Qc), and stroke volume (SV) were measured at rest, at two steady-state work rates, and graded exercise to peak during maximal treadmill exercise. During 6 min of seated recovery, the change in HR (ΔHR) was obtained every minute and BP every 2 min. In addition, HRR and R-R interval (RRI) recovery kinetics were analyzed using a monoexponential function, and the indexes (HRR I and RRI I ) were calculated. Maximum V̇o 2 , HR, Qc, and SV responses during exercise were not different between groups. ΔHR was significantly different ( P 0.001) between the HTN group (26 ± 8) and the CON group (36 ± 12 beats/min) after 1 min of recovery but less convincing at 2 min ( P = 0.055). BP recovery was similar between groups. HRR I was significantly lower ( P = 0.016), and there was a trend of lower RRI I ( P = 0.066) in the HTN group compared with the CON group. These results show that in older-age adults, HRR is attenuated further with the presence of hypertension, which may be attributable to an impairment of autonomic function.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2006
Publisher: Oxford University Press (OUP)
Date: 15-11-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2013
DOI: 10.1161/CIRCIMAGING.113.000565
Abstract: Aging and sedentary lifestyles lead to cardiac atrophy, ventricular stiffening, and impaired diastolic function. Both conditions are marked by increased adiposity, which can lead to ectopic fat deposition in nonadipocyte tissues including the myocardium. The effect of excess intramyocardial fat on cardiac function in nonobese in iduals is unknown. Cardiac lipid content was measured by magnetic resonance spectroscopy in 153 healthy nonobese subjects with varying fitness levels quantified by peak oxygen uptake during treadmill exercise. Cardiac function (echo) and left ventricular (LV) filling pressures (right heart catheterization) were measured under varying preloads. LV stiffness was calculated from a curve fit of the diastolic portion of the pressure–volume curve. The strongest clinical predictors of lipid content were body mass index (β=+0.03 95% confidence interval, 0.001–0.06) and peak oxygen uptake (β=−0.02 95% confidence interval, −0.03 to −0.009 R 2 =0.14 P .001). Subjects in the highest quintile had smaller LV end-diastolic volumes (68±13 versus 58±12 mL/m 2 P .01) and decreased peak early mitral annular and increased peak late mitral inflow velocities. There were no differences in LV stiffness, but a leftward shift in the pressure–volume curve suggested a less distensible ventricle with increasing myocardial lipid levels. After adjusting for age, fitness, and body mass index, echocardiographic and morphometric differences among groups were attenuated and no longer significant. Body mass index and fitness levels are the strongest predictors of myocardial lipid content in nonobese humans. Cardiac lipid content is associated with decreased ventricular distensibility, and it may provide a causal mechanism linking changes in LV function related to age and fitness.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2018
Publisher: Springer Science and Business Media LLC
Date: 17-01-2007
DOI: 10.1007/S00421-006-0384-5
Abstract: The shift from upright to supine posture increases stroke volume in healthy young adults, primarily through increased end-diastolic volume. Aging is associated with increased ventricular stiffness and impaired diastolic function. The purpose of this study was to determine whether the stroke volume change between the upright and supine posture was blunted in healthy older men and whether the early mitral inflow response to this postural change was reduced by aging. Pulsed Doppler echocardiography and tissue Doppler imaging were used to assess stroke volume and left ventricular function during upright and supine posture in 10 young and 12 older healthy men. Cardiac output was greater in the supine versus upright condition in both groups. In young men supine posture was associated with a large increment in stroke volume (63.1 +/- 7.2 upright to 98.6 +/- 11.7 ml supine P < 0.05) and a decrease in heart rate. In older men, the stroke volume increment was smaller (63.9 +/- 3.6 upright to 82.0 +/- 5.7 ml supine P < 0.05) and heart rate decreased less than young men when comparing upright to supine posture. Increased stroke volume was associated with higher peak early diastolic filling velocity (E) in young men and higher peak late diastolic filling velocity (A) in older men. These findings indicate that healthy aging attenuates the increase in early filling associated with moving from an upright to a supine posture. Furthermore, healthy older men are more dependent upon atrial diastolic filling to augment end-diastolic and stroke volume, which may be due to age-associated increases in left ventricular filling pressure and impaired compliance.
Publisher: Springer Science and Business Media LLC
Date: 19-01-2018
DOI: 10.1007/S11136-018-1784-9
Abstract: To quantify the relationship between the change in exercise dose and health-related quality of life (HRQoL) in a cohort of patients participating in a community-based phase-3 cardiac rehabilitation (CR) program. A retrospective, pre-experimental (no control group) design of 58 participants that completed a phase-3, 12-week exercise-based CR program was used to test the current hypothesis. Self-reported HRQoL (36-Item Short Form Health Survey Version 2, SF-36v2) was assessed prior and after completing the CR program. The change in exercise dose was estimated from the assigned training load in weeks 1 and 12 of the CR program. A series of regression models were fitted to ascertain the relationship between the change in exercise dose and changes in the SF-36v2. There was a strong quadratic trend between the change in exercise dose and the mean change in SF-36 Mental and Physical Health Summary Scores. Analysis of covariance showed that the mean changes in the SF-36 Summary Scores statistically fluctuate across quartiles of exercise dose. The data show that there is a threshold amount of increase in exercise (Q The current findings suggest that physical and mental health-related quality of life are improved with a phase-3 CR program. The dose-response relationship observed indicates that a threshold exercise dose is required to improve HRQoL, and that larger doses of exercise do not confer further improvements in HRQoL.
Publisher: Wiley
Date: 29-05-2015
DOI: 10.1113/JP270280
Publisher: Elsevier BV
Date: 09-2017
Publisher: Wiley
Date: 07-11-2012
DOI: 10.1113/EXPPHYSIOL.2012.067488
Abstract: A marked reduction in upright stroke volume (SV) contributes substantially to orthostatic intolerance after exposure to spaceflight or bed rest. It is unclear whether slowed left ventricular (LV) relaxation and diastolic suction contribute to the reduction in SV or whether these changes are influenced by exercise training while in bed. Twenty-seven healthy adults completed 5 weeks of -6 deg head-down bed rest (HDBR). During HDBR, nine subjects were sedentary (NOEX), while 18 performed near-daily rowing ergometry (EX). Left ventricular mass, SV, LV end-diastolic volume (LVEDV), pulmonary capillary wedge pressure and Doppler ultrasound indices of LV function were collected pre- and post-HDBR during supine rest (twice) and during reduced LV loading (lower body negative pressure LBNP) and increased LV loading (saline infusion). Post-HDBR, LV mass increased in the EX group, but decreased in the NOEX group. The reduction in SV and LVEDV during supine rest and LBNP were greater with NOEX in comparison to EX after HDBR. Peak early mitral annular velocity, isovolumic relaxation time, early propagation velocity, a non-invasive index of early diastolic filling and ventricular diastolic suction, and peak global longitudinal early strain rate were slowed during supine rest after HDBR with NOEX however, these variables were either unaltered or the reduction was less prominent with EX. Doppler ultrasound measures of early diastolic filling, ventricular relaxation and diastolic suction were not significantly affected during LV unloading by LBNP after HDBR in either group. All Doppler indices were restored to pre-HDBR levels in both groups during saline infusion to normalize LV filling pressure after HDBR. It is concluded that Doppler indices of dynamic LV filling were reduced in both groups after HDBR however, these effects were more pronounced in the NOEX group. Irrespective of group, post-HDBR Doppler parameters were restored when LV filling pressure was increased to pre-HDBR levels during saline infusion. Therefore, the reduction in upright SV after HDBR is more influenced by changes in LV loading conditions, namely left atrial pressure in the setting of LV remodelling, rather than ventricular relaxation and diastolic suction.
Publisher: Wiley
Date: 21-05-2020
DOI: 10.1113/JP278503
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.AMJCARD.2011.10.010
Abstract: The Fick principle (cardiac output [Q(c)] = oxygen uptake [Vo(2)]/arteriovenous oxygen difference) can be used to calculate Q(c), with VO(2) frequently estimated by derived equations. To compare the accuracy of measured versus estimated VO(2), data were analyzed from 2 studies in which VO(2) at rest was measured using the Douglas bag technique. One study comprised adults with diabetes, and the other was an exercise study of healthy adults. VO(2) at rest was estimated as VO(2) (ml/min) = 125 ml/min/m(2) × body surface area (m(2)), with sensitivity analyses evaluating 2 other commonly used equations. Mean absolute difference (milliliters per minute) and ordinary least products regression were used to assess agreement between measured and estimated VO(2). Overall, mean measured versus estimated VO(2) differed significantly (307.2 ± 75.2 vs 259.9 ± 36.7 ml/min, p <0.0001), with a mean absolute difference of 52.9 ± 43.2 ml/min (p 25% from the measured VO(2). Mean absolute difference increased from 36.7 ml/min in the lowest body mass index group (<25 kg/m(2)) to 91.7 ml/min in the highest group (≥40 kg/m(2)) (p for trend = 0.001) and was significantly higher in men than in women (65.6 vs 33.9 ml/min, p = 0.001) error was similar by median-split age (p = 0.65) and race (p = 0.34). Similar results were obtained when evaluating each of the other 2 estimating equations. Estimation of VO(2) at rest is inaccurate, especially in men and with increasing adiposity. In conclusion, when clinical hemodynamic assessment is performed, VO(2) should be measured, not estimated.
Publisher: American Physiological Society
Date: 05-2020
DOI: 10.1152/JAPPLPHYSIOL.00458.2019
Abstract: Women are at increased risk for heart failure with preserved ejection fraction (HFpEF) largely due to higher prevalence of arterial and cardiac stiffening. We were able to identify several subclinical markers of early (stages A and B) HFpEF pathophysiology largely on the basis of exercise blood pressure (BP) response in otherwise healthy middle-aged women. Exercise BP response may be an inexpensive screening tool to identify women at highest risk for developing future HFpEF.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2016
DOI: 10.1161/CIRCIMAGING.116.005511
Abstract: 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. Seniors free of major chronic illnesses were recruited from predefined populations based on the consistent documentation of stable physical activity over years and were classified into 4 groups by the number of sessions/week of aerobic activities ≥30 minutes: sedentary (group 1), 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. 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.
Publisher: American Physiological Society
Date: 05-2011
DOI: 10.1152/AJPHEART.01198.2010
Abstract: Pericardial constraint and ventricular interaction influence left ventricular (LV) performance when preload is high. However, it is unclear if these constraining forces modulate LV filling when the heart is unloaded, such as during upright posture, in humans. Fifty healthy in iduals underwent right heart catheterization to measure pulmonary capillary wedge (PCWP) and right atrial pressure (RAP). To evaluate the effects of pericardial constraint on hemodynamics, transmural filling pressure (LVTMP) was defined as PCWP-RAP. Beat-to-beat blood pressure (BP) waveforms were recorded, and stroke volume (SV) was derived from the Modelflow method. After measurements at −30 mmHg lower body negative pressure (LBNP), which approximates the upright position, LBNP was released, and beat-to-beat measurements were performed for 15 heartbeats. At −30 mmHg LBNP, RAP and PCWP were significantly decreased. During the first six beats of LBNP release, heart rate (HR) was unchanged, while BP increased from the fourth beat. RAP increased faster than PCWP resulting in an acute decrease in LVTMP from the fourth beat. A corresponding drop in SV by 3% was observed with no change in pulse pressure. From the 7th to 15th beats, LVTMP and SV increased steadily, followed by a decreased HR due to the baroreflex. A decreased TMP, but not PCWP, caused a transient drop in SV with no changes in HR or pulse pressure during LBNP release. These results suggest that the pericardium constrains LV filling during LBNP release, enough to cause a small but significant drop of SV, even at low cardiac filling pressure in healthy humans.
Publisher: Wiley
Date: 19-04-2012
DOI: 10.1111/J.1748-1716.2012.02430.X
Abstract: To determine whether the larger exercise stroke volume in senior endurance-trained athletes results from an attenuation of age-related alterations in left ventricular (LV) early diastolic filling or a more vigorous late filling. Body composition (DEXA), VO(2)peak, stroke volume (CO(2) rebreathing) and Doppler measures of early and late mitral inflow and mitral annular velocities were collected at seated upright rest and heart rate-matched exercise (100 and 120 bpm) in trained and untrained younger (18-30 years) men and trained and untrained older (60-80 years) healthy men. Ageing had a greater effect than training status on seated rest mitral inflow and tissue Doppler imaging parameters, as shown by a lower peak early-to-late mitral inflow velocity ratio (E/A ratio) and slower peak early mitral annular velocity (Em) in older compared with younger men. Exercise stroke volume was unaffected by healthy ageing however, Em, an index of early LV lengthening rate and relaxation, was slower (P < 0.001), while measures of atrial systole were increased (P < 0.001) during exercise in older men. Stroke volume during exercise was larger in the trained men (P < 0.001) however, early and late mitral inflow and tissue velocities were not different between trained and untrained men. The larger exercise stroke volume in trained older male athletes does not seem to be related to faster filling or lengthening velocities during early or late filling. Thus, a larger, more compliant left ventricle in combination with an increased blood volume may explain the larger LV filling volumes in trained seniors.
Publisher: American Physiological Society
Date: 08-2012
DOI: 10.1152/AJPHEART.00142.2012
Abstract: Doppler ultrasound measures of left ventricular (LV) active relaxation and diastolic suction are slowed with healthy aging. It is unclear to what extent these changes are related to alterations in intrinsic LV properties and/or cardiovascular loading conditions. Seventy carefully screened in iduals (38 female, 32 male) aged 21–77 were recruited into four age groups (young: early middle age: 35–49 late middle age: 50–64 and seniors: ≥65 yr). Pulmonary capillary wedge pressure (PCWP), stroke volume, LV end-diastolic volume, and Doppler measures of LV diastolic filling were collected at multiple loading conditions, including supine baseline, lower body negative pressure to reduce LV filling, and saline infusion to increase LV filling. LV mass, supine PCWP, and heart rate were not affected significantly by aging. Measures of LV relaxation, including isovolumic relaxation time and the time constant of isovolumic pressure decay increased progressively, whereas peak early mitral annular longitudinal velocity decreased with advancing age ( P 0.001). The propagation velocity of early mitral inflow, a noninvasive measure of LV suction, decreased with aging with the greatest reduction in seniors ( P 0.001). Age-related differences in LV relaxation and diastolic suction were not attenuated significantly when PCWP was increased in older subjects or reduced in the younger subjects. There is an early slowing of LV relaxation and diastolic suction beginning in early middle age, with the greatest reduction observed in seniors. Because age-related differences in LV dynamic diastolic filling parameters were not diminished significantly with significant changes in LV loading conditions, a decline in ventricular relaxation is likely responsible for the alterations in LV diastolic filling with senescence.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2012
DOI: 10.1161/CIRCULATIONAHA.112.111302
Abstract: Hemodynamic assessment after volume challenge has been proposed as a way to identify heart failure with preserved ejection fraction. However, the normal hemodynamic response to a volume challenge and how age and sex affect this relationship remain unknown. Sixty healthy subjects underwent right heart catheterization to measure age- and sex-related normative responses of pulmonary capillary wedge pressure and mean pulmonary arterial pressure to volume loading with rapid saline infusion (100–200 mL/min). Hemodynamic responses to saline infusion in heart failure with preserved ejection fraction (n=11) were then compared with those of healthy young ( years of age) and older (≥50 years of age) subjects. In healthy subjects, pulmonary capillary wedge pressure increased from 10±2 to 16±3 mm Hg after ~1 L and to 20±3 mm Hg after ~2 L of saline infusion. Older women displayed a steeper increase in pulmonary capillary wedge pressure relative to volume infused (16±4 mm Hg·L −1 ·m 2 ) than the other 3 groups ( P ≤0.019). Saline infusion resulted in a greater increase in mean pulmonary arterial pressure relative to cardiac output in women compared with men regardless of age. Subjects with heart failure with preserved ejection fraction exhibited a steeper increase in pulmonary capillary wedge pressure relative to infused volume (25±12 mm Hg·L −1 ·m 2 ) than healthy young and older subjects ( P ≤0.005). Filling pressures rise significantly with volume loading, even in healthy volunteers. Older women and patients with heart failure with preserved ejection fraction exhibit the largest increases in pulmonary capillary wedge pressure and mean pulmonary arterial pressure.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2013
DOI: 10.1161/CIRCHEARTFAILURE.113.000440
Abstract: Lifelong exercise training maintains a youthful compliance of the left ventricle (LV), whereas a year of exercise training started later in life fails to reverse LV stiffening, possibly because of accumulation of irreversible advanced glycation end products. Alagebrium breaks advanced glycation end product crosslinks and improves LV stiffness in aged animals. However, it is unclear whether a strategy of exercise combined with alagebrium would improve LV stiffness in sedentary older humans. Sixty-two healthy subjects were randomized into 4 groups: sedentary+placebo sedentary+alagebrium (200 mg/d) exercise+placebo and exercise+alagebrium. Subjects underwent right heart catheterization to define LV pressure–volume curves secondary functional outcomes included cardiopulmonary exercise testing and arterial compliance. A total of 57 of 62 subjects (67±6 years 37 f/20 m) completed 1 year of intervention followed by repeat measurements. Pulmonary capillary wedge pressure and LV end-diastolic volume were measured at baseline, during decreased and increased cardiac filling. LV stiffness was assessed by the slope of LV pressure–volume curve. After intervention, LV mass and end-diastolic volume increased and exercise capacity improved (by ≈8%) only in the exercise groups. Neither LV mass nor exercise capacity was affected by alagebrium. Exercise training had little impact on LV stiffness (training×time effect, P =0.46), whereas alagebrium showed a modest improvement in LV stiffness compared with placebo (medication×time effect, P =0.04). Alagebrium had no effect on hemodynamics, LV geometry, or exercise capacity in healthy, previously sedentary seniors. However, it did show a modestly favorable effect on age-associated LV stiffening. URL: www.clinicaltrials.gov . Unique identifier: NCT01014572.
Publisher: MDPI AG
Date: 19-05-2019
Abstract: We sought to determine if there was an intergenerational association between parental weight, cardiorespiratory fitness (CRF), and disease status, with the prevalence of metabolic syndrome (MetSyn) in their young adult offspring. Young adults (n = 270, 21 ± 1 years, 53.3% female) were assessed for MetSyn and self-reported parent’s CRF, body mass status, and disease status. MetSyn was present in 11.9% of participants, 27.4% had one or two components, and 58.5% had no components. A significantly higher percentage (93.9%) of young adults with MetSyn identified at least one parent as being overweight or obese, 84.8% reported low parental CRF and 87.9% reported a parent with disease (all p 0.017). MetSyn in offspring is more likely when parents are perceived to have low CRF, increased body mass, and a diagnosis of disease. Evaluating the offspring of people with low CRF, elevated body mass, or who have a history of cardiovascular disease (CVD) or diabetes should be considered to promote early identification and treatment of young adults to reduce future premature CVD in these at-risk in iduals.
Publisher: Annual Reviews
Date: 27-01-2021
DOI: 10.1146/ANNUREV-MED-070119-115343
Abstract: The global population is rapidly aging, with predictions of many more people living beyond 85 years. Age-related physiological adaptations predispose to decrements in physical function and functional capacity, the rate of which can be accelerated by chronic disease and prolonged physical inactivity. Decrements in physical function exacerbate the risk of chronic disease, disability, dependency, and frailty with advancing age. Regular exercise positively influences health status, physical function, and disease risk in adults of all ages. Herein, we review the role of structured exercise training in the oldest old on cardiorespiratory fitness and muscular strength and power, attributes critical for physical function, mobility, and independent living.
Publisher: Wiley
Date: 30-05-2018
DOI: 10.1113/JP275301
Publisher: Wiley
Date: 14-03-2012
Publisher: Elsevier BV
Date: 08-2019
No related grants have been discovered for Graeme Carrick-Ranson.