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Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche., (© 2024. The Author(s).)

Background: The extent of structural cardiac remodeling in response to endurance training is maturity dependent. In adults, this structural adaptation is often associated with the adaptation of left ventricular (LV) twist mechanics. For example, an increase in LV twist often follows an expansion in end-diastolic volume, whereas a reduction in twist may follow a thickening of the LV walls. While structural cardiac remodeling has been shown to be more prominent post-peak height velocity (PHV), it remains to be determined how this maturation-dependent structural remodeling influences LV twist. Therefore, we aimed to (1) compare LV twist mechanics between trained and untrained children pre- and post-PHV and (2) investigate how LV structural variables relate to LV twist mechanics pre- and post-PHV., Methods: Left ventricular function and morphology were assessed (echocardiography) in endurance-trained and untrained boys (n = 38 and n = 28, respectively) and girls (n = 39 and n = 34, respectively). Participants were categorized as either pre- or post-PHV using maturity offset to estimate somatic maturation., Results: Pre-PHV, there were no differences in LV twist or torsion between trained and untrained boys (twist: P = .630; torsion: P = .382) or girls (twist: P = .502; torsion: P = .316), and LV twist mechanics were not related with any LV structural variables (P > .05). Post-PHV, LV twist was lower in trained versus untrained boys (P = .004), with torsion lower in trained groups, irrespective of sex (boys: P < .001; girls: P = .017). Moreover, LV torsion was inversely related to LV mass (boys: r = -0.55, P = .001; girls: r = -0.46, P = .003) and end-diastolic volume (boys: r = -0.64, P < .001; girls: r = -0.36, P = .025) in both sexes., Conclusions: A difference in LV twist mechanics between endurance-trained and untrained cohorts is only apparent post-PHV, where structural and functional remodeling were related., Competing Interests: Conflicts of Interest None., (Copyright © 2023 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.)

Central arterial stiffness can influence exercise blood pressure (BP) by increasing the rise in arterial pressure per unit increase in aortic inflow. Whether central arterial stiffness influences the pressor response to isometric handgrip exercise (HG) and post-exercise muscle ischemia (PEMI), two common laboratory tests to study sympathetic control of BP, is unknown. We studied 46 healthy non-hypertensive males (23 young and 23 middle-aged) during HG (which increases in cardiac output [Q̇c]) and isolated metaboreflex activation PEMI (no change or decreases in Q̇c). Aortic stiffness (aortic pulse wave velocity [aPWV]; applanation tonometry via SphygmoCor) was measured during supine rest and was correlated to the pressor responses to HG and PEMI. BP (photoplethysmography) and muscle sympathetic nerve activity (MSNA) were continuously recorded at rest, during HG to fatigue (35 % maximal voluntary contraction) and 2-min of PEMI. aPWV was higher in middle-aged compared to young males (7.1 ± 0.9 vs 5.4 ± 0.7 m/s, P < 0.001). Middle-aged males also exhibited greater increases in systolic pressure (∆30 ± 11 vs 10 ± 8 mmHg) and MSNA (∆2313 ± 2006 vs 1387 ± 1482 %/min) compared to young males during HG (both, P < 0.03); with no difference in the Q̇c response (P = 0.090). Responses to PEMI were not different between groups. Sympathetic transduction during these stressors (MSNA-diastolic pressure slope) was not different between groups (P > 0.341). Middle-aged males displayed a greater increase in SBP per unit change of Q̇c during HG (∆SBP/∆Q̇c; 21 ± 18 vs 6 ± 10 mmHg/L/min, P = 0.004), with a strong and moderate relationship between the change in systolic (r = 0.53, P < 0.001) and diastolic pressure (r = 0.34, P = 0.023) and resting aPWV, respectively; with no correlation during PEMI. Central arterial stiffness can modulate pressor responses during stimuli associated with increases in cardiac output and sympathoexcitation in healthy males., Competing Interests: Declaration of competing interest Not applicable., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Purpose: We determined the effect of habitual endurance exercise and age on aortic pulse wave velocity (aPWV), augmentation pressure (AP) and systolic blood pressure (aSBP), with statistical adjustments of aPWV and AP for heart rate and aortic mean arterial pressure, when appropriate. Furthermore, we assessed whether muscle sympathetic nerve activity (MSNA) correlates with AP in young and middle-aged men., Methods: Aortic PWV, AP, aortic blood pressure (applanation tonometry; SphygmoCor) and MSNA (peroneal microneurography) were recorded in 46 normotensive men who were either young or middle-aged and endurance-trained runners or recreationally active nonrunners (10 nonrunners and 13 runners within each age-group). Between-group differences and relationships between variables were assessed via ANOVA/ANCOVA and Pearson product-moment correlation coefficients, respectively., Results: Adjusted aPWV and adjusted AP were similar between runners and nonrunners in both age groups (all, P > 0.05), but higher with age (all, P < 0.001), with a greater effect size for the age-related difference in AP in runners (Hedges' g, 3.6 vs 2.6). aSBP was lower in young (P = 0.009; g = 2.6), but not middle-aged (P = 0.341; g = 1.1), runners compared to nonrunners. MSNA burst frequency did not correlate with AP in either age group (young: r = 0.00, P = 0.994; middle-aged: r = - 0.11, P = 0.604)., Conclusion: There is an age-dependent effect of habitual exercise on aortic haemodynamics, with lower aSBP in young runners compared to nonrunners only. Statistical adjustment of aPWV and AP markedly influenced the outcomes of this study, highlighting the importance of performing these analyses. Further, peripheral sympathetic vasomotor outflow and AP were not correlated in young or middle-aged normotensive men., (© 2022. The Author(s).)

New Findings: What is the central question of this study? Endurance athletes demonstrate altered regional right ventricular (RV) wall mechanics, characterized by lower basal deformation, in comparison to non-athletic control subjects at rest. We hypothesized that regional adaptations at the RV base reflect an enhanced functional reserve capacity in response to haemodynamic volume loading. What is the main finding and its importance? Free wall RV longitudinal strain is elevated in response to acute volume loading in both endurance athletes and control subjects. However, the RV basal segment longitudinal strain response to acute volume infusion is greater in endurance athletes. Our findings suggest that training-induced cardiac remodelling might involve region-specific adaptation in the RV functional response to volume manipulation., Abstract: Eccentric remodelling of the right ventricle (RV) in response to increased blood volume and repetitive haemodynamic load during endurance exercise is well established. Structural remodelling is accompanied by decreased deformation at the base of the RV free wall, which might reflect an enhanced functional reserve capacity in response to haemodynamic perturbation. Therefore, in this study we examined the impact of acute blood volume expansion on RV wall mechanics in 16 young endurance-trained men (aged 24 ± 3 years) and 13 non-athletic male control subjects (aged 27 ± 5 years). Conventional echocardiographic parameters and the longitudinal strain and strain rate were quantified at the basal and apical levels of the RV free wall. Measurements were obtained at rest and after 7 ml/kg i.v. Gelofusine infusion, with and without a passive leg raise. After infusion, blood volume increased by 12 ± 4 and 14 ± 5% in endurance-trained individuals versus control subjects, respectively (P = 0.264). Both endurance-trained individuals (8 ± 10%) and control subjects (7 ± 9%) experienced an increase in free wall strain from baseline, which was also similar following leg raise (7 ± 10 and 6 ± 10%, respectively; P = 0.464). However, infusion evoked a greater increase in basal longitudinal strain in endurance-trained versus control subjects (16 ± 14 vs. 6 ± 11%; P = 0.048), which persisted after leg raise (16 ± 18 vs. 3 ± 11%; P = 0.032). Apical longitudinal strain and RV free wall strain rates were not different between groups and remained unchanged after infusion across all segments. Endurance training results in a greater contribution of longitudinal myocardial deformation at the base of the RV in response to a haemodynamic volume challenge, which might reflect a greater region-specific functional reserve capacity., (© 2021 The Authors. Experimental Physiology © 2021 The Physiological Society.)

Serological assessment of cardiac troponins (cTn) is the gold standard to assess myocardial injury in clinical practice. A greater magnitude of acutely or chronically elevated cTn concentrations is associated with lower event-free survival in patients and the general population. Exercise training is known to improve cardiovascular function and promote longevity, but exercise can produce an acute rise in cTn concentrations, which may exceed the upper reference limit in a substantial number of individuals. Whether exercise-induced cTn elevations are attributable to a physiological or pathological response and if they are clinically relevant has been debated for decades. Thus far, exercise-induced cTn elevations have been viewed as the only benign form of cTn elevations. However, recent studies report intriguing findings that shed new light on the underlying mechanisms and clinical relevance of exercise-induced cTn elevations. We will review the biochemical characteristics of cTn assays, key factors determining the magnitude of postexercise cTn concentrations, the release kinetics, underlying mechanisms causing and contributing to exercise-induced cTn release, and the clinical relevance of exercise-induced cTn elevations. We will also explain the association with cardiac function, correlates with (subclinical) cardiovascular diseases and exercise-induced cTn elevations predictive value for future cardiovascular events. Last, we will provide recommendations for interpretation of these findings and provide direction for future research in this field.

Background: Structural remodeling of the right ventricle (RV) is widely documented in athletes. However, functional adaptation, including RV pressure generation and systolic free-wall longitudinal mechanics, remains equivocal. This meta-analysis compared RV pressure and function in athletes and controls., Methods: A systematic review of online databases was conducted up to June 4, 2020. Meta-analyses were performed on RV systolic pressures, at rest and during exercise, tricuspid annular plane systolic displacement, myocardial velocity (S'), and global and regional longitudinal strain. Bias was assessed using Egger regression for asymmetry. Data were analyzed using random-effects models with weighted mean difference and 95% CI., Results: Fifty-three studies were eligible for inclusion. RV systolic pressure was obtained from 21 studies at rest ( n =1043:1651; controls:athletes) and 8 studies during exercise ( n =240:495) and was significantly greater in athletes at rest (weighted mean difference, 2.9 mmHg [CI, 1.3-4.5 mmHg]; P =0.0005) and during exercise (11.0 [6.5-15.6 mm Hg]; P <0.0001) versus controls. Resting tricuspid annular plane systolic displacement ( P <0.0001) and S' ( P =0.001) were greater in athletes. In contrast, athletes had similar RV free-wall longitudinal strain (17 studies; n =450:605), compared with controls but showed greater longitudinal apical strain (16 studies; n =455:669; 0.9%, 0.1%-1.8%; P =0.03) and lower basal strain (-2.5% [-1.4 to -3.5%]; P <0.0001)., Conclusions: Functional RV adaptation, characterized by increased tricuspid annular displacement and velocity and a greater base-to-apex strain gradient, is a normal feature of the athlete's heart, together with a slightly elevated RV systolic pressure. These findings contribute to our understanding of RV in athletes and highlight the importance of considering RV function in combination with structure in the clinical interpretation of the athlete's heart.

Purpose: The increased physiological demand of pregnancy results in the profound adaptation of the maternal cardiovascular system, reflected by greater resting cardiac output and left ventricular (LV) deformation. Whether the increased resting demand alters acute cardiac responses to exercise in healthy pregnant women is not well understood., Methods: Healthy nonpregnant (n = 18), pregnant (n = 14, 22-26 wk gestation), and postpartum women (n = 13, 12-16 wk postdelivery) underwent assessments of cardiac function and LV mechanics at rest, during a sustained isometric forearm contraction (30% maximum), and during low-intensity (LOW) and moderate-intensity (MOD) dynamic cycling exercise (25% and 50% peak power output). Significant differences (α = 0.05) were determined using ANCOVA and general linear model (resting value included as covariate)., Results: When accounting for higher resting cardiac output in pregnant women, pregnant women had greater cardiac output during isometric contraction (2.0 ± 0.3 L·min-1·m-1.83; nonpregnant, 1.3 ± 0.2 L·min-1·m-1.83; postpartum, 1.5 ± 0.5 L·min-1·m-1.83; P = 0.02) but similar values during dynamic cycling exercise (pregnant, LOW = 2.8 ± 0.4 L·min-1·m-1.83, MOD = 3.4 ± 0.7 L·min-1·m-1.83; nonpregnant, LOW = 2.4 ± 0.3 L·min-1·m-1.83, MOD = 3.0 ± 0.3 L·min-1·m-1.83; postpartum, LOW = 2.3 ± 0.4 L·min-1·m-1.83, MOD = 3.0 ± 0.5 L·min-1·m-1.83; P = 0.96). Basal circumferential strain was higher in pregnant women at rest, during the sustained isometric forearm contraction (-23.5% ± 1.2%; nonpregnant, -14.6% ± 1.4%; P = 0.001), and during dynamic cycling exercise (LOW = -27.0% ± 4.9%, MOD = -27.4% ± 4.6%; nonpregnant, LOW = -15.8% ± 4.5%, MOD = -15.2% ± 6.7%; P = 0.012); however, other parameters of LV mechanics were not different between groups., Conclusion: The results support that the maternal heart can appropriately respond to additional cardiac demand and altered loading experienced during acute isometric and dynamic exercise, although subtle differences in responses to these challenges were observed. In addition, the LV mechanics that underpin global cardiac function are greater in pregnant women during exercise, leading to the speculation that the hormonal milieu of pregnancy influences regional deformation., (Copyright © 2020 by the American College of Sports Medicine.)

Measurements of intraocular pressure (IOP) and tear production are key components of ophthalmic examination. Chimpanzees ( Pan troglodytes ) were anesthetized using either tiletamine-zolazepam (TZ; 2 mg/kg) combined with medetomidine (TZM; 0.02 mg/kg), or, TZ alone (6mg/kg). Tear production was lower ( P = 0.03) with TZM (5.63 ± 6.22 mm/min; n = 16) than with TZ (11.13 ± 4.63 mm/min; n = 8). Mean IOP, measured using rebound tonometry in an upright body position ( n = 8) was 18.74 ± 3.01 mm Hg, with no differences between right and left eyes. However, positioning chimpanzees in left lateral recumbency ( n = 27) resulted in higher IOP in the dependent (left) eye (24.77 ± 4.49 mm Hg) compared to the nondependent (right) eye (22.27 ± 4.65 mm Hg) of the same animal ( P < 0.0001). These data indicate medetomidine anesthesia markedly lowers tear production in chimpanzees, and that body position should be taken into consideration when performing rebound tonometry.

Left ventricular (LV) structural remodeling following athletic training has been evidenced through training-specific changes in wall thickness and geometry. Whether the LV response to changes in hemodynamic load also adapts in a training-specific manner is unknown. Using echocardiography, we examined LV responses of endurance-trained ( n = 15), resistance-trained ( n = 14), and nonathletic men ( n = 13) to 1 ) 20, 40, and 60% one repetition-maximum (1RM), leg-press exercise and 2 ) intravascular Gelofusine infusion (7 mL/kg) with passive leg raise. While resting heart rate was lower in endurance-trained participants versus controls ( P = 0.001), blood pressure was similar between groups. Endurance-trained individuals had lower wall thickness but greater LV mass relative to body surface area versus controls, with no difference between resistance-trained individuals and controls. Leg press evoked a similar increase in blood pressure; however, resistance-trained participants preserved stroke volume (SV; -3 ± 8%) versus controls at 60% 1RM (-15 ± 7%, P = 0.001). While the maintenance of SV was related to the change in longitudinal strain across all groups ( R = 0.537; P = 0.007), time-to-peak strain was maintained in resistance-trained but delayed in endurance-trained individuals (1 vs. 12% delay; P = 0.021). Volume infusion caused a similar increase in end-diastolic volume (EDV) and SV across groups, but leg raise further increased EDV only in endurance-trained individuals (5 ± 5 to 8 ± 5%; P = 0.018). Correlation analysis revealed a relationship between SV and longitudinal strain following infusion and leg raise ( R = 0.334, P = 0.054); however, we observed no between-group differences in longitudinal myocardial mechanics. In conclusion, resistance-trained individuals better maintained SV during pressure loading, whereas endurance-trained individuals demonstrated greater EDV reserve during volume loading. These data provide novel evidence of training-specific LV functional remodeling. NEW & NOTEWORTHY Training-specific functional remodeling of the LV in response to different loading conditions has been recently suggested, but not experimentally tested in the same group of individuals. Our data provide novel evidence of a dichotomous, training-specific LV adaptive response to hemodynamic pressure or volume loading.

Changes in the arterial baroreflex arc contribute to elevated sympathetic outflow and altered reflex control of blood pressure with human aging. Using ultrasound and sympathetic microneurography (muscle sympathetic nerve activity, MSNA) we investigated the relationships between aortic and carotid artery wall tension (indices of baroreceptor activation) and the vascular sympathetic baroreflex operating point (OP; MSNA burst incidence) in healthy, normotensive young ( n = 27, 23 ± 3 yr) and middle-aged men ( n = 22, 55 ± 4 yr). In young men, the OP was positively related to the magnitude and rate of unloading and time spent unloaded in the aortic artery ( r  = 0.56, 0.65, and 0.51, P = 0.02, 0.003, and 0.03), but not related to the magnitude or rate of unloading or time spent unloaded in the carotid artery ( r  = -0.32, -0.07, and 0.06, P = 0.25, 0.81, and 0.85). In contrast, in middle-aged men, the OP was not related to either the magnitude or rate of unloading or time spent unloaded in the aortic ( r  = 0.22, 0.21, and 0.27, P = 0.41, 0.43, and 0.31) or carotid artery ( r  = 0.06, 0.28, and -0.01; P = 0.48, 0.25, and 0.98). In conclusion, in young men, aortic unloading mechanics may play a role in determining the vascular sympathetic baroreflex OP. In contrast, in middle-aged men, barosensory vessel unloading mechanics do not appear to determine the vascular sympathetic baroreflex OP and, therefore, do not contribute to age-related arterial baroreflex resetting and increased resting MSNA. NEW & NOTEWORTHY We assessed the influence of barosensory vessel mechanics (magnitude and rate of unloading and time spent unloaded) as a surrogate for baroreceptor unloading. In young men, aortic unloading mechanics are important in regulating the operating point of the vascular sympathetic baroreflex, whereas in middle-aged men, these arterial mechanics do not influence this operating point. The age-related increase in resting muscle sympathetic nerve activity does not appear to be driven by altered baroreceptor input from stiffer barosensory vessels.

Objective: To examine potential relationships between ECG characteristics and echocardiographic measures of cardiac structure in chimpanzees ( Pan troglodytes )., Animals: 341 chimpanzees (175 males and 166 females) from 5 sanctuaries and 2 zoological collections., Procedures: Chimpanzees were anesthetized for routine health examinations between May 2011 and July 2017 as part of the International Primate Heart Project and, during the same anesthetic events, underwent 12-lead ECG and transthoracic echocardiographic assessments. Relationships between results for ECG and those for echocardiographic measures of atrial areas, left ventricular internal diameter in diastole (LVIDd), and mean left ventricular wall thicknesses (MLVWT) were assessed with correlational analysis, then multiple linear regression analyses were used to create hierarchical models to predict cardiac structure from ECG findings., Results: Findings indicated correlations ( r = -0.231 to 0.310) between results for ECG variables and echocardiographic measures. The duration and amplitude of P waves in lead II had the strongest correlations with atrial areas. The Sokolow-Lyon criteria, QRS-complex duration, and R-wave amplitude in leads V 6 and II had the strongest correlations with MLVWT, whereas the Sokolow-Lyon criteria, QRS-complex duration, and S-wave amplitude in leads V 2 and V 1 had the strongest correlations with LVIDd. However, the ECG predictive models that were generated only accounted for 17%, 7%, 11%, and 8% of the variance in the right atrial end-systolic area, left atrial end-systolic area, MLVWT, and LVIDd, respectively., Conclusions and Clinical Relevance: Results indicated that relationships existed between ECG findings and cardiac morphology in the chimpanzees of the present study; however, further research is required to examine whether the predictive models generated can be modified to improve their clinical utility.

Background : Clinical electrocardiographic (ECG) guidelines for athlete's heart are based upon cross-sectional data. We aimed to longitudinally evaluate the influence of endurance training on the ECG and compare the prevalence of ECG abnormalities defined by contemporary criteria. Methods : A group of 66 training-naïve individuals completed a six-month training programme with resting ECGs and cardiopulmonary exercise tests performed at baseline, two and six months. Data were analysed using repeated measures analysis of variance and the prevalence of ECG abnormalities compared between proposed criteria. Results : Maximal oxygen consumption increased from 45.4 ± 7.1 to 50.3 ± 7.1 ml·kg -1 ·min -1 ( p <  0.05) pre-to-post training. ECG changes included, bradycardia (60 ± 12 vs. 53 ± 8 beats·min -1 ; p <  0.05), shorter P wave duration (106 ± 10 vs. 103 ± 11 ms; p <  0.05), reduced QTc (413 ± 27 vs. 405 ± 22 ms; p <  0.05), and increased left ventricular Sokolow-Lyon index (2.45 ± 0.66 vs. 2.62 ± 0.78 mV; p <  0.05). 85% of individuals showed ≥1 'training-related' ECG finding at six months vs. 68% at baseline. Using the 2013 Seattle Criteria, 4 ECGs were 'abnormal' at baseline and 3 at month six vs. 2 at baseline and 1 at month six, using the 2017 International Consensus. Prevalence of 'borderline' findings did not increase with training (11% at baseline and six months). Conclusion : Six-months endurance training leads to a greater prevalence of 'training-related' but not 'borderline' or 'training-unrelated' ECGs. 'Borderline findings' may not necessarily represent training-related cardiac remodelling in novice athletes following a six-month training intervention. KEY MESSAGES This study aimed to assess the longitudinal ECG changes following six months of endurance training, in training-naïve individuals, and whether these ECG changes support the revisions made to the recent 2017 international consensus criteria. The prevalence of 'training-related' findings were increased with six months of endurance training, however the prevalence of the revised 'borderline' criteria, according to the 2017 international consensus, did not increase and the associated quantitative ECG data (e.g. P-wave amplitude, QRS axis and QRS duration) remained unchanged. Further clinical consideration may be warranted for individuals within the early phase of exercise engagement presenting with 'borderline' ECG abnormalities, defined by the International criteria.

Chimpanzees and gorillas, when not inactive, engage primarily in short bursts of resistance physical activity (RPA), such as climbing and fighting, that creates pressure stress on the cardiovascular system. In contrast, to initially hunt and gather and later to farm, it is thought that preindustrial human survival was dependent on lifelong moderate-intensity endurance physical activity (EPA), which creates a cardiovascular volume stress. Although derived musculoskeletal and thermoregulatory adaptations for EPA in humans have been documented, it is unknown if selection acted similarly on the heart. To test this hypothesis, we compared left ventricular (LV) structure and function across semiwild sanctuary chimpanzees, gorillas, and a sample of humans exposed to markedly different physical activity patterns. We show the human LV possesses derived features that help augment cardiac output (CO) thereby enabling EPA. However, the human LV also demonstrates phenotypic plasticity and, hence, variability, across a wide range of habitual physical activity. We show that the human LV's propensity to remodel differentially in response to chronic pressure or volume stimuli associated with intense RPA and EPA as well as physical inactivity represents an evolutionary trade-off with potential implications for contemporary cardiovascular health. Specifically, the human LV trades off pressure adaptations for volume capabilities and converges on a chimpanzee-like phenotype in response to physical inactivity or sustained pressure loading. Consequently, the derived LV and lifelong low blood pressure (BP) appear to be partly sustained by regular moderate-intensity EPA whose decline in postindustrial societies likely contributes to the modern epidemic of hypertensive heart disease., Competing Interests: The authors declare no conflict of interest., (Copyright © 2019 the Author(s). Published by PNAS.)

Objective: To evaluate left ventricular (LV) mechanics in the second trimester of healthy pregnancy and to determine the influence of underpinning hemodynamics (heart rate (HR), preload and afterload) on LV mechanics during gestation., Methods: This was a cross-sectional study of 18 non-pregnant, 14 nulliparous pregnant (22-26 weeks' gestation) and 13 primiparous postpartum (12-16 weeks after delivery) women. All pregnant and postpartum women had uncomplicated, singleton gestations. Cardiac structure and function were assessed using echocardiography. LV mechanics, specifically longitudinal strain, circumferential strain and twist/untwist, were measured using speckle-tracking echocardiography. Differences between groups were identified using ANCOVA, with age, HR, end-diastolic volume (EDV) and systolic blood pressure (SBP) as covariates. Relationships between LV mechanics and hemodynamics were examined using Pearson's correlation., Results: There were no significant differences in LV structure and traditional measurements of systolic and diastolic function between the three groups. Pregnant women, compared with non-pregnant ones, had significantly higher resting longitudinal strain (-22 ± 2% vs -17 ± 3%; P = 0.002) and basal circumferential strain (-23 ± 4% vs -16 ± 2%; P = 0.001). Apical circumferential strain and LV twist and untwist mechanics were similar between the three groups. No statistically significant relationships were observed between LV mechanics and HR, EDV or SBP within the groups., Conclusions: Compared to the non-pregnant state, pregnant women in the second trimester of a healthy pregnancy have significantly greater resting systolic function, as assessed by LV longitudinal and circumferential strain. Contrary to previous work, these data show that healthy pregnant women should not exhibit reductions in resting systolic function between 22 and 26 weeks' gestation. The enhanced myocardial contractile function during gestation does not appear to be related to hemodynamic load and could be the result of other physiological adaptations to pregnancy. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd., (Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.)

This study focused on the influence of habitual endurance exercise training (i.e., committed runner or nonrunner) on the regulation of muscle sympathetic nerve activity (MSNA) and arterial pressure in middle-aged (50 to 63 yr, n = 23) and younger (19 to 30 yr; n = 23) normotensive men. Hemodynamic and neurophysiological assessments were performed at rest. Indices of vascular sympathetic baroreflex function were determined from the relationship between spontaneous changes in diastolic blood pressure (DBP) and MSNA. Large vessel arterial stiffness and left ventricular stroke volume also were measured. Paired comparisons were performed within each age category. Mean arterial pressure and basal MSNA bursts/min were not different between age-matched runners and nonrunners. However, MSNA bursts/100 heartbeats, an index of baroreflex regulation of MSNA (vascular sympathetic baroreflex operating point), was higher for middle-aged runners ( P = 0.006), whereas this was not different between young runners and nonrunners. The slope of the DBP-MSNA relationship (vascular sympathetic baroreflex gain) was not different between groups in either age category. Aortic pulse wave velocity was lower for runners of both age categories ( P < 0.03), although carotid β-stiffness was lower only for middle-aged runners ( P = 0.04). For runners of both age categories, stroke volume was larger, whereas heart rate was lower (both P < 0.01). In conclusion, we suggest that neural remodeling and upward setting of the vascular sympathetic baroreflex compensates for cardiovascular adaptations after many years committed to endurance exercise training, presumably to maintain arterial blood pressure stability. NEW & NOTEWORTHY Exercise training reduces muscle sympathetic burst activity in disease; this is often extrapolated to infer a similar effect in health. We demonstrate that burst frequency of middle-aged and younger men committed to endurance training is not different compared with age-matched casual exercisers. Notably, well-trained, middle-aged runners display similar arterial pressure but higher sympathetic burst occurrence than untrained peers. We suggest that homeostatic plasticity and upward setting of the vascular sympathetic baroreflex maintains arterial pressure stability following years of training.

Objective: To comprehensively characterize cardiac structure and function, from infancy to adulthood, in male and female wild-born captive chimpanzees ( Pan troglodytes ) living in sanctuaries., Animals: 290 wild-born captive chimpanzees., Procedures: Physical and echocardiographic examinations were performed on anesthetized chimpanzees in 3 sanctuaries in Africa between October 2013 and May 2017. Results were evaluated across age groups and between sexes, and potential differences were assessed with multiple 1-way independent Kruskal-Wallis tests., Results: Results indicated that left ventricular diastolic and systolic function declined at a younger age in males than in females. Although differences in right ventricular diastolic function were not identified among age groups, right ventricular systolic function was lower in adult chimpanzees (> 12 years old), compared with subadult (8 to 12 years old) and juvenile (5 to 7 years old) chimpanzees. In addition, male subadult and adult chimpanzees had larger cardiac wall dimensions and chamber volumes than did their female counterparts., Conclusions and Clinical Relevance: Results of the present study provided useful reference intervals for cardiac structure and function in captive chimpanzees categorized on the basis of age and sex; however, further research is warranted to examine isolated and combined impacts of blood pressure, age, body weight, and anesthetic agents on cardiac structure and function in chimpanzees.

Left ventricular (LV) twist mechanics differ between men and women during acute physiological stress, which may be partly mediated by sex differences in autonomic control. While men appear to have greater adrenergic control of LV twist, the potential contribution of vagal modulation to sex differences in LV twist remains unknown. Therefore, the present study examined the role of vagal control on sex differences in LV twist during graded lower body negative pressure (LBNP) and supine cycling. On two separate visits, LV mechanics were assessed using two-dimensional speckle-tracking echocardiography in 18 men (22 ± 2 yr) and 17 women (21 ± 4 yr) during -40- and -60-mmHg LBNP and 25% and 50% of peak supine cycling workload with and without glycopyrrolate (vagal blockade). LV twist was not different at baseline but was greater in women during -60 mmHg in both control (women: 16.0 ± 3.4° and men: 12.9 ± 2.3°, P = 0.004) and glycopyrrolate trials (women: 17.7 ± 5.9° and men: 13.9 ± 3.3°, P < 0.001) due to greater apical rotation during control (women: 11.9 ± 3.6° and men: 7.8 ± 1.5°, P < 0.001) and glycopyrrolate (women: 11.6 ± 4.9° and men: 7.1 ± 3.6°, P = 0.009). These sex differences in LV twist consistently coincided with a greater LV sphericity index (i.e., ellipsoid geometry) in women compared with men. In contrast, LV twist did not differ between the sexes during exercise with or without glycopyrrolate. In conclusion, women have augmented LV twist compared with men during large reductions to preload, even during vagal blockade. As such, differences in vagal control do not appear to contribute to sex differences in the LV twist responses to physiological stress, but they may be related to differences in ventricular geometry. NEW & NOTEWORTHY This is the first study to specifically examine the role of vagal autonomic control on sex-related differences in left ventricular (LV) mechanics. Contrary to our hypothesis, vagal control does not appear to primarily determine sex differences in LV mechanical or hemodynamic responses to acute physiological stress. Instead, differences in LV geometry may be a more important contributor to sex differences in LV mechanics.

Exercise-induced cardiac remodeling (EICR) and the attendant myocardial adaptations characteristic of the athlete's heart may regress during periods of exercise reduction or abstinence. The time course and mechanisms underlying this reverse remodeling, specifically the impact of concomitant plasma volume (PV) contraction on cardiac chamber size, remain incompletely understood. We therefore studied recreational runners ( n = 21, age 34 ± 7 yr; 48% male) who completed an 18-wk training program (~7 h/wk) culminating in the 2016 Boston Marathon after which total exercise exposure was confined to <2 h/wk (no single session >1 h) for 8 wk. Cardiac structure and function, exercise capacity, and PV were assessed at peak fitness (10-14 days before) and at 4 wk and 8 wk postmarathon. Mixed linear modeling adjusting for age, sex, V̇o 2peak , and marathon finish time was used to compare data across time points. Physiological detraining was evidenced by serial reductions in treadmill performance. Two distinct phases of myocardial remodeling and hematological adaptation were observed. After 4 wk of detraining, there were significant reductions in PV (Δ -6.0%, P < 0.01), left ventricular (LV) wall thickness (Δ -8.1%, <0.05), LV mass (Δ -10.3%, P < 0.001), and right atrial area (Δ -8.2%, P < 0.001). After 8 wk of detraining, there was a significant reduction in right ventricle chamber size (end-diastolic area Δ = -8.0%, P < 0.05) without further concomitant reductions in PV or LV wall thickness. Abrupt reductions in exercise training stimulus result in a structure-specific time course of reverse cardiac remodeling that occurs largely independently of PV contraction. NEW & NOTEWORTHY Significant reverse cardiac remodeling, previously documented among competitive athletes, extends to recreational runners and occurs with a distinct time course. Initial reductions in plasma volume and left ventricular (LV) mass, driven by reductions in wall thickness, are followed by contraction of the right ventricle. Consistent with data from competitive athletes, LV chamber volumes appear less responsive to detraining and may be a more permanent adaptation to sport.

Purpose: In rodents, a single exercise bout performed 24 h prior to a single doxorubicin treatment provides cardio-protection. This study investigated whether performing this intervention prior to every doxorubicin treatment for breast cancer reduced subclinical cardiotoxicity and treatment symptoms., Methods: Twenty-four women with early stage breast cancer were randomly assigned to perform a 30-min, vigorous-intensity treadmill bout 24 h prior to each of four doxorubicin-containing chemotherapy treatments or to usual care. Established echocardiographic and circulating biomarkers of subclinical cardiotoxicity, as well as blood pressure and body weight were measured before the first and 7-14 days after the last treatment. The Rotterdam symptom checklist was used to assess patient-reported symptoms., Results: The exercise and usual care groups did not differ in the doxorubicin-related change in longitudinal strain, twist, or cardiac troponin. However, the four total exercise bouts prevented changes in hemodynamics (increased cardiac output, resting heart rate, decreased systemic vascular resistance, p < 0.01) and reduced body weight gain, prevalence of depressed mood, sore muscles, and low back pain after the last treatment (p < 0.05) relative to the usual care group. No adverse events occurred., Conclusions: An exercise bout performed 24 h prior to every doxorubicin treatment did not have an effect on markers of subclinical cardiotoxicity, but had a positive systemic effect on hemodynamics, musculoskeletal symptoms, mood, and body weight in women with breast cancer. A single exercise bout prior to chemotherapy treatments may be a simple clinical modality to reduce symptoms and weight gain among women with breast cancer.

Background: Preclinical studies have reported that a single treadmill session performed 24h prior to doxorubicin provides cardio-protection. We aimed to characterize the acute change in cardiac function following an initial doxorubicin treatment in humans and determine whether an exercise session performed 24h prior to treatment changes this response., Methods: Breast cancer patients were randomized to either 30min of vigorous-intensity exercise 24h prior to the first doxorubicin treatment (n=13), or no vigorous exercise for 72h prior to treatment (control, n=11). Echocardiographically-derived left ventricular volumes, longitudinal strain, twist, E/A ratio, and circulating NT-proBNP, a marker of later cardiotoxicity, were measured before and 24-48h after the treatment., Results: Following treatment in the control group, NT-proBNP, end-diastolic and stroke volumes, cardiac output, E/A ratio, strain, diastolic strain rate, twist, and untwist velocity significantly increased (all p≤0.01). Whereas systemic vascular resistance (p<0.01) decreased, and ejection fraction (p=0.02) and systolic strain rate (p<0.01) increased in the exercise group only. Relative to control, the exercise group had a significantly lower NT-proBNP (p<0.01) and a 46% risk reduction of exceeding the cut-point used to exclude acute heart failure., Conclusion: The first doxorubicin treatment is associated with acutely increased NT-proBNP, echocardiographic parameters of myocardial relaxation, left ventricular volume overload, and changes in longitudinal strain and twist opposite in direction to documented longer-term changes. An exercise session performed 24h prior to treatment attenuated NT-proBNP release and increased systolic function. Future investigations should verify these findings in a larger cohort and across multiple courses of doxorubicin., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objectives: Cardiovascular function generally decreases with age, but whether this decrease differs between men and women is unclear. Our aims were twofold: (1) to investigate age-related sex differences in left ventricular (LV) structure, function and mechanics, and (2) to compare these measures between pre- and postmenopausal women in the middle-aged group., Methods: Resting echocardiography was performed in a cross-sectional sample of 82 healthy adults (14 young men, 19 middle-aged men, 15 young women, 34 middle-aged women: 15 premenopausal and 19 postmenopausal). Two-way ANOVAs were used to examine sex × age interactions, and t-tests to compare pre- and postmenopausal women (α < 0.1)., Results: Normalized LV mass, stroke volume and end-diastolic volume were significantly lower in middle-aged than young men, but this difference was smaller between middle-aged and young women. Peak systolic apical mechanics were significantly greater in middle-aged men than in middle-aged women, but not between young men and women. Postmenopausal women had significantly lower LV relaxation and mechanics (torsion, twisting velocity and apical circumferential strain rates) compared with middle-aged premenopausal women., Conclusion: Our cross-sectional findings suggest that the hearts of men and women may age differently, with men displaying greater differences in LV volumes accompanied by differences in apical mechanics.

Limited data are available on hemodynamic responses to anesthetic protocols in wild-born chimpanzees (Pan troglodytes). Accordingly, this study characterized the heart rate (HR) and blood pressure responses to four anesthetic protocols in 176 clinically healthy, wild-born chimpanzees undergoing routine health assessments. Animals were anesthetized with medetomidine-ketamine (MK) (n = 101), tiletamine-zolazepam (TZ) (n = 30), tiletamine-zolazepam-medetomidine (TZM) (n = 24), or medetomidine-ketamine (maintained with isoflurane) (MKI) (n = 21). During each procedure, HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were regularly recorded. Data were grouped according to anesthetic protocol, and mean HR, SBP, and DBP were calculated. Differences between mean HR, SBP, and DBP for each anesthetic protocol were assessed using the Kruskall-Wallis test and a Dunn multiple comparisons post hoc analysis. To assess the hemodynamic time course response to each anesthetic protocol, group mean data (±95% confidence interval [CI]) were plotted against time postanesthetic induction. Mean HR (beats/min [CI]) was significantly higher in TZ (86 [80-92]) compared to MKI (69 [61-78]) and MK (62 [60-64]) and in TZM (73 [68-78]) compared to MK. The average SBP and DBP values (mm Hg [CI]) were significantly higher in MK (130 [126-134] and 94 [91-97]) compared to TZ (104 [96-112] and 58 [53-93]) and MKI (113 [103-123] and 78 [69-87]) and in TZM (128 [120-135] and 88 [83-93]) compared to TZ. Time course data were markedly different between protocols, with MKI showing the greatest decline over time. Both the anesthetic protocol adopted and the timing of measurement after injection influence hemodynamic recordings in wild-born chimpanzees and need to be considered when monitoring or assessing cardiovascular health.

Key Points: Sex differences in left ventricular (LV) mechanics occur during acute physiological challenges; however, it is unknown whether sex differences in LV mechanics are fundamentally regulated by differences in adrenergic control. Using two-dimensional echocardiography and speckle tracking analysis, this study compared LV mechanics in males and females matched for LV length during post-exercise ischaemia (PEI) and β 1 -adrenergic receptor blockade. Our data demonstrate that while basal rotation was increased in males, LV twist was not significantly different between the sexes during PEI. In contrast, during β 1 -adrenergic receptor blockade, LV apical rotation, twist and untwisting velocity were reduced in males compared to females. Significant relationships were observed between LV twist and LV internal diameter and sphericity index in females, but not males. These findings suggest that LV twist mechanics may be more sensitive to alterations in adrenergic stimulation in males, but more highly influenced by ventricular structure and geometry in females., Abstract: Sex differences in left ventricular (LV) mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV haemodynamics. Accordingly, this study aimed to investigate sex differences in LV mechanics with altered adrenergic stimulation achieved through post-handgrip-exercise ischaemia (PEI) and β 1 -adrenergic receptor (AR) blockade. Twenty males (23 ± 5 years) and 20 females (22 ± 3 years) were specifically matched for LV length (males: 8.5 ± 0.5 cm, females: 8.2 ± 0.6 cm, P = 0.163), and two-dimensional speckle-tracking echocardiography was used to assess LV structure and function at baseline, during PEI and following administration of 5 mg bisoprolol (β 1 -AR antagonist). During PEI, LV end-diastolic volume and stroke volume were increased in both groups (P < 0.001), as was end-systolic wall stress (P < 0.001). LV twist and apical rotation were not altered from baseline or different between the sexes; however, basal rotation increased in males (P = 0.035). During β 1 -AR blockade, LV volumes were unchanged but blood pressure and heart rate were reduced in both groups (P < 0.001). LV apical rotation (P = 0.036) and twist (P = 0.029) were reduced in males with β 1 -AR blockade but not females, resulting in lower apical rotation (males: 6.8 ± 2.1 deg, females: 8.8 ± 2.3 deg, P = 0.007) and twist (males: 8.6 ± 1.9 deg, females: 10.7 ± 2.8 deg, P = 0.008), and slower untwisting velocity (males: 68.2 ± 22.1 deg s -1 , females: 82.0 ± 18.7 deg s -1 , P = 0.046) compared to females. LV twist mechanics are reduced in males compared to females during reductions to adrenergic stimulation, providing preliminary evidence that LV twist mechanics may be more sensitive to adrenergic control in males than in females., (© 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.)

Study Design: Two studies were conducted: Study-1 was cross-sectional; and Study-2 a longitudinal repeated measures design., Objectives: To examine the influence of functional electrical stimulation (FES) rowing training on cardiac structure and function in people with spinal cord injury (SCI)., Setting: A university sports science department and home-based FES-training., Methods: Fourteen participants with C4-T10 SCI (American Spinal Injury Association Impairment Scale A or B) were recruited for the studies. Cardiac structure and function, and peak: oxygen uptake ([Vdot ]O 2peak ), power output (PO peak ) and heart rate (HR peak ), were compared between two FES-untrained groups (male n=3, female n=3) and an FES-trained group (male n=3) in Study-1 and longitudinally assessed in an FES-naive group (male n=1, female n=4) in Study-2. Main outcome measures left ventricular-dimensions, volumes, mass, diastolic and systolic function, and [Vdot ]O 2peak , PO peak and HR peak . In Study-2, in addition to peak values, the [Vdot ]O 2 sustainable over 30 min and the related PO and HR were also assessed., Results: Sedentary participants with chronic SCI had cardiac structure and function at the lower limits of non-SCI normal ranges. Individuals with chronic SCI who habitually FES-row have cardiac structure and function that more closely resemble non-SCI populations. A programme of FES-rowing training improved cardiac structure and function in previously FES-naive people., Conclusion: FES-rowing training appears to be an effective stimulus for positive cardiac remodelling in people with SCI. Further work, with greater participant numbers, should investigate the impact of FES-rowing training on cardiac health in SCI., Sponsorship: We thank the INSPIRE Foundation, UK, for funding these studies.

The anatomy of the adult human left ventricle (LV) is the result of its complex interaction with its environment. From the fetal to the neonatal to the adult form, the human LV undergoes an anatomical transformation that finally results in the most complex of the four cardiac chambers. In its adult form, the human LV consists of two muscular helixes that surround the midventricular circumferential layer of muscle fibers. Contraction of these endocardial and epicardial helixes results in a twisting motion that is thought to minimize the transmural stress of the LV muscle. In the healthy myocardium, the LV twist response to stimuli that alter preload, afterload, or contractility has been described and is deemed relatively consistent and predictable. Conversely, the LV twist response in patient populations appears to be a little more variable and less predictable, yet it has revealed important insight into the effect of cardiovascular disease on LV mechanical function. This review discusses important methodological aspects of assessing LV twist and evaluates the LV twist responses to the main physiological and pathophysiological states. It is concluded that correct assessment of LV twist mechanics holds significant potential to advance our understanding of LV function in human health and cardiovascular disease., (Copyright © 2016 the American Physiological Society.)

Compared to males, females have smaller left ventricular (LV) dimensions and volumes, higher ejection fractions (EF), and higher LV longitudinal and circumferential strain. LV twist mechanics determine ventricular function and are preload-dependent. Therefore, the sex differences in LV structure and myocardial function may result in different mechanics when preload is altered. This study investigated sex differences in LV mechanics during acute challenges to preload. With the use of conventional and speckle-tracking echocardiography, LV structure and function were assessed in 20 males (24 ± 6.2 yr) and 20 females (23 ± 3.1 yr) at baseline and during progressive levels of lower body negative pressure (LBNP). Fourteen participants (8 males, 6 females) were also assessed following a rapid infusion of saline. LV end-diastolic volume, end-systolic volume, stroke volume (SV), and EF were reduced in both groups during LBNP (P < 0.001). While males had greater absolute volumes (P < 0.001), there were no sex differences in allometrically scaled volumes at any stage. Sex differences were not detected at baseline in basal rotation, apical rotation, or twist. Apical rotation and twist increased in both groups (P < 0.001) with LBNP. At -60 mmHg, females had greater apical rotation (P = 0.009), twist (P = 0.008), and torsion (P = 0.002) and faster untwisting velocity (P = 0.02) than males. There were no differences in mechanics following saline infusion. Females have larger LV twist and a faster untwisting velocity than males during large reductions to preload, supporting that females have a greater reliance on LV twist mechanics to maintain SV during severe reductions to preload., (Copyright © 2016 the American Physiological Society.)

Objective: To generate reference intervals for ECG variables in clinically normal chimpanzees (Pan troglodytes)., Animals: 100 clinically normal (51 young [< 10 years old] and 49 adult [≥ 10 years old]) wild-born chimpanzees., Procedures: Electrocardiograms collected between 2009 and 2013 at the Tchimpounga Chimpanzee Rehabilitation Centre were assessed to determine heart rate, PR interval, QRS duration, QT interval, QRS axis, P axis, and T axis. Electrocardiographic characteristics for left ventricular hypertrophy (LVH) and morphology of the ST segment, T wave, and QRS complex were identified. Reference intervals for young and old animals were calculated as mean ± 1.96•SD for normally distributed data and as 5th to 95th percentiles for data not normally distributed. Differences between age groups were assessed by use of unpaired Student t tests. RESULTS Reference intervals were generated for young and adult wild-born chimpanzees. Most animals had sinus rhythm with small or normal P wave morphology; 24 of 51 (47%) young chimpanzees and 30 of 49 (61%) adult chimpanzees had evidence of LVH as determined on the basis of criteria for humans., Conclusions and Clinical Relevance: Cardiac disease has been implicated as the major cause of death in captive chimpanzees. Species-specific ECG reference intervals for chimpanzees may aid in the diagnosis and treatment of animals with, or at risk of developing, heart disease. Chimpanzees with ECG characteristics outside of these intervals should be considered for follow-up assessment and regular cardiac monitoring.

Study Design: A training intervention study using functional electrical stimulation-rowing (FES-R) in a group of eight individuals with tetraplegia., Objectives: To assess the feasibility of a structured progressive FES-R training programme in people with tetraplegia, and to explore the number and type of FES-training sessions required to enable continuous FES-R for 30 min., Setting: A fully integrated sports centre, elite rowing training centre and university sport science department., Methods: Eight participants with chronic complete and incomplete tetraplegia (C4 to C7, American Spinal Injury Association Impairment Scale A, B and C) who had not previously used any form of FES-assisted exercise, participated in the study. Participants completed a progressive FES-assisted training programme building to three continuous 30-min FES-R sessions per week at 60-80% of their predetermined peak power output. Thereafter, rowing performance was monitored for 12 months., Main Outcome Measures: number and type of FES-training sessions required before achieving 30-min continuous FES-R, and FES-R average power output (POav) pre and post 12 months training. Participant feedback of perceived benefits was also documented., Results: All participants were able to continuously FES-row for 30 min after completing 13±7 FES-R training sessions. Each individual POav during 30 min FES-R increased over 12 months FES-training. FES-R was found safe and well tolerated in this group of individuals with tetraplegia., Conclusion: Individuals with tetraplegia are able to engage in a progressive programme of FES-R training. Future research examining FES-R training as an adjunctive therapy in people with tetraplegia is warranted.

The impact of endurance exercise training on the heart has received significant research and clinical attention for well over a century. Despite this, many issues remain controversial and clinical interpretation can be complex of biomarkers of cardiomyocyte insult. This review assesses the current state of knowledge related to two areas of research where problems with clinical decision making may arise: (1) the impact of chronic endurance exercise training on cardiac structure, function and electrical activity to the point where the athletic heart phenotype may be similar to the expression of some cardiac pathologies (a diagnostic dilemma referred to as the 'grey-zone') and (2) the impact of acute bouts of prolonged exercise on cardiac function and the presentation of biomarkers and cardiomyocyte insult in the circulatory system. The combination of acute endurance exercise stress on the heart and prolonged periods of training are considered together in the final section.

We asked whether abdominal binding improves cardiorespiratory function in individuals with cervical spinal cord injury (SCI). 13 participants with chronic SCI (C(5)-C(7)) and 8 able-bodied controls were exposed to varying degrees of elastic abdominal compression (unbound [UB], loose-bound [LB], and tight-bound [TB]) while seated. In SCI, TB increased vital capacity (14%), expiratory flow throughout vital capacity (15%), inspiratory capacity (21%), and maximal expiratory mouth pressure (25%). In contrast, TB reduced residual volume (-34%) and functional residual capacity (-23%). TB increased tidal and twitch transdiaphragmatic pressures (∼45%), primarily by increasing the gastric pressure contributions. TB increased cardiac output (28%), systolic mitral annular velocity (22%), and late-diastolic mitral annular velocity (50%). Selected measures of cardiorespiratory function improved with LB, but the changes were less compared to TB. In able-bodied, changes were inconsistent and always less than in SCI. In conclusion, abdominal-binding improved cardiorespiratory function in low-cervical SCI by optimising operating lung volumes, increasing expiratory flow, enhancing diaphragmatic pressure production, and improving left-ventricular function., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Purpose: The purposes of this study were to describe resting cardiopulmonary function in highly trained athletes with cervical spinal cord injury (SCI) and to compare the data with able-bodied (AB) control subjects., Methods: Twelve Paralympic wheelchair rugby players with cervical SCI (injury level = C5-C7) and 12 AB controls matched for age, stature, and body mass were assessed for pulmonary function using spirometry, body plethysmography, and maximal inspiratory and expiratory mouth pressures; diaphragm function using magnetic stimulation of the phrenic nerves; and cardiac function using transthoracic echocardiography., Results: Total lung capacity, vital capacity, inspiratory reserve volume, and expiratory reserve volume were lower in SCI compared with AB (P < 0.01), whereas residual volume was elevated in SCI (P = 0.022). Airway resistance and maximal inspiratory mouth pressure were not different between groups (P > 0.41), whereas maximal expiratory mouth pressure, maximal transdiaphragmatic pressure, and twitch transdiaphragmatic pressure were lower in SCI (P < 0.01). Percent predicted total lung capacity was significantly correlated with maximal transdiaphragmatic pressure in SCI (r = 0.74), suggesting that the pulmonary restriction was a result of diaphragm weakness. Left ventricular mass, ejection fraction, stroke volume, and cardiac output were lower in SCI (P < 0.04), but early and late filling velocities during diastole were not different between groups (P > 0.05)., Conclusions: Highly trained athletes with cervical SCI exhibit a restrictive pulmonary defect, weakness of the expiratory and diaphragm muscles, atrophy of the heart, and reduced systolic cardiac function.

Left ventricular (LV) diastolic function is important because the enhanced systolic function that underpins high levels of cardio-respiratory fitness has to be matched by changes in LV filling, and LV diastolic dysfunction plays a key early role in the development and progression of a myriad of cardiovascular diseases. This review serves to detail knowledge in relation to: (1) the definition of diastole and the mechanical processes that occur during the diastolic period, (2) the quantitative assessment of diastolic function, predominantly focusing on non-invasive echocardiographic imaging modes such as tissue Doppler imaging and deformation analysis, (3) the impact of acute aerobic exercise on diastolic function, from the augmentation of function necessary to meet the demand for an increased cardiac output at exercise onset, to current concerns related to the impact of prolonged or ultra-endurance activity on diastolic function during recovery, (4) the adaptation in diastolic function observed with chronic aerobic exercise training in athletes and sedentary individuals who undergo training programmes, and (5) directions for future research.

Prolonged exercise has been shown to result in an acute depression in cardiac function. However, little is known about the effect of this type of exercise on vascular function. Therefore, the purpose of the present study was to investigate the impact of an acute bout of prolonged strenuous exercise on vascular and cardiac function and the appearance of biomarkers of cardiomyocyte damage in 15 male (32 +/- 10 yr) nonelite runners. The subjects were tested on two occasions, the day before and within an hour of finishing the London marathon (229 +/- 38 min). Function of the brachial and femoral arteries was determined using flow-mediated dilatation (FMD). Echocardiographic assessment of cardiac strain, strain rate, tissue velocities, and flow velocities during diastole and systole were also obtained. Venous blood samples were taken for later assessment of cardiac troponin I (cTnI), a biomarker of cardiomyocyte damage. Completion of the marathon resulted in a depression in femoral (P = 0.04), but not brachial (P = 0.96), artery FMD. There was no change, pre- vs. postmarathon, in vascular shear, indicating that the impaired femoral artery function was not related to hemodynamic changes. The ratio of peak early to atrial radial strain rate, a measure of left ventricular diastolic function, was reduced postmarathon (P = 0.006). Postrace cTnI was elevated in 12 of 13 runners, with levels above the recognized clinical threshold for damage in 7 of these. In conclusion, when taken together, these data suggest a transient depression in cardiac and leg vascular function following prolonged intensive exercise.

Background: Prolonged steady state exercise can lead to a decrease in left ventricular (LV) function as well as promote the release of cardiac troponin T (cTnT). There is limited information on the effect of intermittent high intensity exercise of moderate duration., Objectives: To determine the effect of intermittent high intensity exercise of moderate duration on LV function., Methods: Nineteen male rugby and football players (mean (SD) age 21 (2) years) volunteered. Assessments, before, immediately after, and 24 hours after competitive games, included body mass, heart rate (HR), and systolic blood pressure (sBP) as well as echocardiography to assess stroke volume (SV), ejection fraction (EF), systolic blood pressure/end systolic volume ratio (sBP/ESV), and global diastolic filling (E:A) as well as to indirectly quantify preload (LV internal dimension at end diastole (LVIDd)). Serum cTnT was analysed using a 3rd generation assay. Changes in LV function were analysed by repeated measures analysis of variance. cTnT data are presented descriptively., Results: SV (91 (26) v 91 (36) v 90 (35) ml before, after, and 24 hours after the game respectively), EF (71 (8) v 70 (9) v 71 (7)%), and sBP/ESV (4.2 (1.8) v 3.8 (1.9) v 4.1 (1.6) mm Hg/ml) were not significantly altered (p>0.05). Interestingly, whereas LVIDd was maintained after the game (50 (5) v 50 (6) mm), sBP was transiently but significantly reduced (131 (3) v 122 (3) mm Hg; p<0.05). E:A was moderately (p<0.05) reduced after the game (2.0 (0.4) v 1.5 (0.4)) but returned to baseline within 24 hours. No blood sample contained detectable levels of cTnT., Conclusions: In this cohort, LV systolic function was not significantly altered after intermittent activity. A transient depression in global diastolic filling was partially attributable to a raised HR and could not be explained by myocyte disruption as represented by cTnT release.

Background: Exercise induced cardiac fatigue has recently been observed after prolonged exercise. A moderate to high altitude has been suggested as a possible stimulus in the genesis of such cardiac fatigue., Objective: To investigate if exercise induced cardiac fatigue and or cardiac damage occurs after prolonged exercise in a hypoxic environment., Methods: Eight trained male triathletes volunteered for the study. Each completed two 50 mile cycle trials, randomly assigned from normobaric normoxia and normobaric hypoxia (15% FIO(2)). Echocardiographic assessment and whole blood collection was completed before, immediately after, and 24 hours after exercise. Left ventricular systolic and diastolic functional variables were calculated, and serum was analysed for cardiac troponin T. Results were analysed using a two way repeated measures analysis of variance, with alpha set at 0.05., Results: No significant differences were observed in either systolic or diastolic function across time or between trials. Cardiac troponin T was detected in one subject immediately after exercise in the normobaric hypoxic trial., Conclusions: A 50 mile cycle trial in either normobaric normoxia or normobaric hypoxia does not induce exercise induced cardiac fatigue. Some people, however, may exhibit minimal cardiac damage after exercise in normobaric hypoxia. The clinical significance of this is yet to be elucidated.

Cardiac damage has recently been implicated in the aetiology of "exercise induced cardiac dysfunction". The humoral markers of cardiac damage that have been utilised to date are not sufficiently cardio-specific to investigate this hypothesis. The aim of the present study was to examine cardiac function following prolonged exercise, and investigate the contention of cardiac damage utilising a new highly cardio-specific marker. Thirty-seven competitors in the 2-day Lowe Alpine Mountain Marathon 2000 volunteered for the study. Competitors were sub-divided into 2 groups. Group 1 (n = 11) were examined using echocardiography pre and post the event, examining left ventricular diastolic and systolic function. Group 2 (n = 26) had venous blood samples drawn prior to the event and immediately following day-1 and day-2. Blood samples were analysed for total creatine kinase activity (CK), creatine kinase isoenzyme MB(mass) (CK-MB(mass)), and cardiac troponin T. Echocardiographic results indicated left ventricular diastolic and systolic dysfunction following cessation of exercise. CK and CK-MB(mass) were both elevated following day-1, and immediately following race completion. Cardiac troponin T levels were below the 99th percentile (0.01 microg/L) in all subjects prior to the event, following day-1 cTnT was elevated above 0.01 microg/L in 13 subjects, but returned to below 0.01 microg/L following race completion on day-2. However, no individual data reached clinical cut-off levels for acute myocardial infarction (AMI) (0.1 microg/L). Two days arduous exercise over mountainous terrain resulted in cardiac dysfunction, and significant skeletal muscular degradation. The elevation of cTnT above the 99th percentile in the present study is suggestive of minimal myocardial damage. The clinical significance of and exact mechanism responsible for such damage remains to be elucidated.