The athlete's heart. A meta-analysis of cardiac structure and function

The Changes of Heart miR-1 and miR-133 Expressions following Physiological Hypertrophy Due to Endurance Training

Objective

MicroRNAs (miRNAs) play a key role in the development of the heart. Recent studies have shown that miR- 1 and miR-133 are key regulators of cardiac hypertrophy. Therefore, we aimed to evaluate the effect of an endurance training (ET) program on the expressions of these miRNAs and their transcriptional network.

Materials and Methods

In this experimental study, cardiac hypertrophy was induced by 14 weeks of ET for 1 hour per day, 6 days per week at 75% VO2 max). The rats (221 ± 23 g) in the experimental (n=7) and control (n=7) groups were anesthetized to evaluate heart morphology changes by echocardiography. Next, we evaluated expressions of miR-1 and miR-133, and heart and neural crest derivatives express 2 (Hand2), Mef2c, histone deacetylase 4 (Hdac4) and serum response factor (Srf) gene expressions by real-time polymerase chain reaction (PCR). Finally, the collected data were evaluated by the independent t test to determine differences between the groups

Results

The echocardiography result confirmed physiological hypertrophy in the experimental group that underwent ET as shown by the increased left ventricular weight/body surface area (LVW/BSA) (P=0.004), LVW/body weight (BW) (P=0.011), left ventricular diameter end-diastolic (LVDd) (P=0.003), and improvements in heart functional indexes such as fractional shortness (FS) (P=0.036) and stroke volume (SV) (P=0.002). There were significant increases in the expressions of miR-1 (P=0.001) and miR-133 (P=0.004). The expressions of Srf, Hdac4, and Hand2 genes significantly increased (P<0.001) in the experimental group Compared with the control group. The expression of Mef2c did not significantly change.

Conclusion

The expressions of miR-1 and miR-133 and their target genes appeared to be involved in physiological hypertrophy induced by ET in these rats.

High-intensity endurance training is associated with left atrial fibrosis

INTRODUCTION

Endurance athletes are at higher risk for developing atrial fibrillation as compared to the general population. The exact mechanism to explain this observation is incompletely understood. Our study aimed to determine whether degree of left atrial fibrosis detected by late gadolinium-enhancement magnetic resonance imaging (LGE-MRI) differed between Masters athletes and non-athlete controls.

METHODS

We recruited 20 endurance healthy Masters athletes and 20 healthy control subjects who underwent cardiac MRI. Healthy controls were recruited during screening colonoscopies and Masters athletes were recruited through word of mouth and at competitions. The two groups were age and gender matched. None of the participants were known to have an arrhythmia. Fibrosis, as measured by late gadolinium-enhancement, was measured in each participant by blinded readers. The degree of left atrial fibrosis was compared between the two groups. All participants were recruited from the Salt Lake City region and scanned at the University of Utah healthcare complex.

RESULTS

Left ventricular function was normal in all study participants. Left atrial volumes were significantly larger in the athletes (74.2 ml ± 14.4) as compared to the healthy control subjects (60.8 mL ± 21.4) (P = .02). Mean left atrial fibrosis score, reported as a percentage of the LA, was 15.5% ± 5.9 in the athlete cohort compared to 9.6% ± 4.9 in the controls (P = .002).

CONCLUSIONS

To our knowledge this is the first study that describes, characterizes and specifically quantifies fibrotic changes within the left atrium of highly trained endurance athletes. Increased atrial fibrosis seen in this population may be an early indicator for endurance athletes at risk of developing atrial arrhythmias.

Exercise but Not Supplemental Dietary Tryptophan Influences Heart Rate and Respiratory Rate in Sled Dogs

Tryptophan (Trp), an indispensable amino acid for dogs, is the precursor of serotonin, a neurotransmitter with a variety of effects throughout the body, including the ability to modulate cardiac and pulmonary activity. This study aimed to investigate the effects of a 12-week incremental exercise regimen and supplemental dietary Trp on heart rate (HR) and respiratory rate (RR) in client-owned sled dogs. Sixteen Siberian huskies were randomly allocated to either treatment or control diet groups. Both groups were fed a control diet (Trp to large neutral amino acid ratio of 0.047:1); however, treatment dogs received a Trp supplement to achieve a Trp to large neutral amino acid ratio of 0.075:1. Every three weeks, external telemetry equipment was used to non-invasively measure and record HR and RR at a resting, working, and post-exercise state in a controlled exercise challenge. A mixed model was used to test differences between diet, activity parameter, and week. Dietary Trp supplementation had no effect on HR or RR. Independent of diet, resting, working, post-exercise HR, and time to recover post-exercise HR decreased from week −1 to week 11 (p < 0.05). Resting HR had the greatest reduction from week −1 to week 11 (21%, p < 0.05). Working RR did not change with exercise (p > 0.10), but rRR and postRR decreased from week −1 to week 11 (p < 0.05). These data suggest that the exercise regimen the dogs were subjected to may have positively impacted the dogs’ capacity to sustain aerobic exercise, whereas Trp supplementation had no effect on HR or RR.

Impact of endurance exercise on the heart of cyclists: A systematic review and meta-analysis

OBJECTIVE

To compare heart structure and function in endurance athletes relative to participants of other sports and non-athletic controls in units relative to body size. A secondary objective was to assess the association between endurance cycling and cardiac abnormalities.

PATIENTS AND METHODS

Five electronic databases (CINAHL, Cochrane Library, Medline, Scopus, and SPORTdiscus) were searched from the earliest record to 14 December 2019 to identify studies investigating cardiovascular structure and function in cyclists. Of the 4865 unique articles identified, 70 met inclusion criteria and of these, 22 articles presented 10 cardiovascular parameters in units relative to body size for meta-analysis and five presented data relating to incidence of cardiac abnormalities. Qualitative analysis was performed on remaining data. The overall quality of evidence was assessed using GRADE. Odds ratios were calculated to compare the incidence of cardiac abnormality.

RESULTS

Heart structure was significantly larger in cyclists compared to non-athletic controls for left ventricular: mass; end-diastolic volume, interventricular septal diameter and internal diameter; posterior wall thickness, and end-systolic internal diameter. Compared to high static and high dynamic sports (e.g., kayaking and canoeing), low-to-moderate static and moderate-to-high dynamic sports (e.g., running and swimming) and moderate-to-high static and low-to-moderate dynamic sports (e.g., bodybuilding and wrestling), endurance cyclists end-diastolic left ventricular internal diameter was consistently larger (mean difference 1.2-3.2 mm/m²). Cardiac abnormalities were higher in cyclists compared to controls (odds ratio: 1.5, 95%CI 1.2-1.8), but the types of cardiac abnormalities in cyclists were not different to other athletes.

CONCLUSION

Endurance cycling is associated with a larger heart relative to body size and an increased incidence of cardiac abnormalities relative to controls.

A Vegan Athlete's Heart-Is It Different? Morphology and Function in Echocardiography

Plant-based diets are a growing trend, including among athletes. This study compares the differences in physical performance and heart morphology and function between vegan and omnivorous amateur runners. A study group and a matched control group were recruited comprising N = 30 participants each. Eight members of the study group were excluded, leaving N = 22 participants. Members of both groups were of similar age and trained with similar frequency and intensity. Vegans displayed a higher VO2max (54.08 vs. 50.10 mL/kg/min, p < 0.05), which correlated positively with carbohydrate intake (ρ = 0.52) and negatively with MUFA (monounsaturated fatty acids) intake (ρ = −0.43). The vegans presented a more eccentric form of remodelling with greater left ventricular end diastolic diameter (LVEDd, 2.93 vs. 2.81 cm/m², p = 0.04) and a lower relative wall thickness (RWT, 0.39 vs. 0.42, p = 0.04) and left ventricular mass (LVM, 190 vs. 210 g, p = 0.01). The left ventricular mass index (LVMI) was similar (108 vs. 115 g/m², p = NS). Longitudinal strain was higher in the vegan group (−20.5 vs. −19.6%, p = 0.04), suggesting better systolic function. Higher E-wave velocities (87 vs. 78 cm/s, p = 0.001) and E/e′ ratios (6.32 vs. 5.6, p = 0.03) may suggest better diastolic function in the vegan group. The results demonstrate that following a plant-based diet does not impair amateur athletes’ performance and influences both morphological and functional heart remodelling. The lower RWT and better LV systolic and diastolic function are most likely positive echocardiographic findings.

The arrhythmogenic right ventricular cardiomyopathy in comparison to the athletic heart

Intense exercise-induced right ventricular remodeling is a potential adaptation of cardiac function and structure. The features of the remodeling may overlap with those of a very early form of arrhythmogenic right ventricular cardiomyopathy (ARVC): at this early stage, it could be difficult to discriminate ARVC, from exercise-induced cardiac adaptation that may develop in normal individuals. The purpose of this paper is to discuss which exercise-induced remodeling may be a pathological or a physiological finding. A complete evaluation may be required to identify the pathological features of ARVC that would include potential risk of sudden cardiac death during sport or, to avoid the false diagnosis of ARVC. The most recent expert assessment of arrhythmogenic cardiomyopathy focuses on endurance athletes presenting with clinical features indistinguishable from ARVC.

Assessment of cardiac variables using a new electrocardiography lead system in horses

Aim:

The objective of this study was to assess a new lead system method to improve electrocardiographic measurement in horses.

Materials and Methods:

Twenty-two horses with an average age of 8.8±0.8 years were enrolled in this study. Horses were divided into two groups, consisting of a control group (n=11) and athlete group (n=11). Electrocardiography (ECG) and echocardiography were performed to provide information on the structure and function of the heart. Two lead systems, base apex and modified precordial leads, were used for the electrocardiogram to assess the cardiac electrophysiological functions.

Results:

PR interval, QT interval, and QRS-T angle presented significant differences between the control and athlete groups when the modified precordial lead system was used. However, significant variations in the mean electrical axis were found when the base apex lead system was used. The modified precordial lead system resulted in more significant differences in cardiac electrophysiological parameters than the base apex lead system. In the athlete group, echocardiography showed cardiac adaptations such as increases in the left atrial and left ventricular dimensions and stroke volume and a decrease in heart rate in response to exercise and training. The observed differences in cardiac morphology and function between groups suggested differences in health performance in the athlete group.

Conclusion:

These data provided the first evidence that the modified precordial lead system improved statistical variation in ECG recording and provided the most reliable method for health screening in horses.

Increased myocardial mass and attenuation of myocardial strain in professional male soccer players and competitive male triathletes

The purpose of this prospective study was to analyze the relationship between ventricular morphology and parameters of cardiac function in two different athletic groups and controls, using feature tracking cardiac magnetic resonance (FT-CMR). Twenty-three professional soccer players (22 ± 4 years), 19 competitive triathletes (28 ± 6 years) and 16 controls (26 ± 3 years) were included in the study. CMR was performed using a 1.5 T scanner. Cardiac chamber volumes, mass and biventricular global myocardial strain were obtained and compared. In comparison to the control subjects, athletes were characterized by a higher cardiac volume (p < 0.0001), higher cardiac mass (p < 0.001), reduced longitudinal strain of the left and right ventricle (p < 0.05 and p < 0.01 respectively) and reduced left ventricular radial strain (p < 0.05). Soccer players revealed higher amounts of left ventricular mass (87 ± 15 vs. 75 ± 13 g/m², p < 0.05) than triathletes. Moreover, they showed a greater decrease in left and right ventricular longitudinal strain (p < 0.05 and p < 0.05) as well as in radial left ventricular strain (p < 0.05) in comparison to triathletes. An increase in left ventricular mass correlated significantly with a decrease in longitudinal (r = 0.47, p < 0.001) and radial (r =  − 0.28, p < 0.05) strain. In athletes, attenuation of strain values is associated with cardiac hypertrophy and differ between soccer players and triathletes. Further studies are needed to investigate whether it is an adaptive or maladaptive change of the heart induced by intense athletic training.

Elevated resting heart rate in adolescent men and risk of heart failure and cardiomyopathy

Aims

This study aims to investigate the association of resting heart rate (RHR) measured in late adolescence with long‐term risk of cause‐specific heart failure (HF) and subtypes of cardiomyopathy (CM), with special attention to cardiorespiratory fitness.

Methods and results

We performed a nation‐wide, register‐based cohort study of all Swedish men enrolled for conscription in 1968–2005 (n = 1 008 363; mean age = 18.3 years). RHR and arterial blood pressure were measured together with anthropometrics as part of the enlistment protocol. HF and its concomitant diagnoses, as well as all CM diagnoses, were collected from the national inpatient, outpatient, and cause of death registries. Risk estimates were calculated by Cox‐proportional hazards models while adjusting for potential confounders. During follow‐up, there were 8400 cases of first hospitalization for HF and 3377 for CM. Comparing the first and fifth quintiles of the RHR distribution, the hazard ratio (HR) for HF associated with coronary heart disease, diabetes, or hypertension was 1.25 [95% confidence interval (CI) = 1.13–1.38] after adjustment for body mass index, blood pressure, and cardiorespiratory fitness. The corresponding HR was 1.43 (CI = 1.08–1.90) for HF associated with CM and 1.34 (CI = 1.16–1.54) for HF without concomitant diagnosis. There was an association between RHR and dilated CM [HR = 1.47 (CI = 1.27–1.71)] but not hypertrophic, alcohol/drug‐induced, or other cardiomyopathies.

Conclusions

Adolescent RHR is associated with future risk of HF, regardless of associated aetiological condition. The association was strongest for HF associated with CM, driven by the association with dilated CM. These findings indicate a causal pathway between elevated RHR and myocardial dysfunction that warrants further investigation.

Are Blood Pressure and Cardiovascular Stress Greater in Isometric or in Dynamic Resistance Exercise?

Medical and sports medicine associations are reluctant to endorse isometric exercise to the same extent as dynamic resistance exercise (RE). The major concern is the fear of greater increases in blood pressure (BP) that might be associated with isometric exercise. This review comprehensively presents all human studies that directly compared the magnitude of hemodynamic responses between isometric and dynamic RE. We also discuss possible mechanisms controlling BP-response and cardiovascular adjustments during both types of RE. The most prominent finding was that isometric and dynamic RE using small-muscle mass evoke equal increases in BP; however, the circulatory adjustments contributing to this response are different in dynamic and isometric RE. In contrast, studies using large-muscle mass report inconsistent results for the magnitude of BP-response between the two types of RE. Thus, when the same muscles and workloads are used, the increase in BP during isometric and dynamic RE is more comparable to what is commonly believed. However, it should be noted that only a few studies equalized the workload in two types of RE, most used small sample sizes, and all studies employed healthy participants. More studies are needed to compare the cardiovascular risks associated with isometric and dynamic RE, especially in individuals with chronic disease.

Aerobic Training Protects Cardiac Function During Advancing Age: A Meta-Analysis of Four Decades of Controlled Studies

Background

In contrast to younger athletes, there is comparatively less literature examining cardiac structure and function in older athletes. However, a progressive accumulation of studies during the past four decades offers a body of literature worthy of systematic scrutiny.

Objectives

We conducted a systematic review, meta-analysis and meta-regression of controlled echocardiography studies comparing left ventricular (LV) structure and function in aerobically trained older athletes (> 45 years) with age-matched untrained controls, in addition to investigating the influence of chronological age.

Methods

Electronic databases were searched from inception to January 2018 before conducting a random-effects meta-analysis to calculate pooled differences in means, effect size and 95% confidence intervals (CIs). Study heterogeneity was reported using Cochran’s Q and I² statistic.

Results

Overall, 32 studies (644 athletes; 582 controls) were included. Athletes had greater LV end-diastolic diameter (3.65 mm, 95% CI 2.66–4.64), interventricular septal thickness (1.23 mm, 95% CI 0.85–1.60), posterior wall thickness (1.20 mm, 95% CI 0.83–1.56), LV mass (72 g, 95% CI 46–98), LV mass index (28.17 g·m², 95% CI 19.84–36.49) and stroke volume (13.59 mL, 95% CI 7.20–19.98) (all p < 0.01). Athletes had superior global diastolic function [ratio of early (E) to late (A) mitral inflow velocity (E/A) 0.18, 95% CI 0.13–0.24, p < 0.01; ratio of early (e′) to late (a′) diastolic annular tissue velocity (e′/a′) 0.23, 95% CI 0.06–0.40, p = 0.01], lower A (−8.20 cm·s⁻¹, 95% CI −11.90 to −4.51, p < 0.01) and a′ (−0.72 cm·s⁻¹, 95% CI −1.31 to −0.12, p = 0.02), and more rapid e′ (0.96 cm·s⁻¹, 95% CI 0.05–1.86, p = 0.04). Meta-regression for chronological age identified that athlete–control differences, in the main, are maintained during advancing age.

Conclusions

Athletic older men have larger cardiac dimensions and enjoy more favourable cardiac function than healthy, non-athletic counterparts. Notably, the athlete groups maintain these effects during chronological ageing.

Electronic supplementary material

The online version of this article (10.1007/s40279-018-1004-3) contains supplementary material, which is available to authorized users.

Special Article - Exercise-induced right ventricular injury or arrhythmogenic cardiomyopathy (ACM): The bright side and the dark side of the moon

There is still debate on the range of normal physiologic changes of the right ventricle or ventricular (RV) function in athletes. Genetic links to arrhythmogenic cardiomyopathy (ACM) are well-established. There is no current consensus on the importance of extensive exercise and exercise-induced injury to the RV. During the intensive exercise of endurance sports, the cardiac structures adapt to athletic load over time. Some athletes develop RV cardiomyopathy possibly caused by genetic predisposition, whilst others develop arrhythmias from the RV. Endurance sports lead to increased volume and pressure load in both ventricles and increased myocardial mass. The extent of volume increase and changes in myocardial structure contribute to impairment of RV function and pose a challenge in cardiovascular sports medicine. Genetic predisposition to ACM may play an important role in the risk of sudden cardiac death of athletes. In this review, we discuss and evaluate existing results and opinions. Intensive training in competitive dynamic/power and endurance sports leads to specific RV adaptation, but physiological adaptation without genetic predisposition does not necessarily lead to severe complications in endurance sports. Discriminating between physiological adaptation and pathological form of ACM or RV impairment provoked by reinforced exercise presents a challenge to clinical sports cardiologists.

Left ventricular hypertrophy in athletes: How to differentiate between hypertensive heart disease and athlete’s heart

Athlete’s heart is typically accompanied by a remodelling of the cardiac chambers induced by exercise. However, although competitive athletes are commonly considered healthy, they can be affected by cardiac disorders characterised by an increase in left ventricular mass and wall thickness, such as hypertension. Unfortunately, training-induced increase in left ventricular mass, wall thickness, and atrial and ventricular dilatation observed in competitive athletes may mimic the pathological remodelling of pathological hypertrophy. As a consequence, distinguishing between athlete’s heart and hypertension can sometimes be challenging. The present review aimed to focus on the differential diagnosis between hypertensive heart disease and athlete’s heart, providing clinical information useful to distinguish between physiological and pathological remodelling.

Left ventricular remodeling in elite and sub-elite road cyclists

Marked adaptation of left ventricular (LV) structure in endurance athletes is well established. However, previous investigations of functional and mechanical adaptation have been contradictory. A lack of clarity in subjects' athletic performance level may have contributed to these disparate findings. This study aimed to describe structural, functional, and mechanical characteristics of the cyclists' LV, based on clearly defined performance levels. Male elite cyclists (EC) (n = 69), sub-elite cyclists (SEC) (n = 30), and non-athletes (NA) (n = 46) were comparatively studied using conventional and speckle tracking 2D echocardiography. Dilated eccentric hypertrophy was common in EC (34.7%), but not SEC (3.3%). Chamber concentricity was higher in EC compared to SEC (7.11 ± 1.08 vs 5.85 ± 0.98 g/(mL)^2/3 , P < .001). Ejection fraction (EF) was lower in EC compared to NA (57 ± 5% vs 59 ± 4%, P < .05), and reduced EF was observed in a greater proportion of EC (11.6%) compared to SEC (6.7%). Global circumferential strain (GCε) was greater in EC (-18.4 ± 2.4%) and SEC (-19.8 ± 2.7%) compared to NA (-17.2 ± 2.6%) (P < .05 and P < .001). Early diastolic filling was lower in EC compared with SEC (0.72 ± 0.14 vs 0.88 ± 0.12 cm/s, P < .001), as were septal E' (12 ± 2 vs 15 ± 2 cm/s, P < .001) and lateral E' (18 ± 4 vs 20 ± 4 cm/s, P < .05). The magnitude of LV structural adaptation was far greater in EC compared with SEC. Increased GCε may represent a compensatory mechanism to maintain stroke volume in the presence of increased chamber volume. Decreased E and E' velocities may be indicative of a considerable functional reserve in EC.

Marked Disparity in Regional and Transmural Cardiac Mechanics in the Athlete's Heart

INTRODUCTION

Regional heterogeneity of the human heart plays an important role in left ventricular (LV) and right ventricular (RV) function and may contribute to enhanced myocardial efficiency in the athlete's heart.

PURPOSE

This study comprehensively characterized regional and transmural myocardial tissue deformation (strain) in recreationally active (RA) and endurance-trained (ET) men to determine if regional nonuniformity evolves alongside morphological adaptations associated with endurance training.

METHODS

Echocardiography was used to measure LV and RV global, regional (apical, mid, basal) and transmural (endocardial, epicardial) longitudinal strain in 30 endurance-trained (ET) (age, 31 ± 2 yr; body mass index, 23.1 ± 0.5 kg·m; V˙O2peak, 60.2 ± 6.5 mL·kg·min) and 30 RA (age: 29 ± 2 yr; body mass index, 23.4 ± 0.4 kg·m; V˙O2peak: 42.6 ± 4.6 mL·kg·min). Nonuniformity was characterized using apex-to-base and transmural (endocardial-to-epicardial) strain gradients.

RESULTS

Global longitudinal strain was similar in ET and RA in the left (-17.4% ± 0.4% vs -17.8% ± 0.5%, P = 0.662) and right ventricle (-25.8% ± 0.8% vs 26.4% ± 1.0%, P = 0.717). The apex-to-base strain gradient was greater in ET than RA in the left (-6.5% ± 0.7% vs -2.7% ± 0.8%, P = 0.001) and right ventricle (-9.6% ± 1.8% vs -3.0% ± 1.6%, P = 0.010). The LV transmural strain gradient was greater than RV in both groups, but similar in ET and RA (-4.7% ± 0.2% vs -4.7% ± 0.2%, P = 0.850), whereas RV transmural strain gradient was greater in ET than RA (-3.4% ± 0.3% vs -1.6% ± 0.4%, P = 0.003). RV apex-to-base and transmural strain gradients correlated with RV end-diastolic area (R = 0.536 & 0.555, respectively, P < 0.01) and V˙O2peak (R = 0.415 & 0.677, respectively, P < 0.01).

CONCLUSIONS

Transmural nonuniformity is more pronounced in the left ventricle than the RV free wall; however, RV functional nonuniformity develops markedly after endurance training. Differences in myocardial architecture and exercise-induced wall stress in the left and right ventricles are possible explanations for the marked functional nonuniformity throughout the myocardium and in response to endurance exercise training.

Early life undernutrition reduces maximum treadmill running capacity in adulthood in mice

Undernutrition during early life causes chronic disease with specific impairments to the heart and skeletal muscle. The purpose of this study was to determine the effects of early life undernutrition on adult exercise capacity as a result of cardiac and skeletal muscle function. Pups were undernourished during gestation (GUN) or lactation (PUN) using a cross-fostering nutritive mouse model. At postnatal day 21, all mice were weaned and refed a control diet. At postnatal day 67, mice performed a maximal treadmill test. Echocardiography and Doppler blood flow analysis was performed at postnatal day 72, following which skeletal muscle cross-sectional area (CSA) and fiber type were determined. Maximal running capacity was reduced (diet: P = 0.0002) in GUN and PUN mice. Left ventricular mass (diet: P = 0.03) and posterior wall thickness during systole (diet × sex: P = 0.03) of GUN and PUN mice was reduced, causing PUN mice to have reduced (diet: P = 0.04) stroke volume. Heart rate of GUN mice showed a trend (diet: P = 0.07) towards greater resting values than other groups. PUN mice had greater CSA of soleus fibers. PUN had a reduced (diet: P = 0.03) proportion of type-IIX fibers in the extensor digitorum longus (EDL) and a greater (diet: P = 0.008) percentage of type-IIB fibers in the EDL. In conclusion, gestational and postnatal undernourishment impairs exercise capacity.

Altered mitochondrial metabolism in the insulin-resistant heart

Obesity-induced insulin resistance and type 2 diabetes mellitus can ultimately result in various complications, including diabetic cardiomyopathy. In this case, cardiac dysfunction is characterized by metabolic disturbances such as impaired glucose oxidation and an increased reliance on fatty acid (FA) oxidation. Mitochondrial dysfunction has often been associated with the altered metabolic function in the diabetic heart, and may result from FA-induced lipotoxicity and uncoupling of oxidative phosphorylation. In this review, we address the metabolic changes in the diabetic heart, focusing on the loss of metabolic flexibility and cardiac mitochondrial function. We consider the alterations observed in mitochondrial substrate utilization, bioenergetics and dynamics, and highlight new areas of research which may improve our understanding of the cause and effect of cardiac mitochondrial dysfunction in diabetes. Finally, we explore how lifestyle (nutrition and exercise) and pharmacological interventions can prevent and treat metabolic and mitochondrial dysfunction in diabetes.

Influence of maternal aerobic exercise during pregnancy on fetal cardiac function and outflow

BACKGROUND

Risk factors for cardiovascular disease, the leading cause of death, have been documented in children as young as 3 years of age. Maternal environment (eg, exercise) influences fetal development and long-term health. Thus, the development of the fetal cardiovascular system during pregnancy is likely a preliminary indicator of cardiac health at birth and a proxy for the future risk of cardiovascular disease throughout life.

OBJECTIVE

The purpose of this study was to assess the effects of supervised prenatal aerobic exercise at recommended levels on fetal cardiac function and outflow in the third trimester of pregnancy. We hypothesized that fetuses of aerobically trained women compared with fetuses of nonexercising women would exhibit increased cardiac function and greater cardiac output.

STUDY DESIGN

Secondary data analyses of a 20-week, randomized controlled exercise intervention trial in pregnant women between 2015 and 2018 in Eastern North Carolina were performed. Eligibility criteria included pregnant women <16 weeks gestation, singleton pregnancy, aged 18-40 years, body mass index of 18.5-34.99 kg/m², physician clearance letter for exercise participation, reliable transportation, and method of communication. Exclusion criteria included the presence of chronic conditions (eg, type 1 or 2 diabetes mellitus), current medications known to adversely affect fetal growth (eg, antidepressants), alcohol, smoking, or illicit drug use. The patient cohort consisted of 133 eligible pregnant women who were assigned randomly to either an aerobic exercise (n=66) group that participated in 150 minutes of supervised, moderate-intensity (40-59% VO_2peak; 12-14 on Borg Rating of Perceived Exertion) aerobic exercise per week or a nonexercising group (n=61) that consisted of 150 minutes per week of light (<40% VO_2peak) stretching and relaxation breathing techniques. Between 34 and 36 weeks gestation, a fetal echocardiogram was performed to assess fetal cardiac function, which included fetal heart rate, right- and left-ventricular stroke volume, stroke volume index, cardiac output, cardiac output index, and cardiac outflow that included pulmonary and aortic valve diameters, peak flow velocity, and peak flow velocity-time integral. Fetal activity state (quiet vs active) during the echocardiogram and maternal aerobic capacity served as covariates. Intention-to-treat and per-protocol (participants who attended ≥80% of exercise sessions) analysis of covariance regression models were performed.

RESULTS

Of the 127 randomly assigned participants, 66 and 50 participants were included in the intention-to-treat and per-protocol analyses, respectively. Prenatal aerobic exercise significantly increased fetal right-ventricular cardiac measures of right ventricular stroke volume (P=.001) and stroke index via velocity-time integral (P=.003), right ventricular cardiac output (P=.002), cardiac index via velocity-time integral (P=.006), pulmonary artery diameter (P=.02), and pulmonary valve velocity-time integral (P=.03). Only in the intention-to-treat analysis was a significant difference in fetal left ventricular cardiac outflow observed; there was a greater aortic valve peak velocity (P=.04) found among fetuses of aerobically trained pregnant women. No other statistically significant between-group differences were found.

CONCLUSION

The findings of this study demonstrate that participation in prenatal aerobic exercise at recommended levels may improve fetal cardiac function and outflow parameters. Follow-up cardiovascular measures in the postnatal period are needed to determine potential long-term effects on the offspring's cardiac function and outflow.

Heart of the World's Top Ultramarathon Runner-Not Necessarily Much Different from Normal

The impact of ultramarathon (UM) runs on the organs of competitors, especially elite individuals, is poorly understood. We tested a 36-year-old UM runner before, 1–2 days after, and 10–11 days after winning a 24-h UM as a part of the Polish Championships (258.228 km). During each testing session, we performed an electrocardiogram (ECG), transthoracic echocardiography (TTE), cardiac magnetic resonance imaging (MRI), cardiac ³¹P magnetic resonance spectroscopy (³¹P MRS), and blood tests. Initially, increased cholesterol and low-density lipoprotein cholesterol (LDL-C) levels were identified. The day after the UM, increased levels of white blood cells, neutrophils, fibrinogen, alanine aminotransferase, aspartate aminotransferase, creatine kinase, C-reactive protein, and N-terminal type B natriuretic propeptide were observed. Additionally, decreases in hemoglobin, hematocrit, cholesterol, LDL-C, and hyponatremia were observed. On day 10, all measurements returned to normal levels, and cholesterol and LDL-C returned to their baseline abnormal values. ECG, TTE, MRI, and ³¹P MRS remained within the normal ranges, demonstrating physiological adaptation to exercise. The transient changes in laboratory test results were typical for the extreme efforts of the athlete and most likely reflected transient but massive striated muscle damage, liver cell damage, activation of inflammatory processes, effects on the coagulation system, exercise-associated hyponatremia, and cytoprotective or growth-regulatory effects. These results indicated that many years of intensive endurance training and numerous UMs (including the last 24-h UM) did not have a permanent adverse effect on this world-class UM runner’s body and heart. Transient post-competition anomalies in laboratory test results were typical of those commonly observed after UM efforts.

High-Intensity Interval Training Improves Left Ventricular Contractile Function

INTRODUCTION

Improved myocardial contractility is a critical circulatory adaptation to exercise training. However, the types of exercise that enhance left ventricular (LV) contractile and diastolic functions have not yet been established. This study investigated how high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) influence LV mechanics during exercise.

METHODS

Fifty-four healthy sedentary men were randomized to engage in either HIIT (3-min intervals at 40% and 80% of V˙O2max, n = 18) or MICT (sustained 60% of V˙O2max, n = 18) for 30 min·d, 5 d·wk for 6 wk or to a control group (n = 18) that did not engage in exercise intervention. LV mechanics during semiupright bicycle exercise tests were measured by two-dimensional speckle-tracking echocardiography.

RESULTS

Before the interventions, acute bicycle exercise increased (i) peak basal/apical radial and circumferential and peak longitudinal strains and strain rates, (ii) peak basal/apical rotations and torsion, and (iii) peak systolic twisting and early diastolic untwisting velocities in the LV. After the interventions, the HIIT group exhibited greater LV mass and diastolic internal diameter as well as higher ratio of E wave to A wave and early diastolic propagation velocity than did the MICT group. Despite decreased peak apical rotation and torsion, HIIT enhanced peak apical radial strain and strain rate as well as shortened the time to reach peak untwisting velocity in the LV during exercise. However, the LV mechanics during exercise were unchanged in the control group.

CONCLUSION

HIIT but not MICT induces eccentric myocardial hypertrophy. Moreover, HIIT effectively improves the LV mechanics during exercise by increasing contractile and diastolic functions.

Resistance training promotes reduction in Visceral Adiposity without improvements in Cardiomyocyte Contractility and Calcium handling in Obese Rats

Resistance training (RT) improves the cardiomyocyte calcium (Ca²⁺) cycling during excitation-contraction coupling. However, the role of RT in cardiomyocyte contractile function associated with Ca²⁺ handling in obesity is unclear. Wistar rats were distributed into four groups: control, sedentary obese, control plus RT, and obesity plus RT. The 10-wk RT protocol was used (4-5 vertical ladder climbs, 60-second interval, 3× a week, 50-100% of maximum load). Metabolic, hormonal, cardiovascular and biochemical parameters were determined. Reduced leptin levels, epididymal, retroperitoneal and visceral fat pads, lower body fat, and adiposity index were observed in RT. Obesity promoted elevation of collagen, but RT did not promote modifications of LV collagen in ObRT. RT induced elevation in maximum rates of contraction and relaxation, and reduction of time to 50% relaxation. ObRT group did not present improvement in the cardiomyocyte contractile function in comparison to Ob group. Reduced cardiac PLB serine¹⁶ phosphorylation (pPLB Ser¹⁶) and pPLB Ser¹⁶/PLB ratio with no alterations in sarcoplasmic reticulum Ca²⁺ ATPase (SERCA2a) and phospholamban (PLB) expression were observed in Ob groups. Resistance training improved body composition reduced fat pads and plasma leptin levels but did not promote positive alterations in cardiomyocyte contractile function, Ca²⁺ handling and phospholamban phosphorylation.

Left ventricular mass normalization for body size in children based on an allometrically adjusted ratio is as accurate as normalization based on the centile curves method

BACKGROUND

Normalization for body size is required for reliable left ventricular mass (LVM) evaluation, especially in children due to the large variability of body size. In clinical practice, the allometrically adjusted ratio of LVM to height raised to the power of 2.7 is often used. However, studies presenting normative LVM data for children recommend centile curves as optimal for the development of normative data. This study aimed to assess whether the allometrically adjusted LVM-to-height ratio can reliably reproduce the results of LVM normalization for height based on the centile curves method.

METHODS

Left ventricular mass was computed for 464 boys and 327 girls, 5-18 years old, based on echocardiographic examination. Normalized data representing LVM for height were developed using the centile curves construction method and two variants of the allometrically adjusted ratio method: one variant with the allometric exponents specific to the study groups, and one variant with the universal exponent of 2.7. The agreement between the allometric methods and the centile curves method was analyzed using the concordance correlation coefficient, sensitivity, and specificity.

RESULTS

For both the specific allometric variant and the universal variant, the analysis of concordance has indicated high reproducibility compared to the centile curves method. The respective coefficient values were 0.9917 and 0.9916 for girls, and 0.9886 and 0.9869 for boys. The sensitivity and specificity test has also shown high agreement. However, for girls, the sensitivity was higher for the specific variant (100% vs. 90.9%).

CONCLUSION

The results of the study show that allometric scaling of LVM for height can very reliably reproduce the results of LVM normalization for height based on the centile curves method. However, the analysis of sensitivity and specificity indicates greater agreement for the allometric normalization with the group-specific allometric exponents.

Diagnostic Differentiation Between Arrhythmogenic Cardiomyopathy and Athlete's Heart by Using Imaging

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden cardiac death (SCD) in youth and athletes. In the last decade, several studies focused on right ventricular (RV) remodeling in athletes and revealed that features of the physiological adaptation of the right heart to training, such as RV dilation, may overlap with those of ARVC. Therefore, a careful multiparametric evaluation is required for differential diagnosis in order to avoid false diagnosis of ARVC or, in contrast, fail to identify the risk of causing SCD. This review summarizes physiological adaptation of the RV to exercise and describes features that could help distinguishing between athlete's heart and ARVC.

Echocardiographic assessment of children participating in regular sports training

OBJECTIVE:

The aim of the present study was to determine the effects of a well-controlled endurance training program on cardiac functions and structures in healthy children and to define whether training hours per week and type of sports affect the training-induced cardiovascular response.

METHODS:

Echocardiographic recordings were obtained in 126 children who systematically participated in sports training for at least 1 year (study group), and the results were compared with the values obtained in 62 normal children who did not actively engage in any sports activity (control group). The two groups were comparable for age, sex, and body mass index. Study group participants were divided into two groups according to the duration of physical activity (training hours per week, <8 h and >8 h) and five groups according to the cardiovascular demand of sports type. Clinical examination, resting electrocardiogram, two-dimensional, M-mode, and Doppler echocardiography were obtained in all participants.

RESULTS:

Left ventricle wall dimensions, left atrial diameters, and aortic measurements were significantly higher in the study group. The mean mitral E/A ratio was also significantly higher in the training group than in untrained subjects (p<0.001). Echocardiographic measurements were similar between different sports type participants in the study group. However, aortic root diameter, left atrial diameter, and left ventricle posterior wall diastolic thickness were higher in children training >8 h/week than in children training <8 h/week in the study group.

CONCLUSION:

The present study showed that the echocardiographic parameters of children participating in regular sports training activities statistically significantly exceeded the parameters of untrained controls. These parameters were mostly dependent on the duration of training hours per week.

Insights from Exercise-induced Cardioprotection-from Clinical Application to Basic Research

Exercise has long been recognized as a beneficial living style for cardiovascular health. It has been applied to be a central component of cardiac rehabilitation for patients with chronic heart failure (CHF), coronary heart disease (CHD), post-acute coronary syndrome (ACS) or primary percutaneous coronary intervention (PCI), post cardiac surgery or transplantation. Although the effect of exercise is multifactorial, in this review, we focus on the specific contribution of regular exercise on the heart and vascular system. We will summarize the known result of clinical findings and possible mechanisms of chronic exercise on the cardiovascular system.

Metabolic Coordination of Physiological and Pathological Cardiac Remodeling

Metabolic pathways integrate to support tissue homeostasis and to prompt changes in cell phenotype. In particular, the heart consumes relatively large amounts of substrate not only to regenerate ATP for contraction but also to sustain biosynthetic reactions for replacement of cellular building blocks. Metabolic pathways also control intracellular redox state, and metabolic intermediates and end products provide signals that prompt changes in enzymatic activity and gene expression. Mounting evidence suggests that the changes in cardiac metabolism that occur during development, exercise, and pregnancy as well as with pathological stress (eg, myocardial infarction, pressure overload) are causative in cardiac remodeling. Metabolism-mediated changes in gene expression, metabolite signaling, and the channeling of glucose-derived carbon toward anabolic pathways seem critical for physiological growth of the heart, and metabolic inefficiency and loss of coordinated anabolic activity are emerging as proximal causes of pathological remodeling. This review integrates knowledge of different forms of cardiac remodeling to develop general models of how relationships between catabolic and anabolic glucose metabolism may fortify cardiac health or promote (mal)adaptive myocardial remodeling. Adoption of conceptual frameworks based in relational biology may enable further understanding of how metabolism regulates cardiac structure and function.

Change in Physical Activity and Cardiac Structure over 10 Years: The Multi-Ethnic Study of Atherosclerosis

INTRODUCTION

Physical activity (PA) is inversely associated with risk of heart failure and cardiovascular disease (CVD), whereas increased left ventricular (LV) mass and mass to volume (m:v) ratio are unfavorable CVD risk factors. We assessed whether changes in leisure time PA were associated with longitudinal changes in cardiac structure in a community-based population.

METHODS

We included 2779 Multi-Ethnic Study of Atherosclerosis participants, free of baseline CVD, who had available data on PA and cardiac magnetic resonance imaging at examinations 1 (2000-2002) and 5 (2010-2012). Physical activity was measured by a Typical Week PA Survey and converted to MET-minutes per week of moderate+vigorous activity. We used linear mixed effect models to estimate the associations of baseline and change in PA with baseline and change in cardiac structure, adjusting for CVD risk factors and body size.

RESULTS

At baseline, the mean age was 59 yr, 53% were women, and 58% of nonwhite race/ethnicity. During average 10-yr follow-up, and after accounting for baseline PA levels, the highest quintiles of PA increase were significantly associated with increases in LV mass (2.3 g; 95% confidence interval [CI], 0.4-4.2), LV end-diastolic volume (4.7 mL; 95% CI, 2.4-7.0), and stroke volume (3.3 mL; 95% CI, 1.6-5.1), but lower M:V ratio (-2.9; 95% CI, -5.0 to -0.8) compared with the lowest quintiles. Increasing exercise PA was associated with increases in LV diameter and reductions in M:V ratio, whereas occupational PA was associated with increases in m:v ratio. Increasing PA over 10 yr was also associated with greater risk of eccentric dilated LV hypertrophy at examination 5.

CONCLUSIONS

After accounting for baseline PA, greater positive changes in leisure-time PA levels were associated with a more eccentric-type of LV remodeling pattern over 10 yr. The clinical implications of such findings remain to be determined.

The Role of Volume Regulation and Thermoregulation in AKI during Marathon Running

BACKGROUND AND OBJECTIVES

Marathon runners develop transient AKI with urine sediments and injury biomarkers suggesting nephron damage.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

To investigate the etiology, we examined volume and thermoregulatory responses as possible mechanisms in runners' AKI using a prospective cohort of runners in the 2017 Hartford Marathon. Vitals, blood, and urine samples were collected in 23 runners 1 day premarathon and immediately and 1 day postmarathon. We measured copeptin at each time point. Continuous core body temperature, sweat sodium, and volume were assessed during the race. The primary outcome of interest was AKI, defined by AKIN criteria.

RESULTS

Runners ranged from 22 to 63 years old; 43% were men. Runners lost a median (range) of 2.34 (0.50-7.21) g of sodium and 2.47 (0.36-6.81) L of volume via sweat. After accounting for intake, they had a net negative sodium and volume balance at the end of the race. The majority of runners had increases in core body temperature to 38.4 (35.8-41)°C during the race from their baseline. Fifty-five percent of runners developed AKI, yet 74% had positive urine microscopy for acute tubular injury. Runners with more running experience and increased participation in prior marathons developed a rise in creatinine as compared with those with lesser experience. Sweat sodium losses were higher in runners with AKI versus non-AKI (median, 3.41 [interquartile range (IQR), 1.7-4.8] versus median, 1.4 [IQR, 0.97-2.8] g; P=0.06, respectively). Sweat volume losses were higher in runners with AKI versus non-AKI (median, 3.89 [IQR, 1.49-5.09] versus median, 1.66 [IQR, 0.72-2.84] L; P=0.03, respectively). Copeptin was significantly higher in runners with AKI versus those without (median, 79.9 [IQR, 25.2-104.4] versus median, 11.3 [IQR, 6.6-43.7]; P=0.02, respectively). Estimated temperature was not significantly different.

CONCLUSIONS

All runners experienced a substantial rise in copeptin and body temperature along with salt and water loss due to sweating. Sodium and volume loss via sweat as well as plasma copeptin concentrations were associated with AKI in runners.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_08_13_CJASNPodcast_19_09_.mp3.

The impact of sex, age and training on biventricular cardiac adaptation in healthy adult and adolescent athletes: Cardiac magnetic resonance imaging study

Aims

Physiological cardiac adaptation in athletes is influenced by multiple factors. This study aimed to investigate the impact of sex, age, body size, sports type and training volume on cardiac adaptation in healthy athletes with cardiac magnetic resonance imaging.

Methods

A total of 327 athletes (242 male) were studied (adults ≥18 years old; adolescents 14–18 years old). Left and right ventricular ejection fractions, end-diastolic volume, end-systolic volume, stroke volumes and masses were measured. Left ventricular end-diastolic volume/left ventricular mass, right ventricular end-diastolic volume/right ventricular mass and derived right/left ventricular ratios were determined to study balanced ventricular adaptation. Athletes were categorised as skill, power, mixed and endurance athletes.

Results

Male athletes had higher left and right ventricular volumes and masses in both adult ( n = 215 (145 male); 24 ± 5 years old) and adolescent ( n = 112 (97 male); 16 ± 1 years old) groups compared with women (all P < 0.05). In adults, male sex, age, body surface area, weekly training hours, mixed and endurance sports correlated with higher ventricular volumes and masses (all P < 0.05); and a combination of age, sex, training hours, endurance and mixed sports explained 30% of the variance of the left ventricular end-diastolic volume index ( r = 0.30), right ventricular end-diastolic volume index ( r = 0.34), right ventricular mass index ( r = 0.30); and as much as 53% of the left ventricular mass index ( r = 0.53) (all P < 0.0001). In adolescents, positive correlations were found between training hours and left ventricular hypertrophy ( r = 0.39, P < 0.0001), and biventricular dilation (left ventricular end-diastolic volume r = 0.34, P = 0.0008; right ventricular end-diastolic volume r = 0.36, P = 0.0004). In adolescents, age and body surface area did not correlate with cardiac magnetic resonance parameters.

Conclusion

There are significant sex differences in the physiological adaptation of adult and adolescent athlete’s heart; and male sex, higher training volume and endurance sports are major determinants of sports adaptation in adults.

Unaltered left ventricular mechanics and remodelling after 12 weeks of resistance exercise training – a longitudinal study in men

Previous longitudinal studies suggest that left ventricular (LV) structure is unaltered with resistance exercise training (RT) in young men. However, evidence from aerobic exercise training suggests that early changes in functional LV wall mechanics may occur prior to and independently of changes in LV size, although short-term changes in LV mechanics and structural remodelling in response to RT protocols have not been reported. Therefore, the purpose of this study was to examine the effects of RT on LV mechanics in healthy men performing 2 different time-under-tension protocols. Forty recreationally trained men (age: 23 ± 3 years) were randomized into 12 weeks of whole-body higher-repetition RT (20–25 repetitions/set to failure at ∼30%–50% 1 repetition maximum (1RM); n = 13), lower-repetition RT (8–12 repetitions/set to failure at ∼75%–90% 1RM; n = 13), or an active control period (n = 14). Speckle tracking echocardiography was performed at baseline and following the intervention period. Neither RT program altered standard measures of LV volumes (end-diastolic volume, end-systolic volume, or ejection fraction; P > 0.05) or indices of LV mechanics (total LV twist, untwisting rate, twist-to-shortening ratio, untwisting-to-twist ratio, or longitudinal strain; P > 0.05). This is the first longitudinal study to assess both LV size and mechanics after RT in healthy men, suggesting a maintenance of LV size and twist mechanics despite peripheral muscle adaptations to the training programs. These results provide no evidence for adverse LV structural or functional remodelling in response to RT in young men and support the positive role of RT in the maintenance of optimal cardiovascular function, even with strenuous RT.

Cardiac remodeling after six weeks of high-intensity interval training to exhaustion in endurance-trained men

High-intensity interval training (HIIT) improves physical performance of endurance athletes, although studies examining its cardiovascular effects are sparse. We evaluated the impact of HIIT on blood pressure, heart rate, and cardiac cavities' size and function in endurance-trained adults. Seventeen endurance-trained men underwent 24-h ambulatory blood pressure monitoring and Doppler echocardiography at baseline and after 6 wk of HIIT. Participants were divided into 2 groups [85% maximal aerobic power (HIIT₈₅), n = 8 and 115% maximal aerobic power (HIIT₁₁₅), n = 9] to compare the impact of different HIIT intensities. Ambulatory blood pressure monitoring and cardiac chambers' size and function were similar between groups at baseline. HIIT reduced heart rate (55 ± 8 vs. 51 ± 7 beats/min; P = 0.003), systolic blood pressure (121 ± 11 vs. 118 ± 9 mmHg; P = 0.01), mean arterial pressure (90 ± 8 vs. 89 ± 6 mmHg; P = 0.03), and pulse pressure (52 ± 6 vs. 49 ± 5 mmHg; P = 0.01) irrespective of training intensity. Left atrium volumes increased after HIIT (maximal: 50 ± 14 vs. 54 ± 14 mL; P = 0.02; minimal: 15 ± 5 vs. 20 ± 8 mL; P = 0.01) in both groups. Right ventricle global longitudinal strain lowered after training in the HIIT₈₅ group only (20 ± 4 vs. 17 ± 3%, P = 0.04). In endurance-trained men, 6 wk of HIIT reduced systolic blood pressure and mean arterial pressure and increased left atrium volumes irrespective of training intensity, whereas submaximal HIIT deteriorated right ventricle systolic function.NEW & NOTEWORTHY The novel findings of this study are that 6 wk of high-intensity interval training increases left atrial volumes irrespective of training intensity (85 or 115% maximal aerobic power), whereas the submaximal training decreases right ventricular systolic function in endurance-trained men. These results may help identify the exercise threshold for potential toxicity of intense exercise training for at-risk individuals and ideal exercise training regimens conferring optimal cardiovascular protection and adapted endurance training for athletes.

Normal basic 2D echocardiographic values to screen and follow up the athlete's heart from juniors to adults: What is known and what is missing. A critical review

In the last few years, multiple echocardiographic nomograms have been published. However, normal values calculated in the general population are not applicable to athletes, whose hearts may be enlarged and hypercontractile. Accordingly, athletes require specific nomograms. Our aim is to provide a critical review of echocardiographic nomograms on two-dimensional (2D) measures for athletes. We performed a systematic search in the National Library of Medicine for Medical Subject Headings and free text terms including echocardiography, athletes, normal values and nomograms. The search was refined by adding the keywords heart, sport, elite, master, children and young. Twenty-eight studies were selected for the final analysis. Our research revealed that currently available ranges of normality for athletes reported by different authors are quite consistent, with limited exceptions (e.g. atria, aorta). Numerical and methodological limitations, however, emerged. Numerical limitations included a limited sample size (e.g. < 450 subjects) of the population assessed and the paucity of data in women, non-Caucasian athletes, and junior and master athletes. Some data on M-mode measurements are available, while those for some specific structures (e.g. left atrial (LA) area and volumes, right ventricular diameters and aorta) are limited or rare (e.g. LA area). There was heterogeneity in data normalization (by gender, sport type and ethnicity) and their expression was limited to mean values (Z-scores have rarely been employed), while variability analysis was often lacking or incomplete. We conclude that comprehensive nomograms using an appropriate sample size, evaluating a complete dataset of 2D (and three-dimensional) measures and built using a rigorous statistical approach are warranted.

The impact of a 21-day ultra-endurance ride on the heart in young, adult and older adult recreational cyclists

BACKGROUND

This study assessed the acute effect of 21 days of challenging exercise on heart structure and function in recreationally active people across a range of age categories.

METHODS

15 recreationally active people completed a 21-day fundraising cycling ride (MADRIDE) over a distance of 3515 km. Twenty-four hour Holter electrocardiography and blood biochemistry analyses were performed before and after the MADRIDE.

RESULTS

Incidence of cardiac arrhythmia was higher after MADRIDE (OR: 5.93; 95% CI: 5.68-6.19), with increases in both ventricular arrhythmias (OR: 9.90; 95% CI: 9.27-10.57) and supraventricular arrhythmias (OR: 3.09; 95% CI: 2.91-3.29). Adults (OR: 11.45; 95% CI: 7.41-17.69) and older adults (OR: 10.42 95% CI 9.83-11.05) were approximately 10 times more likely to experience arrhythmias after the MADRIDE. Whereas, young participants experienced 18% less cardiac arrhythmias after MADRIDE (OR: 0.82; 95% CI: 0.75-0.90). Aortic valve max velocity was reduced (MD: -0.12 m/s; 95% CI: -0.19-0.05 m/s) and mitral valve deceleration time was slower (MD: -28.91 m/s; 95% CI: -50.97-6.84 m/s) after MADRIDE. Other structural and functional characteristics along with heart rate variability were not different after MADRIDE.

CONCLUSIONS

Multi-day challenging exercise increased the incidence of both supraventricular and ventricular arrhythmias in active adults and older adults. Increases in arrhythmia rates after MADRIDE occurred without changes in cardiac structure and autonomic control. Further exploration is necessary to identify the causes of exercise-induced cardiac arrhythmia in adult and older adults.

The impact of nine weeks swimming exercise on heart function in hypertensive and normotensive rats: role of cardiac oxidative stress

BACKGROUND

The purpose of this study was to estimate the effects of 9-week swimming training on cardiodynamic parameters and coronary flow in a rat model of high salt-induced hypertension with a special focus on the role of oxidative stress.

METHODS

Rats involved in the research were divided randomly into four groups: healthy sedentary (SA), healthy trained (TA), sedentary hypertensive (SHA) and trained hypertensive animals (THA). Trained rats were exposed to 9-week swimming training (5 days/week, 60 min/day). Additionally, in order to induce hypertension animals from SHA and THA groups were on high sodium (8% NaCl solution) diet during 4 weeks. Afterwards all rats were sacrificed and hearts were isolated and retrogradely perfused according to Langendorff technique. The following parameters of cardiac function were continuously recorded: maximum and minimum rate of pressure development in left ventricle, systolic and diastolic left ventricular pressure and heart rate. Coronary flow was measured flowmetrically. Oxidative stress markers were determined in coronary venous effluent.

RESULTS

Our findings demonstrated that 9 weeks of swimming training led to improvement of cardiac contractility, relaxation and systolic capacity of normotensive rats, while this training protocol induced enhanced diastolic function in hypertensive conditions. More pronounced effects of exercise in alleviating oxidative stress were observed in hypertensive rats.

CONCLUSIONS

Obvious beneficial exercise-induced cardiac adaptations provide scientific basis for further researches which would thoroughly clarify the mechanisms through which swimming training alters myocardial function both in healthy conditions and in the presence of chronic diseases.

Echocardiographic measurements of left ventricular end-diastolic diameter and interventricular septal diameter in collegiate football athletes at preparticipation evaluation referenced to body surface area

Background

Are borderline echocardiogram structural measurements due to physiological adaptation or pathology in college football players? The normal reference data are very limited in this population. We report left ventricular end-diastolic diameter (LVEDD) and interventricular septal diameter (IVSD) echocardiogram findings in college football athletes.

Methods and results

A retrospective cohort review of preparticipation examination transthoracic echocardiogram measurements of LVEDD and IVSD from 375 American collegiate football athletes cleared for participation from the University of Florida in 2012–2017 and University of Georgia in 2010–2015 was performed.

LVEDD and IVSD were analysed by field position (lineman, n=137; non-lineman, n=238), race (black, n=216; white, n=158) and body surface area (BSA) for associations. Values were compared with non-athlete norms, and collegiate football athlete-specific reference norm tables were created.

Twenty-one (5.6%) athletes had LVEDD and 116 (31%) had IVSD measurements above the reference normal non-athlete values. Univariate analyses indicated that the lineman position and increasing BSA were associated with larger values for LVEDD and IVSD. Black race was associated with larger IVSD values, and white race was associated with larger LVEDD values. Player position correlated strongly with BSA (r>0.7); we created normal reference tables for LVEDD and IVSD, stratified by BSA group classification (low, average and high BSA). Proposed clinical cut-offs for normal and abnormal values are reported for raw echocardiograph metrics and BSA-indexed scores.

Conclusions

A significant number of collegiate football athletes had LVEDD and IVSD values above non-athlete norms. BSA-specific normal values help clinicians interpret results for football athletes.

Performance and cardiac evaluation before and after a 3-week training camp for 400-meter sprinters - An observational, non-randomized study

Objective

To study the performance and cardiovascular function after a 3-week training camp in athletes competing in an anaerobically dominant sport.

Methods

Twenty-three competitive 400-m athletes were enrolled in this non-randomized study, 17 took part in a 3-week training camp in South-Africa (intervention), but one declined follow-up assessment, while 6 pursued in-door winter training in Sweden and served as controls. Electrocardiography, transthoracic echocardiography, blood test analyses, maximal exercise tolerance test, and a 300-m sprint test with lactate measurements ([La]peak) were performed before and after the training camp period.

Results

At baseline, there were no clinically significant pathological findings in any measurements. The training period resulted in improved 300m-sprint performance [n = 16; running time 36.71 (1.39) vs. 35.98 (1.13) s; p<0.01] and higher peak lactate values. Despite 48% more training sessions than performed on home ground (n = 6), myocardial biomarkers decreased significantly (NT-pro BNP -38%; p<0.05, troponin T -16%; p<0.05). Furthermore, resting heart rate (-7%; p<0.01) and left ventricular systolic and diastolic volumes decreased -6% (p<0.01) and -10% (p<0.05), respectively.

Conclusions

Intense physical activity at training camp improved the performance level, likely due to improved anaerobic capacity indicated by higher [La]peak. There were no clinically significant adverse cardiac changes after this period of predominantly anaerobic training.

Brief recommendations for participation in competitive sports of athletes with arterial hypertension: Summary of a Position Statement from the Sports Cardiology Section of the European Association of Preventive Cardiology (EAPC)

Owing to its undisputed multitude of beneficial effects, European Society of Cardiology guidelines advocate regular physical activity as a class IA recommendation for the prevention and treatment of cardiovascular disease. Nonetheless, competitive athletes with arterial hypertension may be exposed to an increased risk of cardiovascular events. Guidance to physicians will be given in this summary of our recently published recommendations for participation in competitive sports of athletes with arterial hypertension.

Association between Lifelong Physical Activity and Disease Characteristics in HCM

PURPOSE

Hypertrophic cardiomyopathy (HCM) is characterized by inappropriate left ventricular (LV) wall thickness. Adaptations to exercise can occasionally mimic certain HCM characteristics. However, it is unclear whether physical activity affects HCM genotype expression and disease characteristics. Consequently, we compared lifelong physical activity volumes between HCM gene carriers with and without HCM phenotype, and compared disease characteristics among tertiles of physical activity in phenotypic HCM patients.

METHODS

We enrolled n = 22 genotype positive/phenotype negative (G+/P-) HCM gene carriers, n = 44 genotype positive/phenotype positive (G+/P+) HCM patients, and n = 36 genotype negative/phenotype positive (G-/P+) HCM patients. Lifelong physical activity was recorded using a questionnaire and quantified as metabolic equivalent of task hours per week.

RESULTS

We included 102 participants (51 ± 16 yr, 49% male). Lifelong physical activity volumes were not different between G+/P+ and G+/P- subjects (16 [10-29] vs 14 [6-26] metabolic equivalent of task-hours per week, P = 0.33). Among phenotypic HCM patients, there was no difference in LV wall thickness, mass, and late gadolinium enhancement across physical activity tertiles. Patients with the highest reported physical activity volumes were younger at the time of diagnosis (tertile 1: 52 ± 14 yr, tertile 2: 49 ± 15 yr, tertile 3: 41 ± 18 yr; P = 0.03), and more often had a history of nonsustained ventricular tachycardia (4% vs 30% vs 30%, P = 0.03).

CONCLUSIONS

Lifelong physical activity volumes are not associated with genotype-to-phenotype transition in HCM gene carriers. We also found no difference in LV wall thickness across physical activity tertiles. However, the most active HCM patients were younger at the time of diagnosis and had a higher arrhythmic burden. These observations warrant further exploration of the role of exercise in HCM disease development.

Regulation of PI3K and Hand2 gene on physiological hypertrophy of heart following high-intensity interval, and endurance training

BACKGROUND

Physical training signals cardiac hypertrophy through PI3K as an upstream and Hand2 gene as a downstream agent. The present study aimed to find the role of PI3K and Hand2 gene in myocardial hypertrophy following interval and endurance training (ET).

MATERIALS AND METHODS

Twenty-four adult Wistar male rats (210-250 g) randomly divided into control, sham, high-intensity interval training (HIIT), and ET group. Swimming time in ET increased incrementally 30-75 min, whereas in HIIT, load/body weight, and time/rest ratio increased within 12 weeks. Heart morphometry, including left ventricle end systolic (LVESV) and Diastolic (LVEDV) volume, LV posterior wall (LVPW), stroke volume (SV), ejection fraction (EF), fraction shortening (%FS), pure heart weight (HW) and left ventricle weight (LVW), and PI3K and Hand2 gene expression were measured.

RESULTS

HW and LVW were significantly more than control after ET (P < 0.05) and HIIT (P < 0.05). Both of the training groups demonstrated significantly thicker LVPW (P < 0.05), SV (P < 0.05), and %FS (P < 0.05). Furthermore, PI3K concentration and Hand2 expression significantly increased in ET (P < 0.001; P < 0.001, respectively) and HIIT (P < 0.05; P < 0.001, respectively) compared to control.

CONCLUSION

It can be concluded that this training protocol caused physiological hypertrophy in both of ET and HIIT groups, whereas HIIT can be more beneficial because of shorter training time.

Cardiac adaptation to exercise training in health and disease

The heart is the primary pump that circulates blood through the entire cardiovascular system, serving many important functions in the body. Exercise training provides favorable anatomical and physiological changes that reduce the risk of heart disease and failure. Compared with pathological cardiac hypertrophy, exercise-induced physiological cardiac hypertrophy leads to an improvement in heart function. Exercise-induced cardiac remodeling is associated with gene regulatory mechanisms and cellular signaling pathways underlying cellular, molecular, and metabolic adaptations. Exercise training also promotes mitochondrial biogenesis and oxidative capacity leading to a decrease in cardiovascular disease. In this review, we summarized the exercise-induced adaptation in cardiac structure and function to understand cellular and molecular signaling pathways and mechanisms in preclinical and clinical trials.