Myocardial Adaptations to Competitive Swim Training.

PURPOSE: Swim training is performed in the prone or supine position and obligates water immersion, factors that may augment cardiac volume loading more than other endurance sports. At present, prospective data defining the cardiac responses to swim training are lacking. We therefore studied myocardial adaptations among competitive swimmers to establish a causal relationship between swim training and left ventricular (LV) remodeling. METHODS: Collegiate swimmers were studied before and after a 90-d period of training intensification. Transthoracic echocardiography was used to examine LV structural and functional adaptations under resting conditions and during an acute LV afterload challenge generated by isometric handgrip testing (IHGT). A sedentary control population was identically studied with IHGT. RESULTS: In response to a discrete period of swim training intensification, athletes (n = 17, 47% female, 19 ± 0.4 yr old) experienced eccentric LV remodeling, characterized by proportionally more chamber dilation than wall thickening, with attendant enhancements of resting LV systolic (LV twist) and diastolic (early and late phase tissue velocities) function. Compared with baseline and controls, athletes posttraining demonstrated greater systolic twist impairment during IHGT. However, training-induced LV dilation coupled with gains in diastolic function offsets this acquired systolic susceptibility to acute afterload, resulting in the relative preservation of stroke volume during IHGT. CONCLUSION: Swim training, a sport characterized by unique cardiac loading conditions, stimulates eccentric LV remodeling with the concomitant augmentation of systolic twist and diastolic relaxation. This volume-mediated cardiac remodeling appears to result in greater systolic susceptibility to acute afterload challenge. Further work is required to establish how training-induced changes in function translate to human performance and whether these are accompanied by physiologic trade-offs with relevance to common forms of heart disease.

Diagnostic Yield of Customized Exercise Provocation Following Routine Testing.

Clinical guidelines advocate for customization of exercise testing to address patient-specific diagnostic goals, including reproduction of presenting exertional symptoms. However, the diagnostic yield of adding customized exercise testing to graded exercise in patients presenting with exertional complaints has not been rigorously examined and is the focus of this study. Using prospectively collected data, we analyzed the diagnostic yield of customized additional exercise provocation following inconclusive graded exercise test with measurement of gas exchange. Additional testing was defined as "positive" if it revealed a clinically-actionable diagnosis related to the chief complaint or reproduced symptoms in the absence of an explanatory diagnosis or pathology. Of 1,110 patients who completed a graded test, 122 (11%) symptomatic patients underwent additional customized exercise testing (e.g., sprint intervals and race simulations). Compared with those who did not undergo additional testing, this group was younger (29 [interquartile range 19 to 45] vs 46 [25 to 58] year old) and disproportionately female (43% vs 27%). Presenting symptoms included palpitations (46%), lightheadedness/syncope (25%), chest pain (14%), dyspnea (11%), and exertional intolerance (3%). Additional testing was "positive" in 48 of 122 (39%) of patients by revealing a clinically actionable diagnosis in 26 of 48 (54%) or reproducing symptoms without an explanatory diagnosis in 22 of 48 (46%). In conclusion, while patient-centered customization of exercise testing is suggested by clinical guidelines, these data are the first to demonstrate that the selective addition of customized exercise provocation following inconclusive graded exercise testing improves the diagnostic yield of exercise assessment.

Endurance exercise training attenuates natriuretic peptide release during maximal effort exercise: biochemical correlates of the "athlete's heart".

Endurance exercise training (ET) stimulates eccentric left ventricular hypertrophy (LVH) with left atrial dilation. To date, the biochemical correlates of exercise-induced cardiac remodeling (EICR) remain incompletely understood. Collegiate male rowers (n = 9) were studied with echocardiography and maximal-effort cardiopulmonary exercise testing (MECPET) before and after 90 days of ET intensification. Midregional proatrial natriuretic peptide (MR-proANP), NH2-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity troponin T were measured at rest, peak MECPET, and 60 min post-MECPET at both study time points. Endurance exercise training resulted in eccentric LVH (LV mass = 102 ± 8 vs. 110 ± 11 g/m2, P = 0.001; relative wall thickness = 0.36 ± 0.04 vs. 0.37 ± 0.04, P = 0.103), left atrial dilation (74 ± 18 vs. 84 ± 15 ml, P < 0.001), and increased exercise capacity (peak V̇o2 = 53.0 ± 5.9 vs. 67.3 ± 8.2 ml·kg-1·min-1, P < 0.001). Left ventricular remodeling was characterized by an ~7% increase in LV wall thickness but only a 3% increase in LV chamber radius. The magnitude of natriuretic peptide release, examined as percent change from rest to peak exercise, was significantly lower for both MR-proANP (115 [95,127]% vs. 78 [59,87]%, P = 0.04) and NT-proBNP (46 [31,70]% vs. 27 [25,37]%, P = 0.02) after ET. Rowing-based ET and corollary EICR appear to result in an attenuated natriuretic peptide response to maximal effort exercise. This may occur as a function of decreased cardiac wall stress after ET as seen by disproportionally higher ventricular wall thickening compared with chamber dilation.NEW & NOTEWORTHY Using longitudinal pre- and postendurance training natriuretic peptide measurements, we demonstrate that the development of exercise-induced cardiac remodeling results in an attenuated natriuretic peptide response to acute bouts of maximal intensity exercise. Exercise-induced cardiac remodeling was associated with a disproportionally higher ventricular wall thickening compared with chamber dilation, a pattern that reduces cardiac wall stress. These observations advance our understanding of both the structural and biochemical adaptations that underlie the cardiovascular response to endurance training.

The Limits of Cardiac Performance: Can Too Much Exercise Damage the Heart?

Routine moderate-intensity physical activity confers numerous cardiovascular benefits and reduces all-cause mortality. However, the health impact of exercise doses that exceed contemporary physical activity guidelines remains incompletely understood, and an emerging body of literature suggests that high levels of exercise may have the capacity to damage the cardiovascular system. This review focuses on the contemporary controversies regarding high-dose exercise and cardiovascular morbidity and mortality. We discuss the limitations of available studies, explore potential mechanisms that may mediate exercise-related cardiac injury, and highlight the gaps in knowledge for future research.

Cardiovascular response to prescribed detraining among recreational athletes.

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, V̇o2peak, 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.

Blood Pressure and LV Remodeling Among American-Style Football Players.

OBJECTIVES: This study sought to determine the relationships among American-style football (ASF) participation, acquired left ventricular (LV) hypertrophy, and LV systolic function as assessed using contemporary echocardiographic parameters. BACKGROUND: Participation in ASF has been associated with development of hypertension and LV hypertrophy. To what degree these processes impact LV function is unknown. METHODS: This was a prospective, longitudinal cohort study evaluating National Collegiate Athletic Association Division I football athletes stratified by field position (linemen: n = 30; vs. nonlinemen, n = 57) before and after a single competitive season, using transthoracic echocardiography. LV systolic function was measured using complementary parameters of global longitudinal strain (GLS) (using 2-dimensional speckle-tracking) and ejection fraction (EF) (2-dimensional biplane). RESULTS: ASF participation was associated with field position-specific increases in systolic blood pressure (SBP) (a Δ SBP of 10 ± 8 mm Hg in linemen vs. a Δ SBP of 3 ± 7 mm Hg in nonlinemen; p < 0.001) and an overall increase in incident LV hypertrophy (pre-season = 8% vs. post-season = 25%, p < 0.05). Linemen who developed LV hypertrophy had concentric geometry (9 of 11 [82%]) with decreased GLS (Δ = -1.1%; p < 0.001), whereas nonlinemen demonstrated eccentric LV hypertrophy (8 of 10 [80%]) with increased GLS (Δ = +1.4%; p < 0.001). In contrast, LV ejection fraction in the total cohort, stratified by field position, was not significantly affected by ASF participation. Among the total cohort, lineman field position, post-season weight, SBP, average LV wall thickness, and relative wall thickness were all independent predictors of post-season GLS. CONCLUSIONS: ASF participation at a lineman field position may lead to a form of sport-related myocardial remodeling that is pathologic rather than adaptive. Future study will be required to determine if targeted efforts to control blood pressure, minimize weight gain, and to include an element of aerobic conditioning in this subset of athletes may attenuate this process and translate into tangible downstream health benefits.

Sudden Cardiac Death in Athletes.

There are clear health benefits to exercise; even so, patients with cardiac conditions who engage in exercise and athletic competition may on rare occasion experience sudden cardiac death (SCD). This article reviews the epidemiology and common causes of SCD in specific athlete populations. There is ongoing debate about the optimal mechanism for SCD prevention, specifically regarding the inclusion of the ECG and/or cardiac imaging in routine preparticipation sports evaluation. This controversy and contemporary screening recommendations are also reviewed.

Cardiovascular Risk and Disease Among Masters Endurance Athletes: Insights from the Boston MASTER (Masters Athletes Survey To Evaluate Risk) Initiative.

BACKGROUND: Masters athletes (MAs), people over the age of 35 that participate in competitive sports, are a rapidly growing population that may be uniquely at risk for cardiovascular (CV) disease. The objective of this study was to develop a comprehensive clinical CV profile of MA. METHODS: An electronic Internet-based survey (survey response rate = 66 %) was used to characterize a community cohort of MAs residing in Eastern Massachusetts, USA. Clinical and lifestyle factors associated with prevalent CV disease were determined using logistic regression. RESULTS: Among 591 MAs (66 % men, age = 50 ± 9 years) with 21.3 ± 5.5 years of competitive endurance sport exposure, at least one CV risk factor was present in 64 % including the following: family history of premature atherosclerosis (32 %), prior/current tobacco exposure (23 %), hypertension (12.0 %), and dyslipidemia (7.4 %). There was a 9 % (54/591) prevalence of established CV disease which was accounted for largely by atrial fibrillation (AF) and coronary atherosclerosis (CAD). Prevalent AF was associated with years of exercise exposure [adjusted odds ratio, OR (95 % confidence intervals); OR = 1.10 (1.06, 1.21)] and hypertension [OR = 1.05 (1.01, 1.10)] while CAD was associated with dyslipidemia [OR = 9.09 (2.40, 34.39)] and tobacco use [OR = 1.78 (1.34, 3.10)] but was independent of exercise exposure. CONCLUSIONS: Among MAs, AF is associated with prior exercise exposure whereas CAD is associated with typical risk factors including dyslipidemia and prior tobacco use. These findings suggest that there are numerous opportunities to improve disease prevention and clinical care in this population.

Exercise-Induced Left Ventricular Remodeling Among Competitive Athletes: A Phasic Phenomenon.

BACKGROUND: Contemporary understanding of exercise-induced cardiac remodeling is based on cross-sectional data and relatively short duration longitudinal studies. Temporal progression of exercise-induced cardiac remodeling remains incompletely understood. METHODS AND RESULTS: A longitudinal repeated-measures study design using 2-dimensional and speckle-tracking echocardiography was used to examine acute augmentation phase (AAP; 90 days) and more extended chronic maintenance phase (39 months) left ventricular (LV) structural and functional adaptations to endurance exercise training among competitive male rowers (n=12; age 18.6±0.5 years). LV mass was within normal limits at baseline (93±9 g/m(2)), increased after AAP (105±7 g/m(2); P=0.001), and further increased after chronic maintenance phase (113±10 g/m(2); P<0.001 for comparison to post-AAP). AAP LV hypertrophy was driven by LV dilation (ΔLV end-diastolic volume, 9±3 mL/m(2); P=0.004) with stable LV wall thickness (ΔLV wall thickness, 0.3±0.1 mm; P=0.63). In contrast, chronic maintenance phase LV hypertrophy was attributable to LV wall thickening (Δ LV wall thickness, 1.1±0.4 mm; P=0.004) with stable LV chamber volumes (ΔLV end-diastolic volume, 1±1 mL/m(2); P=0.48). Early diastolic peak tissue velocity increased during AAP (-11.7±1.9 versus -13.6±1.3 cm/s; P<0.001) and remained similarly increased after chronic maintenance phase. CONCLUSIONS: In a small sample of competitive endurance athletes, exercise-induced cardiac remodeling follows a phasic response with increases in LV chamber size, early diastolic function, and systolic twist in an acute augmentation phase of exercise training. This is followed by a chronic phase of adaptation characterized by increasing wall thickness and regression in LV twist. Training duration is a determinant of exercise-induced cardiac remodeling and has implications for the assessment of myocardial structure and function in athletes.

Endurance Exercise-Induced Cardiac Remodeling: Not All Sports Are Created Equal.

BACKGROUND: The term endurance sport (ES) is broadly used to characterize any exercise that requires maintenance of high cardiac output over extended time. However, the relative amount of isotonic (volume) versus isometric (pressure) cardiac stress varies across ES disciplines. To what degree ES-mediated cardiac remodeling varies, as a function of superimposed isometric stress, is uncertain. The aim of this study was to compare the cardiac remodeling characteristics associated with two common yet physiologically distinct forms of ES. METHODS: Healthy competitive male long-distance runners (high isotonic, low isometric stress; n = 40) and rowers (high isotonic, high isometric stress; n = 40) were comparatively studied after 3 months of sport-specific exercise training with conventional and speckle-tracking two-dimensional echocardiography. RESULTS: Rowers demonstrated dilated left ventricular (LV) volumes and elevated LV mass (i.e., eccentric LV hypertrophy), whereas runners demonstrated normal LV mass (runners, 88 ± 11 g/m(2); rowers, 108 ± 13 g/m(2); P < .001) despite comparatively larger LV volumes (runners, 101 ± 10 mL/m(2); rowers, 89 ± 13 mL/m(2); P < .001) consistent with eccentric LV remodeling. Increasing LV mass was associated with increased reliance on early diastolic filling (LV mass vs E'/A' ratio, R = 0.47, P < .001) indicating "mass-dependent" diastolic function. Right ventricular dilation of similar magnitude and LV systolic function, as assessed by numerous complementary indices, were similar in both groups. CONCLUSIONS: Cardiac adaptations differ significantly as a function of ES discipline. Further work is required to determine the mechanisms for this differential adaptation, to develop definitive ES discipline-specific normative values, and to evaluate the optimal therapeutic use of specific ES disciplines among patients with common cardiovascular diseases.

Myocardial adaptations to recreational marathon training among middle-aged men.

BACKGROUND: Myocardial adaptations to exercise have been well documented among competitive athletes. To what degree cardiac remodeling occurs among recreational exercisers is unknown. We sought to evaluate the effect of recreational marathon training on myocardial structure and function comprehensively. METHODS AND RESULTS: Male runners (n=45; age, 48±7 years; 64% with ≥1 cardiovascular risk factor) participated in a structured marathon-training program. Echocardiography, cardiopulmonary exercise testing, and laboratory evaluation were performed pre and post training to quantify changes in myocardial structure and function, cardiorespiratory fitness, and traditional cardiac risk parameters. Completion of an 18-week running program (25±9 miles/wk) led to increased cardiorespiratory fitness (peak oxygen consumption, 44.6±5.2 versus 46.3±5.4 mL/kg per minute; P<0.001). In this setting, there was a significant structural cardiac remodeling characterized by dilation of the left ventricle (end-diastolic volume, 156±26 versus 172±28 mL, P<0.001), right ventricle (end-diastolic area=27.0±4.8 versus 28.6±4.3 cm(2); P=0.02), and left atrium (end-diastolic volume, 65±19 versus 72±19; P=0.02). Functional adaptations included increases in both early (E'=12.4±2.5 versus 13.2±2.0 cm/s; P=0.007) and late (A'=11.5±1.9 versus 12.2±2.1 cm/s; P=0.02) left ventricular diastolic velocities. Myocardial remodeling was accompanied by beneficial changes in cardiovascular risk factors, including body mass index (27.0±2.7 versus 26.7±2.6 kg/m(2); P<0.001), total cholesterol (199±33 versus 192±29 mg/dL; P=0.01), low-density lipoprotein (120±29 versus 114±26 mg/dL; P=0.01), and triglycerides (100±52 versus 85±36 mg/dL; P=0.02). CONCLUSIONS: Among middle-aged men, recreational marathon training is associated with biventricular dilation, enhanced left ventricular diastolic function, and favorable changes in nonmyocardial determinants of cardiovascular risk. Recreational marathon training may, therefore, serve as an effective strategy for decreasing incident cardiovascular disease.

Impact of American-style football participation on vascular function.

Although hypertension is common in American-style football (ASF) players, the presence of concomitant vascular dysfunction has not been previously characterized. We sought to examine the impact of ASF participation on arterial stiffness and to compare metrics of arterial function between collegiate ASF participants and nonathletic collegiate controls. Newly matriculated collegiate athletes were studied longitudinally during a single season of ASF participation and were then compared with healthy undergraduate controls. Arterial stiffness was characterized using applanation tonometry (SphygmoCor). ASF participants (n = 32, 18.4 ± 0.5 years) were evenly comprised of Caucasians (n = 14, 44%) and African-Americans (n = 18, 56%). A single season of ASF participation led to an increase in central aortic pulse pressure (27 ± 4 vs 34 ± 8 mm Hg, p <0.001). Relative to controls (n = 47), pulse wave velocity was increased in ASF participants (5.6 ± 0.7 vs 6.2 ± 0.9 m/s, p = 0.002). After adjusting for height, weight, body mass index, systolic blood pressure, and diastolic blood pressure, ASF participation was independently predictive of increased pulse wave velocity (ß = 0.33, p = 0.04). In conclusion, ASF participation leads to changes in central hemodynamics and increased arterial stiffness.

ECG findings in competitive rowers: normative data and the prevalence of abnormalities using contemporary screening recommendations.

BACKGROUND/AIM: The international governing body for competitive rowing recently mandated the inclusion of 12-lead ECG during preparticipation screening. We therefore sought to describe normative ECG characteristics and to examine the prevalence of abnormal ECG findings as defined by contemporary athlete ECG interpretation criteria among competitive rowers. METHODS: Competitive rowers (n=330, 56% male) underwent standard 12-lead ECG at the time of collegiate preparticipation screening. ECGs were analysed quantitatively to develop a sport-specific normative database and then for the presence of abnormalities in accordance with the 2010 European Society of Cardiology (ESC) recommendations and 2013 'Seattle Criteria.' RESULTS: 94% of rowers had one or more training-related ECG patterns including sinus bradycardia (51%), sinus arrhythmia (55%), and incomplete right bundle branch block (42%). Males were more likely than females to have isolated voltage criteria for left ventricular hypertrophy (LVH) (51% vs 8%, p<0.001) and early repolarisation pattern (76% vs 23%, p<0.001). Application of the 2010 ESC criteria, compared to the Seattle criteria, resulted in the classification of a significantly greater number of abnormal ECGs (47% vs 4%; p<0.001). The detection of true pathology, accomplished by both interpretation criteria, was confined to a single case of ventricular pre-excitation. CONCLUSIONS: Training-related ECG patterns with several gender-based differences are common among competitive rowers. The diagnostic accuracy and down-stream clinical implications of ECG-inclusive preparticipation screening among rowers will be dictated by the choice and future refinement of ECG interpretation criteria.

Blood pressure and left ventricular hypertrophy during American-style football participation.

BACKGROUND: Hypertension, a strong determinant of cardiovascular disease risk, has been documented among elite, professional American-style football (ASF) players. The risk of increased blood pressure (BP) and early adulthood hypertension among the substantially larger population of collegiate ASF athletes is not known. METHODS AND RESULTS: We conducted a prospective, longitudinal study to examine BP, the incidence of hypertension, and left ventricular remodeling among collegiate ASF athletes. Resting BP and left ventricular structure were assessed before and after a single season of competitive ASF participation in 6 consecutive groups of first-year university athletes (n=113). ASF participation was associated with significant increases in systolic BP (116±8 versus 125±13 mm Hg; P<0.001) and diastolic BP (64±8 mm Hg versus 66±10 mm Hg; P<0.001). At the postseason assessment, the majority of athletes met criteria for Joint National Commission (seventh report) prehypertension (53 of 113, 47%) or stage 1 hypertension (16 of 113, 14%). Among measured characteristics, lineman field position, intraseason weight gain, and family history of hypertension were the strongest independent predictors of postseason BP. Among linemen, there was a significant increase in the prevalence of concentric left ventricular hypertrophy (2 of 64 [3%] versus 20 of 64 [31%]; P<0.001) and change in left ventricular mass correlated with intraseason change in systolic BP (R=0.46, P<0.001). CONCLUSIONS: Collegiate ASF athletes may be at risk for clinically relevant increases in BP and the development of hypertension. Enhanced surveillance and carefully selected interventions may represent important opportunities to improve later-life cardiovascular health outcomes in this population.

The feasibility, diagnostic yield, and learning curve of portable echocardiography for out-of-hospital cardiovascular disease screening.

BACKGROUND: The reduction in the size of full-capability echocardiographic machines facilitates "out-of-hospital" transthoracic echocardiography (TTE). Data documenting the feasibility, yield, and logistical considerations of out-of-hospital TTE for preparticipation evaluation of athletes are sparse. METHODS: A multiyear study was conducted to examine the role of 12-lead electrocardiography for athlete screening in which TTE was used to document or exclude underlying structural heart disease. Using a commercially available portable transthoracic echocardiographic system, the rate of technically adequate imaging, diagnostic yield, and the time required for the completion of TTE (including setup, performance, and interpretation) were examined. TTE was performed in university medical offices and at "out-of-office" athletic facilities. Measurements were recorded during each year of the study to determine the impact of targeted attempts to improve efficiency. RESULTS: Four hundred sixty-seven of 510 participants had transthoracic echocardiographic images that were technically adequate for complete interpretation (imaging success rate, 92%). Echocardiographic evidence of physiologic, exercise-induced cardiac remodeling was observed in 110 of 510 (22%). Cardiac abnormalities with relevance to sports participation risk were detected in 11 of 508 participants (2.2%). Over 3 years, the average time for the completion of TTE (including setup, imaging, and interpretation) decreased (year 1, 17.4 ± 3 min; year 2, 14.0 ± 2.1 min; year 3, 11.0 ± 1.8 min; P < .001). This was driven by a significant decrease in the time required for TTE at out-of-office athletic facilities. CONCLUSIONS: Community-based TTE in athletes is feasible and is associated with a high rate of technically adequate imaging. Importantly, there appears to be a significant learning curve associated with out-of-hospital TTE.