Does the human heart fatigue subsequent to prolonged exercise?

Impact of High Intensity Contact Physical Activity During a Match on Echocardiographic Parameters and High-Sensitivity Troponin I in Competitive Rugby Players

Background/Objectives: High-intensity physical activity, especially in contact sports, may have harmful effect on athletes' health. The aim of the study is to determine acute changes in the function of the left ventricle in rugby players after a competitive match. Methods: A prospective, clinical, observational case-control study was conducted. All cases were European Caucasian male athletes, older than 18 years, who had played for at least 60 min in the investigated match. A transthoracic echocardiography and blood tests were performed in all the participants two days before the match and within one hour after the match. Results: The total number of examinees was 34. Out of the 31 measured echocardiographic parameters, 22 showed a statistically significant change before and after the match. We also observed changes in echocardiographic parameters in relation to the increase in high-sensitivity troponin I. Two-dimensional left ventricle (LV) end-systolic (75 ± 10.5 vs. 67.1 ± 10 mL, p = 0.032) and LV end-diastolic (149.7 ± 24.6 vs. 133.8 ± 13.3 mL, p = 0.020) volumes, 3D LV end-systolic volume (75.8 ± 9.2 vs. 67.4 ± 9.5 mL, p = 0.014), indexed 2D LV end-diastolic volume (67.6 ± 9.3 vs. 61.4 ± 8 mL, p = 0.042), and indexed 3D LV end-systolic (34.3 ± 3.8 vs. 31 ± 4.8 mL, p = 0.033) volume after the match were significantly higher in players with troponin increase. Conclusions: High-intensity contact activity, such as rugby, leads to acute changes in echocardiographic parameters, especially in athlete's who experience elevation in troponin.

Coordinated Metabolic Responses Facilitate Cardiac Growth in Pregnancy and Exercise

PURPOSE OF REVIEW

Pregnancy and exercise are systemic stressors that promote physiological growth of the heart in response to repetitive volume overload and maintenance of cardiac output. This type of remodeling is distinct from pathological hypertrophy and involves different metabolic mechanisms that facilitate growth; however, it remains unclear how metabolic changes in the heart facilitate growth and if these processes are similar in both pregnancy- and exercise-induced cardiac growth.

RECENT FINDINGS

The ability of the heart to metabolize a myriad of substrates balances cardiac demands for energy provision and anabolism. During pregnancy, coordination of hormonal status with cardiac reductions in glucose oxidation appears important for physiological growth. During exercise, a reduction in cardiac glucose oxidation also appears important for physiological growth, which could facilitate shuttling of glucose-derived carbons into biosynthetic pathways for growth. Understanding the metabolic underpinnings of physiological cardiac growth could provide insight to optimize cardiovascular health and prevent deleterious remodeling, such as that which occurs from postpartum cardiomyopathy and heart failure. This short review highlights the metabolic mechanisms known to facilitate pregnancy-induced and exercise-induced cardiac growth, both of which require changes in cardiac glucose metabolism for the promotion of growth. In addition, we mention important similarities and differences of physiological cardiac growth in these models as well as discuss current limitations in our understanding of metabolic changes that facilitate growth.

Stroke volume response during prolonged exercise depends on left ventricular filling: evidence from a β-blockade study

Prolonged moderate-intensity exercise leads to a progressive upward drift in heart rate (HR) that may compromise stroke volume (SV). Alternatively, the HR drift may be related to abated SV due to impaired ventricular function. The aim of this study was to examine the effects of cardiovascular drift on left ventricular volumes and in turn SV. Thirteen healthy young males completed two 60-min cycling bouts on a semirecumbent cycle ergometer at 57% maximal oxygen consumption (V̇o2max) either under placebo condition (CON) or after ingesting a small dose of β1-blockers (BB). Measurements of HR, end-diastolic volume (EDV), and end-systolic volume were obtained by echocardiography and used to calculate SV. Other variables such as ear temperature, skin temperature, blood pressure, and blood volume were measured to assess potential changes in thermoregulatory needs and loading conditions. HR drift was successfully prevented when using BB from min 10 to min 60 (128 ± 9 to 126 ± 8 beats/min, P = 0.29) but not in CON (134 ± 10 to 148 ± 10 beats/min, P < 0.01). Conversely, during the same time, SV increased by 13% when using BB (103 ± 9 to 116 ± 7 mL, P < 0.01), whereas it was unchanged in CON (99 ± 7 to 101 ± 9 mL, P = 0.37). The SV behavior was mediated by a 4% increase in EDV in the BB condition (164 ± 18 to 170 ± 18 mL, P < 0.01), whereas no change was observed in the CON condition (162 ± 18 to 160 ± 18 mL, P = 0.23). In conclusion, blocking HR drift enhances EDV and SV during prolonged exercise. These findings suggest that SV behavior is tightly related to filling time and loading conditions of the left ventricle.

May Strenuous Endurance Sports Activity Damage the Cardiovascular System of Healthy Athletes? A Narrative Review

The positive effects of physical activity are countless, not only on the cardiovascular system but on health in general. However, some studies suggest a U-shape relationship between exercise volume and effects on the cardiovascular system. On the basis of this perspective, moderate-dose exercise would be beneficial compared to a sedentary lifestyle, while very high-dose physical activity would paradoxically be detrimental. We reviewed the available evidence on the potential adverse effects of very intense, prolonged exercise on the cardiovascular system, both acute and chronic, in healthy athletes without pre-existing cardiovascular conditions. We found that endurance sports activities may cause reversible electrocardiographic changes, ventricular dysfunction, and troponin elevation with complete recovery within a few days. The theory that repeated bouts of acute stress on the heart may lead to chronic myocardial damage remains to be demonstrated. However, male veteran athletes with a long sports career show an increased prevalence of cardiovascular abnormalities such as electrical conduction delay, atrial fibrillation, myocardial fibrosis, and coronary calcifications compared to non-athletes. It must be underlined that the cause-effect relationship between such abnormalities and the exercise and, most importantly, the prognostic relevance of such findings remains to be established.

Impact of long-lasting moderate-intensity stage cycling event on cardiac function in young female athletes: A case study

PURPOSE

Effects of intense and/or prolonged exercise have been studied extensively in male athletes. Nevertheless, data are scare on the effect of long duration events on cardiac function in female athletes. Our aim was to investigate the effect of a long-lasting moderate-intensity stage cycling event on cardiac function of young female athletes.

METHODS

Seven well-trained female cyclists were included. They completed a cycling event of 3529 km on 23 days. All underwent an echocardiography on 6 time-points (baseline and at the arrival of day (D) 3, 7, 12, 13 and 23). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. Daily exercise load was determined by heart rate (HR), power output and rate of perceived exertion data (RPE, Borg scale).

RESULTS

All stages were mainly done at moderate intensity (average HR: 65% of maximal, average aerobic power output: 36% of maximal, average RPE: 4). Resting HR measured at the time of echocardiography did not vary during the event. Resting cardiac dimensions did not significantly change during the 23 days of cycling. No significant modification of cardiac function, whatever the studied cavity, were observed all along the event.

CONCLUSION

The results suggest that, in the context of our case study, the long-lasting moderate-intensity stage cycling event was not associated with cardiac function alteration. Nevertheless, we must be careful in interpreting them due to the limits of an underpowered study.

The Acute Effects of an Ultramarathon on Atrial Function and Supraventricular Arrhythmias in Master Athletes

BACKGROUND

Endurance sports practice has significantly increased over the last decades, with a growing proportion of master athletes. However, concerns exist regarding the potential proarrhythmic effects induced by ultra-endurance sports. This study aimed to analyse the acute effects of an ultramarathon race on atrial remodelling and supraventricular arrhythmias in a population of master athletes.

METHODS

Master athletes participating in an ultramarathon (50 km, 600 m of elevation gain) with no history of heart disease were recruited. A single-lead ECG was recorded continuously from the day before to the end of the race. Echocardiography and 12-lead resting ECG were performed before and immediately at the end of the race.

RESULTS

The study sample consisted of 68 healthy non-professional master athletes. Compared with baseline, P wave voltage was higher after the race (p < 0.0001), and more athletes developed ECG criteria for right atrial enlargement (p < 0.0001). Most of the athletes (97%) had ≥1 premature atrial beats (PAB) during the 24-h monitoring, also organised in triplets (17%) and non-sustained supraventricular tachycardias (NSSVTs) (19%). In contrast, exercise-induced PABs, triplets, and NSSVTs were rare. One athlete developed acute atrial fibrillation during the race. After the race, no significant differences were found in biatrial dimensions. Biatrial function, estimated by peak atrial longitudinal and contraction strains, were normal both before and after the race.

CONCLUSIONS

In master athletes running an ultramarathon, acute exercise-induced atrial dysfunction was not detected, and exercise-induced supraventricular arrhythmias were uncommon. These results did not confirm the hypothesis of an acute atrial dysfunction induced by ultra-endurance exercise.

Acute Effects of Heart Rate-Controlled Exergaming on Vascular Function in Young Adults

Objective: Acute and regular moderate-intensity endurance exercise (MIEE) is known to positively affect vascular function. The present study assessed if an exercise session in an innovative exergame called the ExerCube can induce similar vascular reactions as an MIEE session. Materials and Methods: Twenty-eight healthy recreationally active participants (13 females and 15 males; aged 24.8 ± 3.9 years; with body mass index 23.2 ± 2.3 kg/m²) completed an exergaming session (EGS) in the ExerCube (25 minutes) and an MIEE session on a treadmill (35 minutes, 65%-70% of maximal heart rate [HR]) in a randomized order. Both before and throughout the 45 minutes after the training sessions, pulse wave velocity (PWV), total peripheral resistance (TPR), stroke volume (SV), and HR were recorded. The study was approved by the Research Ethics Board of the Martin-Luther-Universität Halle-Wittenberg (Medical Faculty of the Martin-Luther-Universität 2019-177). Results: There were different hemodynamic responses to both types of exercises. PWV was significantly decreased 45 minutes after the EGS (P < 0.001). No significant changes were detected after MIEE (P = 0.109). TPR was significantly lower after both exercise sessions (P < 0.01). Only the EGS resulted in a significant decrease in SV 15 minutes after exercise (P < 0.001). The HR was significantly (P < 0.05) higher after both exercise sessions. After the EGS, the increase in HR was still significantly higher (P = 0.011) 45 minutes after the session. The interaction effects revealed significant differences in PWV (15 minutes, P = 0.035; 30 minutes, P = 0.004; and 45 minutes, P < 0.001), favoring the EGS. Conclusion: The EGS seems to induce a relevant exercise stimulus that can modulate vascular function. Therefore, this exergame may present an effective tool for prevention of cardiovascular diseases.

A new perspective on cardiovascular drift during prolonged exercise

Prolonged exercise induces cardiovascular drift, which is characterized by decreasing mean arterial pressure (MAP), stroke volume and heart rate increase. Cardiovascular drift has been debated for a long time. Although the exact mechanisms underlying cardiovascular drift are still unknown, two theories have been proposed. The first is that increased skin blood flow displaces blood volume from central circulation to the periphery, which reduces stroke volume. According to this theory, the rise in heart rate is presumably responding to the drop in stroke volume and MAP. The alternative theory is that an increase in heart rate is due to an increase in sympathetic nervous activity causing reducing time at diastole, and therefore stroke volume. It may be difficult to determine a single robust factor accounting for cardiovascular drift, due to the broad range of circumstances. The primary focus of this review is to elucidate our understanding of cardiovascular drift during prolonged exercise through nitric oxide and force-frequency relationship. We highlight for the very first time that cardiovascular drift (in some conditions and within a specific time period) may be considered as a protective strategy against potential damage that could be induced by the intense and prolonged contraction of the myocardium.

The acute effects of an ultramarathon on biventricular function and ventricular arrhythmias in master athletes

AIMS

Endurance sports practice has significantly increased over the last decades, with a growing proportion of participants older than 40 years. Although the benefits of moderate regular exercise are well known, concerns exist regarding the potential negative effects induced by extreme endurance sport. The aim of this study was to analyse the acute effects of an ultramarathon race on the electrocardiogram (ECG), biventricular function, and ventricular arrhythmias in a population of master athletes.

METHODS AND RESULTS

Master athletes participating in an ultramarathon (50 km, 600 m of elevation gain) with no history of heart disease were recruited. A single-lead ECG was recorded continuously from the day before to the end of the race. Echocardiography and 12-lead resting ECG were performed before and at the end of the race. The study sample consisted of 68 healthy non-professional master athletes. Compared with baseline, R-wave amplitude in V1 and QTc duration were higher after the race (P < 0.001). Exercise-induced isolated premature ventricular beats were observed in 7% of athletes; none showed non-sustained ventricular tachycardia before or during the race. Left ventricular ejection fraction, global longitudinal strain (GLS), and twisting did not significantly differ before and after the race. After the race, no significant differences were found in right ventricular inflow and outflow tract dimensions, fractional area change, s', and free wall GLS.

CONCLUSION 

In master endurance athletes running an ultra-marathon, exercise-induced ventricular dysfunction, or relevant ventricular arrhythmias was not detected. These results did not confirm the hypothesis of a detrimental acute effect of strenuous exercise on the heart.

The Effect of Omega-3 Fatty Acid Supplementation on Serum Adipocytokines, Lipid Profile and Biochemical Markers of Inflammation in Recreational Runners

BACKGROUND

The study aimed to evaluate the effects of a 3-week ω-3 PUFA supplementation on serum adipocytokines (i.e., adiponectin, leptin), neuregulin-4 (NRG4) and erythrocyte omega-3 (ω-3) fatty acid content, as well as the blood antioxidant defense capacity in non-elite endurance runners.

METHODS

Twenty-four runners were randomized into two groups: the supplemented group, who received omega free fatty acids extract containing 142 mg of EPA, 267 mg of DHA, 12 mg of vitamin E and 5 µg of vitamin D, each administrated at a dose of six capsules twice a day for three weeks, or the placebo group. Venous blood samples were withdrawn at the start and at the end of the study protocols to estimate serum biochemical variables.

RESULTS

A significantly higher ω-3 index and lower AA/EPA ratio was observed after ω-3 PUFA compared to pre-supplementation levels (p < 0.001 and p < 0.001, respectively). An increase in baseline adiponectin and NRG4 levels, as well as a decrease of leptin concentration and lipid profile improvement, were observed in subjects after a ω-3 PUFA diet. The increased ω-3 index had a significant effect on TNFα levels and a serum marker of antioxidant defense.

CONCLUSIONS

The ω-3 PUFA extract with added vitamin E and D supplementation may have a positive effect on the function of the adipocyte tissue, as well as the ability to prevent cardiovascular complications in athletes.

The Effect of Exercise on the Older Adult's Blood Pressure Suffering Hypertension: Systematic Review and Meta-Analysis on Clinical Trial Studies

BACKGROUND

Senescence refers to spontaneous and progressive irreversible degenerative changes in which both the physical and psychological power diminish significantly. Hypertension is the most common cardiovascular disease in the elderly. Several studies have been conducted regarding the effect of exercise on reducing the blood pressure of the elderly, which have found contradictory results. One of the uses of meta-analysis study is responding to these assumptions and resolving the discrepancies. Accordingly, the aim of the present study is to determine the impact of exercise on the blood pressure of older adults.

METHOD

In this research, in order to find electronic published papers from 1992 to 2019, the papers published in both domestic and foreign databases including SID, MagIran, IranMedex, IranDox, Gogole Scholar, Cohrane, Embase, Science Direct, Scopus, PubMed, and Web of Science (ISI) were used. Heterogeneity index between the studies was determined based on Cochran test Q(c) and I 2. Considering existence of heterogeneity, random effects model was employed to estimate the standardized subtraction of the mean exercise test score for reduction of blood pressure in the older adults across the intervention group before and after the test.

RESULTS

In this meta-analysis and systematic review, eventually 69 papers met the inclusion criteria. The total number of participants was 2272 in the pre- and postintervention groups when examining the systolic changes and 2252 subjects in the pre- and postintervention groups when inspecting the diastolic changes. The standardized mean difference in examining the systolic changes before the intervention was 137.1 ± 8.09 and 132.98 ± 0.96 after the intervention; when exploring the diastolic changes, the pre- and postintervention values were 80.3 ± 0.85 and 76.0 ± 6.56, respectively, where these differences were statistically significant (P < 0.01).

CONCLUSION

The results of this study indicated that exercise leads to significant reduction in both systolic and diastolic blood pressure. Accordingly, regular exercise can be part of the treatment plan for hypertensive elderly.

Myocardial Injury and Overload among Amateur Marathoners as Indicated by Changes in Concentrations of Cardiovascular Biomarkers

Marathons continue to grow in popularity among amateurs. However, the impact of intensive exercise on the amateur's cardiovascular system has not yet been studied. Analysis of the influence of the marathon on kinetics of biomarkers reflecting cardiac injury and overload may bring new insights into this issue. We investigated the effect of running a marathon on the concentrations of high sensitivity cardiac troponin I (hs-cTnI), heart-type fatty acid binding protein (H-FABP), N-terminal proatrial natriuretic peptide (NT-proANP), B-type natriuretic peptide (BNP), growth differentiation factor 15 (GDF-15) and galectin 3 (Gal-3) in the population of male amateur runners. The study included 35 amateur marathoners and followed 3 stages: S1-two weeks prior to the marathon, S2-at the finish line and S3-two weeks after. Blood samples were collected at each stage and analyzed for biomarkers and laboratory parameters. Concentrations of all studied biomarkers were significantly higher at S2, whereas at S3 did not differ significantly compared to S1. Running a marathon by an amateur causes an acute rise in biomarkers of cardiac injury and stress. Whether repetitive bouts of intensive exercise elicit long-term adverse cardiovascular effects in amateur marathoners needs further research.

Impact of ultra-marathon and marathon on biomarkers of myocyte necrosis and cardiac congestion: a prospective observational study

BACKGROUND

An elevation of cardiac biomarkers is observed after intense or long-lasting physical activity. However, a recent meta-analysis has suggested that there might be an inverse relationship between duration of exercise and degree of biomarker elevation. The objective of this observational study was to investigate the impact of ultra-marathon (UM) vs. marathon (M) on biomarkers of myocyte necrosis and hemodynamic stress/congestion.

METHODS

Well-trained endurance athletes were recruited to participate in a 130-km UM and a M run. Troponin I (TnI), creatine kinase (CK), N-terminal pro-brain natriuretic peptide (NT-proBNP), mid-regional pro-adrenomedullin (MR-proADM), and copeptin were measured after both events, respectively.

RESULTS

Fifteen athletes (14 males, one female) were included. There was no difference in exercise intensity according to the Borg scale (UM 16 [IQR 15-17], M 16 [IQR 14-17]; p = 0.424). Biomarkers of myocyte necrosis both differed significantly with higher levels of TnI (UM 0.056 ng/L [IQR 0.022-0.104), M 0.028 ng/L [IQR 0.022-0.049]; p = 0.016) and CK (UM 6992 U/l [IQR 2886-23038], M 425 U/l [IQR 327-681]; p = 0.001) after UM compared to M. Also, NT-proBNP (UM 723 ng/L [IQR 378-1152], M 132 ng/L [IQR 64-198]; p = 0.001) and MR-proADM (UM 1.012 nmol/L [IQR 0.753-0.975], M 0.877 nmol/L [IQR 0.550-0.985]; p = 0.023) as markers of myocardial congestion were significantly higher after UM. There was a tendency for elevated copeptin levels after M, but did not reach statistical significance (p = 0.078).

CONCLUSION

Ultra-marathon is associated with higher levels of biomarkers of myocyte necrosis and cardiac congestion compared to marathon, highlighting the impact of exercise duration on the cardiovascular system.

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.

A novel traditional Chinese medicine ameliorates fatigue-induced cardiac hypertrophy and dysfunction via regulation of energy metabolism

Prolonged exercise and exercise training can adversely affect cardiac function in some individuals. QiShenYiQi Pills (QSYQ), which are a compound Chinese medicine, have been previously shown to improve pressure overload-induced cardiac hypertrophy. We hypothesized that QSYQ can ameliorate as well the fatigue-induced cardiac hypertrophy. This study was to test this hypothesis and underlying mechanism with a focus on its role in energy regulation. Male Sprague-Dawley rats were used to establish exercise adaptation and fatigue model on a motorized rodent treadmill. Echocardiographic analysis and heart function test were performed to assess heart systolic function. Food-intake weight/body weight and heart weight/body weight were assessed, and hematoxylin and eosin staining and immunofluorescence staining of myocardium sections were performed. ATP synthase expression and activity and ATP, ADP, and AMP levels were assessed using Western blot and ELISA. Expression of proteins related to energy metabolism and IGF-1R signaling was determined using Western blot. QSYQ attenuated the food-intake weight/body weight decrease, improved myocardial structure and heart function, and restored the expression and distribution of myocardial connexin 43 after fatigue, concomitant with an increased ATP production and a restoration of metabolism-related protein expression. QSYQ upgraded the expression of IGF-1R, P-AMPK/AMPK, peroxisome proliferator-activated receptor-γ coactivator-1α, nuclear respiratory factor-1, P-phosphatidylinositol 3-kinase (PI3K)/PI3K, and P-Akt/Akt thereby attenuated the dysregulation of IGF-1R signaling after fatigue. QSYQ relieved fatigue-induced cardiac hypertrophy and enhanced heart function, which is correlated with its potential to improve energy metabolism by regulating IGF-1R signaling. NEW & NOTEWORTHY Prolonged exercise may impact some people leading to pathological cardiac hypertrophy. This study using an animal model of fatigue-induced cardiac hypertrophy provides evidence showing the potential of QiShenYiQi Pills, a novel traditional Chinese medicine, to prevent the cardiac adaptive hypertrophy from development to pathological hypertrophy and demonstrates that this effect is correlated with its capacity for regulating energy metabolism through interacting with insulin-like growth factor-1 receptor.

Metabolic Mechanisms of Exercise-Induced Cardiac Remodeling

Exercise has a myriad of physiological benefits that derive in part from its ability to improve cardiometabolic health. The periodic metabolic stress imposed by regular exercise appears fundamental in driving cardiovascular tissue adaptation. However, different types, intensities, or durations of exercise elicit different levels of metabolic stress and may promote distinct types of tissue remodeling. In this review, we discuss how exercise affects cardiac structure and function and how exercise-induced changes in metabolism regulate cardiac adaptation. Current evidence suggests that exercise typically elicits an adaptive, beneficial form of cardiac remodeling that involves cardiomyocyte growth and proliferation; however, chronic levels of extreme exercise may increase the risk for pathological cardiac remodeling or sudden cardiac death. An emerging theme underpinning acute as well as chronic cardiac adaptations to exercise is metabolic periodicity, which appears important for regulating mitochondrial quality and function, for stimulating metabolism-mediated exercise gene programs and hypertrophic kinase activity, and for coordinating biosynthetic pathway activity. In addition, circulating metabolites liberated during exercise trigger physiological cardiac growth. Further understanding of how exercise-mediated changes in metabolism orchestrate cell signaling and gene expression could facilitate therapeutic strategies to maximize the benefits of exercise and improve cardiac health.

Left ventricular function and mechanics following prolonged endurance exercise: an update and meta-analysis with insights from novel techniques

Background

The cardiac consequences of undertaking endurance exercise are the topic of recent debate. The purpose of this review is to provide an update on a growing body of literature, focusing on left ventricular (LV) function following prolonged endurance exercise over 2 h in duration which have employed novel techniques, including myocardial speckle tracking, to provide a more comprehensive global and regional assessment of LV mechanics.

Methods

Prospective studies were filtered independently following a pre-set criteria, resulting in the inclusion of 27 studies in the analyses. A random-effects meta-analysis was used to determine the weighted mean difference and 95% confidence intervals (CI) of LV functional and mechanical data from pre-to-post-exercise. Narrative commentary was also provided where volume of available evidence precluded meta-analysis.

Results

A significant overall reduction in LV longitudinal strain (Ɛ) n = 22 (− 18 ± 1 to − 17 ± 1%; effect size (d) − 9: − 1 to − 0.5%), strain rate n = 10 (SR;d − 0.9: − 0.1.3 to − 0.5 l/s) and twistn = 5 (11.9 ± 2.2 to 8.7 ± 2.2°,d − 1: − 1.6 to − 0.3°) was observed following strenuous endurance exercise (range 120–1740 min) (P < 0.01). A smaller number of studies (n = 4) also reported a non-significant reduction in global circumferential and radial Ɛ (P > 0.05).

Conclusion

The meta-analysis and narrative commentary demonstrated that a reduction in LV function and mechanics is evident following prolonged endurance exercise. The mechanism(s) responsible for these changes are complex and likely multi-factorial in nature and may be linked to right and left ventricular interaction.

Long-term leucine supplementation aggravates prolonged strenuous exercise-induced cardiovascular changes in trained rats

NEW FINDINGS

What is the central question of this study? Can long-term leucine supplementation prevent prolonged strenuous endurance exercise induced cardiac injury? What is the main finding and its importance? Prolonged endurance exercise does not seem to exceed cardiac energetic capacity, hence it does not represent an energy threat to this organ, at least in trained subjects. However, it may induce, in susceptible individuals, a state of cardiac electrical instability, which has been associated with ventricular arrhythmias and sudden cardiac death. This situation might be worsened when combined with leucine supplementation, which leads to increased blood pressure and cardiac injury. Leucine supplementation failed to prevent cardiac fatigue symptoms and may aggravate prolonged strenuous exercise-induced cardiovascular disturbances in trained rats. Observational studies have raised concerns that prolonged strenuous exercise training may be associated with increased risk of cardiac arrhythmia and even primary cardiac arrest or sudden death. It has been demonstrated that leucine can reduce prolonged exercise-induced muscle damage and accelerate the recovery process. The aim of this study was to investigate the effects of prolonged strenuous endurance exercise on cardiovascular parameters and biomarkers of cardiac injury in trained adult male rats and assess the use of leucine as an auxiliary substance to prevent the likely cardiac adverse effects caused by strenuous exercise. Twenty-four male Wistar rats were randomly allocated to receive a balanced control diet (18% protein) or a leucine-rich diet (15% protein plus 3% leucine) for 6 weeks. The rats were submitted to 1 h of exercise, 5 days per week for 6 weeks. Three days after the training period, the rats were submitted to swimming exercise until exhaustion, and cardiac parameters were assessed. Exercising until exhaustion significantly increased cardiac biomarker levels, cytokines and glycogen content inhibited protein synthesis signalling and led to cardiac electrical disturbances. When combined with exercise, leucine supplementation led to greater increases in the aforementioned parameters and also a significant increase in blood pressure and protein degradation signalling. We report, for the first time, that leucine supplementation not only fails to prevent cardiac fatigue symptoms, but may also aggravate prolonged strenuous exercise-induced cardiovascular disturbances in trained rats. Furthermore, we find that exercising until exhaustion can cause cardiac electrical disturbances and damage cardiac myocytes.

Left Ventricular Function After Prolonged Exercise in Equine Endurance Athletes

BACKGROUND

Prolonged exercise in human athletes is associated with transient impairment of left ventricular (LV) function, known as cardiac fatigue. Cardiac effects of prolonged exercise in horses remain unknown.

OBJECTIVES

To investigate the effects of prolonged exercise on LV systolic and diastolic function in horses.

ANIMALS

Twenty-six horses competing in 120-160 km endurance rides.

METHODS

Cross-sectional field study. Echocardiography was performed before and after rides, and the following morning, and included two-dimensional echocardiography, anatomical M-mode, pulsed-wave tissue Doppler imaging, and two-dimensional speckle tracking. Correlation between echocardiographic variables and cardiac troponin I was evaluated.

RESULTS

Early diastolic myocardial velocities decreased significantly in longitudinal (baseline: -17.4 ± 2.4cm/s; end of ride: -15.8 ± 3.2cm/s (P = .013); morning after: -15.4 ± 3.0cm/s (P = .0033)) and radial directions (-32.8 ± 3.4cm/s; -28.1 ± 5.8cm/s (P < .001); -26.4 ± 5.5cm/s (P < .001)). Early diastolic strain rates decreased significantly in longitudinal (1.58 ± 0.27s(-1) ; 1.45 ± 0.26s(-1) (P = .036); 1.41 ± 0.25s(-1) (P = .013)) and circumferential directions (2.43 ± 0.29s(-1) ; 1.96 ± 0.46s(-1) (P < .001); 2.11 ± 0.32s(-1) (P < .001)). Systolic variables showed ambiguous results. No correlations with serum cardiac troponin I concentrations were evident.

CONCLUSIONS AND CLINICAL IMPORTANCE

Prolonged exercise in horses is associated with impaired LV diastolic function. Reduced ventricular filling persisted for 7-21 hours despite normalization of biochemical indicators of hydration status, indicating that the observed changes were not entirely related to altered preload conditions. The clinical relevance of cardiac fatigue in horses remains uncertain.

Are There Deleterious Cardiac Effects of Acute and Chronic Endurance Exercise?

Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including "myocardial" creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination.

Exercise-induced cardiac fatigue in low and normal birth weight young black adults

The objective of the study was to compare the change in diastolic function, E/A ratio, in response to prolonged exercise in low birth weight and normal birth weight individuals. Using a case-control study design, 23 students of the University of Zimbabwe College of Health Sciences who had neonatal clinic cards as proof of birth weight were recruited into the study. Measurements of diastolic function, E/A ratio, were obtained using an echocardiogram before and after 75 minutes of exercise. Among the cohort, seven had low birth weight - <2500 g, three female patients and four male patients - and 16 had normal birth weight - six female patients and 10 male patients). The mean age was 20.7±3.3 years. After prolonged exercise for 75 minutes of running on a treadmill, decreases in diastolic function, E/A ratio, were significantly greater in low birth weight than in normal birth weight individuals (0.48±0.27 versus 0.19±0.18 p<0.05, respectively). There was a significant association between low birth weight and exercise-induced cardiac fatigue (the χ2 test p<0.05, odds ratio 4.64, 95% confidence interval 1.19-18.1). We conclude that low birth weight is associated with exercise-induced diastolic dysfunction in young adults.

The impact of triathlon training and racing on athletes' general health

Although the sport of triathlon provides an opportunity to research the effect of multi-disciplinary exercise on health across the lifespan, much remains to be done. The literature has failed to consistently or adequately report subject age group, sex, ability level, and/or event-distance specialization. The demands of training and racing are relatively unquantified. Multiple definitions and reporting methods for injury and illness have been implemented. In general, risk factors for maladaptation have not been well-described. The data thus far collected indicate that the sport of triathlon is relatively safe for the well-prepared, well-supplied athlete. Most injuries 'causing cessation or reduction of training or seeking of medical aid' are not serious. However, as the extent to which they recur may be high and is undocumented, injury outcome is unclear. The sudden death rate for competition is 1.5 (0.9-2.5) [mostly swim-related] occurrences for every 100,000 participations. The sudden death rate is unknown for training, although stroke risk may be increased, in the long-term, in genetically susceptible athletes. During heavy training and up to 5 days post-competition, host protection against pathogens may also be compromised. The incidence of illness seems low, but its outcome is unclear. More prospective investigation of the immunological, oxidative stress-related and cardiovascular effects of triathlon training and competition is warranted. Training diaries may prove to be a promising method of monitoring negative adaptation and its potential risk factors. More longitudinal, medical-tent-based studies of the aetiology and treatment demands of race-related injury and illness are needed.

Influence of repeated bouts of table tennis training on cardiac biomarkers in children

It is documented that exercise can increase serum cardiac troponins in adults and adolescents; however, there is a lack of related studies concerning the release of cardiac troponins in children. This study investigated the influence of table tennis training on cardiac biomarkers in children. Twenty-eight male children performed six 10-min forehand exercise sessions with 5-min recovery intervals. Serum cardiac troponin T (cTnT) and I (cTnI), and creatinine kinase isoenzyme MB (CK-MB) were assessed before exercise, immediately after the last 10 min of exercise (PEI), 4 h post-exercise (PE4), 24 h post-exercise (PE24), and 48 h post-exercise (PE48). Cardiac function was measured using an ultrasound system (GE Vivid7 Dimension) at rest state. Serum cTnT, cTnI, and CK-MB were significantly elevated from the PEI sample point, and returned to baseline at the PE48 sample point in children. Serum cTnT in four (14.29%), nine (32.14%), and two (7.14%) subjects at the PEI, PE4, and PE24 sample points, respectively, exceeded the cutoff for myocardial injury. At the PE4 sample point, cTnT in five subjects (17.86%) exceeded the cutoff for acute myocardial infarction. Serum cTnI in two (14.29%), seven (25%), and two (7.14 %) subjects at the PEI, PE4, and PE24 timepoints, respectively, exceeded the cutoff for myocardial injury. cTnI in two subjects (7.14%) exceeded the cutoff for acute myocardial infarction at the PE4 timepoint in children. Repeated bouts of table tennis forehand training can significantly increase the release of serum cardiac troponins in some children.

Exercise-induced cardiac injury: evidence from novel imaging techniques and highly sensitive cardiac troponin assays

Prolonged endurance exercise in humans has been associated with an acute impairment in diastolic and systolic cardiac function and the release of cardiac troponin. In this chapter, we review recent evidence from studies using novel echocardiographic parameters and highly sensitive cardiac troponin assays. We demonstrate that the mechanics of left and right ventricular functions are acutely impaired after completion of prolonged exercise and that this reduction in function is likely multifactorial in etiology. However, we highlight that exercise-induced cardiac troponin release is not a marker of exercise-induced pathology but likely a physiologic response to exercise. Finally, we discuss the potential link between prolonged exercise and the increased incidence of cardiac pathology in veteran athletes.

Exercise and melatonin in humans: reciprocal benefits

The aim of this review is to update the reader as to the association between physical exercise and melatonin, and to clarify how the melatonin rhythm may be affected by different types of exercise. Exercise may act as a zeitgeber, although the effects of exercise on the human circadian system are only now being explored. Depending on the time of the day, on the intensity of light, and on the proximity of the exercise to the onset or decline of the circadian production of melatonin, the consequence of exercise on the melatonin rhythm varies. Moreover, especially strenuous exercise per se induces an increased oxidative stress that in turn may affect melatonin levels in the peripheral circulation because indole is rapidly used to combat free radical damage. On the other hand, melatonin also may influence physical performance, and thus, there are mutually interactions between exercise and melatonin production which may be beneficial.

Cardiac function following prolonged exercise: influence of age

This study sought to determine the influence of age on the left ventricular (LV) response to prolonged exercise (PE; 150 min). LV systolic and diastolic performance was assessed using echocardiography (ECHO) before (pre) and 60 min following (post) exercise performed at 80% maximal aerobic power in young (28 ± 4.5 years; n = 18; mean ± SD) and middle-aged (52 ± 3.9 years; n = 18) participants. LV performance was assessed using two-dimensional ECHO, including speckle-tracking imaging, to determine LV strain (LV S) and LV S rate (LV SR), in addition to Doppler measures of diastolic function. We observed a postexercise elevation in LV S (young: −19.5 ± 2.1% vs. −21.6 ± 2.1%; middle-aged: −19.9 ± 2.3% vs. −20.8 ± 2.1%; P < 0.05) and LV SR (young: −1.19 ± 0.1 vs. −1.37 ± 0.2; middle-aged: −1.20 ± 0.2 vs. −1.38 ± 0.2; P < 0.05) during recovery in both groups. Diastolic function was reduced during recovery, including the LV SR ratio of early-to-late atrial diastolic filling (SRe/a), in young (2.35 ± 0.7 vs. 1.89 ± 0.5; P < 0.01) and middle-aged (1.51 ± 0.5 vs. 1.05 ± 0.2; P < 0.01) participants, as were conventional indices including the E/A ratio. Dobutamine stress ECHO revealed a postexercise depression in LV S in response to increasing dobutamine dose, which was similar in both young (pre-exercise dobutamine 0 vs. 20 μg·kg−1·min−1: −19.5 ± 2.1 vs. −27.2 ± 2.2%; postexercise dobutamine 0 vs. 20 μg·kg−1·min−1: −21.6 ± 2.1 vs. −23.7 ± 2.2%; P < 0.05) and middle-aged participants (pre: −19.9 ± 2.3 vs. −25.3 ± 2.7%; post: −20.8 ± 2.1 vs. −23.5 ± 2.7; P < 0.05). This was despite higher noradrenaline concentrations immediately postexercise in the middle-aged participants compared with young (4.26 ± 2.7 nmol/L vs. 3.00 ± 1.4 nmol/L; P = 0.12). These data indicate that LV dysfunction is observed following PE and that advancing age does not increase the magnitude of this response.

The Athlete's Heart vs. the Failing Heart: Can Signaling Explain the Two Distinct Outcomes?

Cardiac remodeling is typically associated with disease and can lead to heart failure. In contrast, remodeling that occurs in the athlete's heart is considered an adaptive physiological response. This review provides an overview of signaling mechanisms responsible for inducing left ventricular hypertrophy in the athlete's heart and in settings of pathological hypertrophy and heart failure.

Heart sphingolipids in health and disease

In recent years, the role of sphingolipids in physiology and pathophysiology of the heart attracted much attention. Ceramide was found to be involved in the pathogenesis of cardiac dysfunction in animal models of ischemia/reperfusion injury, Type 2 diabetes and lipotoxic cardiomyopathy. On the other hand, another member of this lipid family, namely sphingosine-1-phosphate, has been shown to possess potent cardioprotective properties. This chapter provides a review of the role of ceramide and other bioactive sphingolipids in physiology and pathophysiology of the heart. We describe the role of PPARs and exercise in regulation of myocardial sphingolipid metabolism. We also summarize the present state of knowledge on the involvement of ceramide and sphingosine-1-phosphate in the development and prevention of ischemia/reperfusion injury of the heart. In the last section of this chapter we discuss the evidence for a role of ceramide in myocardial lipotoxicity.

Impaired left and right ventricular function following prolonged exercise in young athletes: influence of exercise intensity and responses to dobutamine stress

We examined the effect of intensity during prolonged exercise (PE) on left (LV) and right ventricular (RV) function. Subjects included 18 individuals (mean ± SE: age = 28.1 ± 1.1 yr, maximal aerobic power = 55.1 ± 1.6 ml · kg−1 · min−1), who performed 150 min of exercise at 60 and 80% maximal aerobic power on two separate occasions. Transthoracic echocardiography assessed systolic and diastolic performance, and blood sampling assessed hydration status and noradrenaline levels before (pre), during (15 and 150 min), and 60 min following (post) PE. β-Adrenergic sensitivity pre- and post-PE was assessed by dobutamine stress. High-intensity PE (15 vs. 150 min) induced reductions in LV ejection fraction (69.3 ± 1.3 vs. 63.5 ± 1.3%, P = 0.000), LV strain (−23.5 ± 0.6 vs. −22.3 ± 0.6%, P = 0.034), and RV strain (−26.3 ± 0.6 vs. −23.0 ± 0.6%, P < 0.01). Both exercise intensities induced diastolic reductions (pre vs. post) in the ratio of septal early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (2.15 ± 0.15 vs. 1.62 ± 0.09; 2.21 ± 0.15 vs. 1.48 ± 0.10), ratio of lateral early wave of annular tissue velocities to late/atrial wave of annular tissue velocities (3.84 ± 0.42 vs. 2.49 ± 0.20; 3.56 ± 0.32 vs. 2.08 ± 0.18), ratio of early to late LV strain rate (2.42, ± 0.16 vs. 1.97 ± 0.13; 2.30 ± 0.15 vs. 1.81 ± 0.11), and ratio of early to late RV strain rate (2.03 ± 0.17 vs. 1.51 ± 0.09; 2.16 ± 0.16 vs. 1.44 ± 0.11) ( P < 0.001). Evidence of β-adrenergic sensitivity was supported by a decreased strain, strain rate, ejection fraction, and systolic pressure-volume ratio response to dobutamine ( P < 0.05) with elevated noradrenaline ( P < 0.01). PE-induced reductions in LV and RV systolic function were related to exercise intensity and β-adrenergic desensitization. The clinical significance of exercise-induced cardiac fatigue warrants further research.

Melatonin reduces cardiac inflammatory injury induced by acute exercise

Cardiac muscle tissue, when stimulated by acute exercise, presents increased signs of cell damage. This study was designed to investigate whether overexpression of inflammatory mediators induced in the heart by acute exercise could be prevented by melatonin and whether the protective effect of melatonin was related with inhibition of nuclear factor kappa B (NF-kappaB) activation. Male Wistar rats received melatonin i.p. at a dose of 1.0 mg/kg body weight 3 min before being exercised for 60 min on a treadmill at a speed of 25 m/min and a 10% slope. Exercise was associated with a significant increase in myeloperoxidase activity and in TNF-alpha, IL-1 and IL-6 mRNA levels. Both mRNA level and protein concentrations of intercellular adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2 were also significantly elevated. A significant activation of nuclear factor kappa B (NF-kappaB) was observed in exercised rats. These effects were totally or partially prevented by melatonin administration. Data obtained indicate that melatonin protects against heart damage caused by acute exercise. Impaired production of noxious mediators involved in the inflammatory process and down-regulation of the NF-kappaB signal transduction pathway appear to contribute to the beneficial effects of melatonin.

Effect of exercise duration on ceramide metabolism in the rat heart

AIM

We aimed at gaining more insight into the mechanisms underlying exercise-induced alterations in myocardial ceramide (CER) content by employing physical activity of various durations and examining all key pathways of CER metabolism.

METHODS

The experiments were carried out on male Wistar rats divided into four groups (n = 6 in each case): control, exercised for 30 and 90 min and until exhaustion on the electrically driven treadmill moving with a speed of 1200 m h(-1) and set at +10 degrees incline. The animals were anaesthetized and samples of the heart's left ventricle were excised.

RESULTS

Thirty-minute exercise decreased the level of CER in the heart by 15%. However, after 90 min of running it returned to the baseline and at the point of exhaustion it exceeded that of the control animals by 26%. The initial reduction in the content of CER was probably a result of its augmented degradation, as a concomitant elevation in the activity of acid ceramidase and the level of sphingosine was observed. The transition from reduction in CER content after 30 min of exercise to its accumulation at the point of exhaustion was a consequence of gradual reduction in the activity of acid ceramidase and simultaneous increase in the rate of de novo CER synthesis, as evidenced by progressive activation of serine palmitoyltransferase and accumulation of sphinganine.

CONCLUSION

We conclude that the effect of physical effort on myocardial CER content and metabolism depends to a large extent on exercise duration.

Time-course of changes in cardiac function during recovery after acute exercise

Exercise-induced cardiac dysfunction (EICD) has been observed immediately following exhaustive exercise in trained individuals, but limited and conflicting data are available regarding EICD in a previously untrained population days after an exhaustive exercise bout. The purpose of this study was to examine the effects of a single bout of acute exercise on cardiac function during the 72 h after exercise and identify potential contributing mechanisms. After completing an acute exercise bout on a motorized treadmill (25 m/min, 5% grade, 60 min), rats were sacrificed immediately, 24 h, 48 h, or 72 h after the exercise bout. At the scheduled time of sacrifice, hearts were isolated and perfused for determination of ex vivo cardiac function, and examined for malondialdehyde (MDA), a lipid peroxidation index, and antioxidant potential (AOP). During the 48 h post exercise, left ventricular developed pressure decreased by 30%, dP/dtmax declined by 37%, and dP/dtmin showed a 34% decrease (p < 0.05). By 72 h, cardiac function had returned to control levels. MDA was increased immediately after the exercise bout and at the 24 and 48 h intervals (p < 0.05). Conversely, AOP progressively decreased at the 24 and 48 h intervals. As with cardiac function, MDA and AOP had returned to control levels by 72 h post-exercise. These data indicate that a single bout of prolonged, moderately intense exercise performed by previously sedentary rats impaired cardiac function for up to 48 h. This decrement in cardiac function was associated with increased lipid peroxidation and decreased antioxidant potential.

Effect of Preload Augmentation on Pulsed Wave and Tissue Doppler Echocardiographic Indices of Diastolic Function After a Marathon

BACKGROUND

The mechanisms underlying alterations in left ventricular diastolic function after a marathon are unknown and may be a consequence of a reduced preload.

OBJECTIVE

We sought to assess the effect of preload augmentation through passive leg elevation (PLE) on echocardiographic indices of diastolic function after a marathon.

METHODS

Fourteen trained participants (13 male) were echocardiographically assessed before and after a marathon in the supine position and during PLE. Diastolic function was measured via conventional Doppler, color M-mode, and tissue Doppler echocardiography. Early and late transmitral filling velocities (E and A, respectively), flow propagation velocity of early filling, and basal early and late left ventricular wall velocities (E' and A', respectively) were obtained.

RESULTS

The E/A ratio, flow propagation velocity of early filling, and the E'/A' ratio decreased by 31%, 24%, and 32%, respectively (P < .05), after marathon running. Postrace PLE returned E to baseline and increased E/A compared with postrace supine (P < .05). However, E/A remained depressed compared with baseline as a result of the persistent elevation in A. Postrace PLE caused Vp to return to baseline; mean E' also increased (9%, P < .05), but did not return to resting levels. Mean A' was unaffected by postrace PLE, therefore, E'/A' was unchanged postrace despite PLE.

CONCLUSION

Postexercise alterations in Doppler indices of diastolic function can be partially explained by a reduction in preload. However, data from tissue Doppler echocardiography indicate that there is an intrinsic impairment in myocardial relaxation after marathon running.

Non-invasive determination of stroke volume and cardiac output after high intensity playing exercise in elite female soccer players

BACKGROUND

Stroke volume (SV) and heart rate (HR), determining cardiac output (CO), are crucial hemodynamic parameters determining training adoptions to endurance training. In soccer, aerobic power as well as intermittent exercise performance varies significantly among level of competition as well as playing position. In this study cohort study we thought to determine the hemodynamic changes following a standardized soccer-specific exercise in female soccer players at the soccer field using a portable non-invasive hemodynamic monitoring tool.

METHODS

A non-invasive, portable continuous wave (CW) Doppler-based ultrasound system (USCOM, Sydney, Australia) was used to assess HR, SV, CO, and cardiac index (CI) using a suprasternal approach after a soccer specific exercise (5-vs-2-gameplay over 5 min) in an elite female soccer team of the German Fussball Bundesliga (15 females, 22.3+/-3.6 years).

RESULTS

30 s after the peak exercise the mean HR increased significantly (121+/-26 /min vs 56+/-11 /min, p<0.05), while SV did not change significantly (75+/-25 ml vs. 80+/-13 ml, n.s.). CO increased significantly (9.2+/-4.1 l/min vs. 4.5+/-1.1 l/min) as did CI (5.3+/-2.1 l/min/m(2) vs. 2.6+/-0.6 l/min/m(2), p<0.05).

CONCLUSION

Elite female soccer players increase cardiac output after 5-vs-2-gameplay on average to 10 l/min, in single cases up to 18 l/min 30 s after peak exercise. Therefore significant peak hemodynamic demands are encountered in soccer game play. The increase of cardiac output is by far more achieved by an increase of the heart rate than by stroke volume changes in most of the female soccer players. On field hemodynamic exercise testing is feasible using the USCOM in elite soccer.

Preload maintenance and the left ventricular response to prolonged exercise in men

This study examined whether left ventricular function was reduced during 3 h of semi-recumbent ergometer cycling at 70% of maximal oxygen uptake while preload to the heart was maintained via saline infusion. Indices of left ventricular systolic function (end-systolic blood pressure-volume relationship, SBP/ESV) and diastolic filling (ratio of early to late peak filling velocities into the left ventricle, E:A) were calculated during recovery and compared with baseline resting data. During exercise in seven healthy, trained male subjects, an arterial catheter allowed continuous assessment of arterial pressure, stroke volume (SV), cardiac output ( ) and an index of contractility (dP/dt(max)). A venous catheter assessed that central venous pressure (CVP) was maintained throughout rest, exercise and 10 min into recovery. Both systolic blood pressure and heart rate (HR) increased with the onset of exercise (from 132 +/- 5 to 185 +/- 19 mmHg and from 66 +/- 9 to 135 +/- 23 beats min(-1); increases from rest to the end of the first 5 min of exercise in SBP and HR, respectively) but systolic blood pressure did not change from 30 to 180 min of exercise ( approximately 150 mmHg), while heart rate only increased by 8 +/- 9 beats min(-1) (means +/- s.d.; P > 0.05). The attenuated increase in HR compared with other studies suggests that the maintained CVP ( approximately 5 mmHg) helped to prevent cardiovascular drift in this protocol. Stroke volume, and dP/dt(max) were all increased with the onset of exercise (from 85 +/- 8 to 120 +/- 18 ml, from 5.4 +/- 1.3 to 16.5 +/- 3.3 l min(-1) and from 14.4 +/- 4 to 28 +/- 8 mmHg s(-1); values from rest to the end of the first 5 min of exercise for SV, and dP/dt(max), respectively) and were maintained during exercise. There was no difference in the SBP/ESV ratio from pre- to postexercise. Conversely, E:A was reduced from 2.0 +/- 0.4 to 1.6 +/- 0.5 postexercise (P < 0.05), returning to normal values at 24 h postexercise. This change in diastolic filling could not be fully explained (r(2) = 0.39) by an increased heart rate and, with CVP unchanged, it is likely to represent some depression of intrinsic relaxation properties of left ventricular myocytes. Three hours of semi-supine cycling resulted in no evidence of a depression in left ventricular systolic function, while left ventricular diastolic function declined postexercise.

Treat the patient not the blood test: the implications of an increase in cardiac troponin after prolonged endurance exercise

Collapse after prolonged endurance exercise is common and usually benign. This case study reports a triathlete who suffered a vaso-vagal associated collapsed after exercise. Misdiagnosis of myocardial injury in the presence of elevated cardiac troponins and ECG anomalies led to inappropriate management and highlights the difficulty in treating the collapsed athlete following arduous exercise.

Impact of Repeated Prolonged Exercise Bouts on Cardiac Function and Biomarkers

PURPOSE

The present study examined the impact of repeated bouts of prolonged (< 60 min) exercise on left ventricular function and cardiac biomarkers.

METHODS

Ten athletes completed a 15.3-mile hill run on three consecutive days and were assessed before, immediately after, 1 h after, and 20 h after each bout. Six of the athletes completed a fourth bout. Left ventricular (LV) function was examined echocardiographically using two-dimensional M-mode, Doppler, and flow propagation velocity (Vp). Venous blood samples were analyzed for cardiac biomarkers including cardiac troponin T (cTnT).

RESULTS

Ejection fraction (EF) significantly decreased (P = 0.027) after the third exercise bout compared with baseline (mean +/- SD: 56.3 +/- 4.4 vs 51.3 +/- 5.9%), accompanied by a nonsignificant decrease in systolic blood pressure/end systolic volume (SBP/ESV) ratio. A sustained depression in systolic function 20 h after bout 3 also persisted in the subset who completed a fourth bout, yet this did not reach clinical levels. Significant (P < 0.01) reductions in early to late diastolic filling (E:A) ratio pre-to post-bout 1 (mean +/- SD: 1.9 +/- 0.5 vs 1.4 +/- 0.3) and pre- to post-bout 3(2.0 +/- 0.5 vs 1.3 +/- 0.4) normalized after each 20-h recovery period. A similar pattern of change was observed in Vp. Cardiac troponin T was elevated in four individuals 1 h after bout 1 (range: 0.013-0.125 microg.L(-1)) but was undetectable thereafter except in one athlete.

CONCLUSION

Repeated bouts of prolonged exercise induce short-term reductions in diastolic filling and a cumulative decrease in systolic function, yet these alterations seem to have minimal clinical or functional impact. Elevated cTnT after the initial bout, but not thereafter, may represent an adaptive response to prolonged exercise.

Sex differences in left ventricular function and beta-receptor responsiveness following prolonged strenuous exercise

Sex differences in neuroendocrine and metabolic responses to prolonged strenuous exercise (PSE) have been well documented. The aim of this investigation was to examine sex differences in left ventricular function and cardiac beta-receptor responsiveness following a single bout of PSE. Nine male and eight female triathletes were examined during three separate sessions: before, immediately after, and 24 h following a half-ironman triathlon using dobutamine stress echocardiography. Steady-state graded infusions of dobutamine were used to assess beta-receptor responsiveness. Slopes calculated from linear regressions between dobutamine doses and changes in heart rate and contractility for each participant were used as an index of beta-receptor responsiveness. Despite no change in preload, fractional area change decreased from baseline after the race in both men and women, with a greater decrease in men [men: 54.1% (SD 2.1) to 50.7% (SD 3.4) vs. women: 55.4% (SD 2.7) to 53.3% (SD 2.5); P < 0.05]. The amount of dobutamine necessary to increase heart rate by 25 beats/min [men: 29.6 microg x kg(-1) x min(-1) (SD 6.6) to 42.7 microg x kg(-1) x min(-1) (SD 12.9) vs. women: 23.5 microg x kg(-1) x min(-1) (SD 4.0) to 30.0 microg x kg(-1) x min(-1) (SD 7.8); P < 0.05] and contractility by 10 mmHg/cm2 [men: 20.9 microg x kg(-1) x min(-1) (SD 5.1) to 37.0 microg x kg(-1) x min(-1) (SD 11.5) vs. women: 22.6 microg x kg(-1) x min(-1) (SD 6.4) to 30.7 microg x kg(-1) x min(-1) (SD 7.2); P < 0.05] was greater in both men and women postrace. However, the amount of dobutamine required to induce these changes was greater in men, reflecting larger beta-receptor alterations in male triathletes following PSE relative to women. These data suggest that following an acute bout of PSE, male triathletes demonstrate an attenuated chronotropic and inotropic response to beta-adrenergic stimulation compared with female triathletes.

Cardiac and vascular adaptations to exercise

PURPOSE OF REVIEW

To briefly review some recent studies of cardiac and vascular adaptation to acute exercise and exercise training.

RECENT FINDINGS

Recent studies have suggested that prolonged strenuous bouts of exercise may be associated with transient impairment in systolic and diastolic function, referred to as 'cardiac fatigue'. Furthermore, some studies have reported increased circulating concentrations of cardiac troponins and brain natriuretic peptide following prolonged endurance exercise, suggestive of possible myocyte damage or impairment. Meanwhile, emerging studies of the effects of exercise training on diastolic function are somewhat conflicting; the discrepancies may relate to variability in study designs, indices selected to represent diastolic function or timing of measurements around training cycles. Finally, recent studies of vascular structure and function confirm established evidence for remodelling of large and small arteries and improvement in vascular function with exercise training.

SUMMARY

Emerging evidence suggests that prolonged strenuous exercise may be associated with 'cardiac fatigue' or 'cardiac damage', although the clinical implications remain obscure. Vascular adaptations to training improve vasomotor function and induce arterial enlargement, favouring decreased atherothrombotic risk.

Beta-adrenergic receptor desensitization in man: insight into post-exercise attenuation of cardiac function

Desensitization of the beta-adrenoreceptors (beta-AR) may contribute to a post-exercise reduction in left ventricular (LV) function. However, attenuation of the chronotropic and inotropic responses to a beta-AR agonist may depend upon alterations in parasympathetic tone. Furthermore, changes in cardiac output and LV diastolic function in response to a beta-AR agonist, pre- to post-prolonged exercise, remain unclear. Seven trained males (mean+/-s.d., age 27+/-6 years) performed 4 h of ergometer rowing. Peak heart rate (HR) and LV systolic and diastolic functional responses to incremental isoproterenol (isoprenaline) infusion (2, 4 and 6 microg kg min-1) were assessed after vagal blockade (glycopyrrolate, 1.2 mg). LV systolic function was assessed by the pressure/volume ratio (systolic blood pressure/end systolic volume) and , whilst diastolic function was evaluated as peak early and late transmitral filling velocities. Following exercise, the pressure/volume ratio decreased by 25% (P<0.05), whereas was unchanged (P>0.05). The early/late filling ratio was reduced by 36% after exercise, due to an elevation in late LV filling (P<0.01). The increase in HR response to isoproterenol infusion was blunted post-exercise at both 4 and 6 microg kg min-1 (127+/-7 and 132+/-6 beats min-1) compared with pre-exercise (138+/-8 and 141+/-12 beats min-1, P<0.05). Additionally, the pressure/volume ratio and were blunted post-exercise in response to isoproterenol (P<0.05). In contrast, diastolic function was similar before and after exercise during isoproterenol infusion (P>0.05). Desensitization of the beta-AR contributes to an attenuated left ventricular systolic but not diastolic function following prolonged exercise.