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

Exercise-Induced Cardiac Troponin I Elevation Is Associated With Regional Alterations in Left Ventricular Strain in High-Troponin Responders

BACKGROUND

The implications of exercise-induced cardiac troponin elevation in healthy individuals are unclear. This study aimed to determine if individuals with a high exercise-induced cardiac troponin I (cTnI) response have alterations in myocardial function following high-intensity endurance exercise compared with normal-cTnI responders.

METHODS AND RESULTS

Study individuals were recruited from previous participants in a 91-km mountain bike cycling race (the North Sea Race) and were classified as high- (n=34) or normal-cTnI responders (n=25) based on maximal cTnI values after the recruitment race. The present study exposed all participants to 2 prolonged high-intensity exercises: a combined lactate threshold and cardiopulmonary exercise test and repeated participation in the North Sea Race. Echocardiography was performed before, immediately after, and 24 hours following exercise. All study individuals (n=59) had normal coronary arteries, and were aged 51±10 years; 46 (74%) were men. There were no differences in baseline characteristics between the high- and normal-cTnI responders. Maximal cTnI levels 3 hours after exercise were significantly higher in the high- compared with normal-cTnI group (P<0.001-0.027). Following exercise, there were no differences in global ventricular function between the 2 groups. In contrast, high-cTnI responders had significantly lower regional strain in the anteroseptal segments following exercise, with more profound changes after the race.

CONCLUSIONS

High-cTnI responders had lower anteroseptal segmental strain shortly after exercise than normal-cTnI responders. However, there were no permanent alterations in myocardial strain, indicating no short- or long-term adverse consequences of these exercise-induced alterations in myocardial function.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02166216.

Cardiac Troponin Release after Exercise in Healthy Young Athletes: A Systematic Review

Cardiac troponin (cTn) is a recognized marker used to assess damage to the heart muscle. Actual research has indicated that the levels of cTn increase after doing exercise in individuals who are in good health, and this is believed to be a result of a normal cellular process rather than a pathological one. The main goal of this study was to investigate the evidence of a postexercise release of cTn in child and adolescent athletes (6-17.9 years old) of different ages, sex, and sports disciplines. The Web of Science, MEDLINE, and Scopus databases were used to conduct the research up to March 2023. Three hundred and twenty-eight records were identified from the databases, however, only twenty-three studies were included in the review after being screened and quality-assessed by two independent authors. The gender, age of the participants, maturational status, and training level of the participants, the timing of sample collection, the exercise modality, and the number of participants with values above the cut-off reference were the data analyzed. Males, older young people, and individual sports seemed to have higher levels of serum cTn after practice exercise. Different methodologies, analyzers, and cut-off reference values make it difficult to compare the data among studies.

Myocardial inefficiency is an early indicator of exercise-induced myocardial fatigue

Background

The effect of prolonged, high-intensity endurance exercise on myocardial function is unclear. This study aimed to determine the left ventricular (LV) response to increased exercise duration and intensity using novel echocardiographic tools to assess myocardial work and fatigue.

Materials and methods

LV function was assessed by echocardiography before, immediately, and 24 h after a cardiopulmonary exercise test (CPET) and a 91-km mountain bike leisure race. Cardiac Troponin I (cTnI) was used to assess myocyte stress.

Results

59 healthy recreational athletes, 52 (43-59) years of age, 73% males, were included. The race was longer and of higher intensity generating higher cTnI levels compared with the CPET (p < 0.0001): Race/CPET: exercise duration: 230 (210, 245)/43 (40, 45) minutes, mean heart rate: 154 ± 10/132 ± 12 bpm, max cTnI: 77 (37, 128)/12 (7, 23) ng/L. Stroke volume and cardiac output were higher after the race than CPET (p < 0.005). The two exercises did not differ in post-exercise changes in LV ejection fraction (LVEF) or global longitudinal strain (GLS). There was an increase in global wasted work (p = 0.001) following the race and a persistent reduction in global constructive work 24 h after exercise (p = 0.003).

Conclusion

Increased exercise intensity and duration were associated with increased myocardial wasted work post-exercise, without alterations in LVEF and GLS from baseline values. These findings suggest that markers of myocardial inefficiency may precede reduction in global LV function as markers of myocardial fatigue.

Role of cardiac magnetic resonance imaging in troponinemia syndromes

Cardiac magnetic resonance imaging (MRI) is an evolving technology, proving to be a highly accurate tool for quantitative assessment. Most recently, it has been increasingly used in the diagnostic and prognostic evaluation of conditions involving an elevation in troponin or troponinemia. Although an elevation in troponin is a nonspecific marker of myocardial tissue damage, it is a frequently ordered investigation leaving many patients without a specific diagnosis. Fortunately, the advent of newer cardiac MRI protocols can provide additional information. In this review, we discuss several conditions associated with an elevation in troponin such as myocardial infarction, myocarditis, Takotsubo cardiomyopathy, coronavirus disease 2019 related cardiac dysfunction and athlete’s heart syndrome.

Racing-associated fatalities in Norwegian and Swedish harness racehorses: Incidence rates, risk factors, and principal postmortem findings

BACKGROUND

There are no reports on the number of fatalities or causes of death in the Norwegian and Swedish harness racehorses.

OBJECTIVES

The incidence rates (IRs), risk factors, and postmortem findings in horses that died or were euthanized associated with racing between 2014 and 2019 were investigated.

ANIMALS

Thirty-eight Standardbreds and 10 Norwegian-Swedish Coldblooded Trotters died or were euthanized associated with racing. A total of 816 085 race-starts were recorded.

METHODS

Incidence rates were calculated for both countries and horse breeds. Risk factors for sudden death were identified using a case-control logistic model. Postmortem examinations were performed in 43 horses.

RESULTS

The overall fatality IR was 0.059/1000 race-starts. Traumatic injuries accounted for 14.5%, while sudden death for 85.5% of fatalities. Only minor differences between countries and breeds were recorded. The number of starts within the last 30 days increased the risk of sudden death (5 starts odds ratio (OR) 228.80, confidence interval (CI) 10.9-4793). An opposite non-linear effect was observed in number of starts the last 180 days (>10 starts OR 0.12, CI 0.02-0.68). Seven horses were euthanized because of catastrophic injury. Acute circulatory collapse because of suspected cardiac or pulmonary failure or both was recorded in 30 horses, while major hemorrhage after vessel rupture was the primary cause of death in 10 cases. One horse collapsed and died but was not submitted for autopsy.

CONCLUSIONS AND CLINICAL IMPORTANCE

Comparatively low rates of catastrophic orthopedic fatalities were reported, while causes and IR of sudden death were similar to previous studies.

Sudden cardiac death in sports: could we save Pheidippides?

Hereditary diseases under the age of 35 are the most common underlying heart disease, leading to sudden cardiac death (SCD) in competitive sports, while in older people, atherosclerotic coronary artery disease (CAD) is the main cause. The following preventive measures are recommended: (a) The pre-participation cardiovascular screening, (b) the genetic testing, (c) the use of implantable cardioverter-defibrillator (ICD), (d) the prohibition of doping in sports, (e) the prevention of 'exercise-induced' cardiac complications, (f) the reduction of high-risk factors for CAD, and (g) the use of cardiopulmonary resuscitation. The cost-effectiveness of the electrocardiograms in the pre-participation screening programs remains questionable. Genetic testing is recommended in borderline cases and positive family history. Athletes with ICD can, under certain conditions, participate in competitive sports. Excessive endurance exercise appears to harm the endothelium, promotes inflammatory processes and leads to fibrosis in the myocardium, and calcium deposition in the coronary vessels. Cardiac arrest may be reversed if cardiopulmonary resuscitation is performed and a defibrillator is immediately used. Thus, equipping all fields with automatic external defibrillators are recommended.

Exercise-Induced Cardiovascular Adaptations and Approach to Exercise and Cardiovascular Disease: JACC State-of-the-Art Review

The role of the sports cardiologist has evolved into an essential component of the medical care of athletes. In addition to the improvement in health outcomes caused by reductions in cardiovascular risk, exercise results in adaptations in cardiovascular structure and function, termed exercise-induced cardiac remodeling. As diagnostic modalities have evolved over the last century, we have learned much about the healthy athletic adaptation that occurs with exercise. Sports cardiologists care for those with known or previously unknown cardiovascular conditions, distinguish findings on testing as physiological adaptation or pathological changes, and provide evidence-based and "best judgment" assessment of the risks of sports participation. We review the effects of exercise on the heart, the approach to common clinical scenarios in sports cardiology, and the importance of a patient/athlete-centered, shared decision-making approach in the care provided to athletes.

The impact of an ultra-trail on the dynamic of cardiac, inflammatory, renal and oxidative stress biological markers correlated with electrocardiogram and echocardiogram

The aim of this study was to describe the effects of a 64.2 km ultra-trail on the biomarkers of muscle damage, inflammation and oxidative stress, and compare the results observed with an ECG and an echocardiogram, both performed before and after the race.Thirty-three ultra-trail volunteers (45.8 ± 8.7 years old) were enrolled in our study. Three blood tests were drawn from each runner, one just before (TPRE), one just after (TPOST) and the last 3 h after the end of the race (TPOST3h).All the markers increased. The maximum concentrations observed were at TPOST3h and were significant (p < 0.001) for creatine kinase, creatine kinase isoform MB, high-sensitivity C-reactive protein, uric acid and for the ratio of reduced glutathione to oxidised glutathione. However, in the case of myoglobin, high-sensitive troponin T, N-terminal pro-brain natriuretic peptide, oxidised glutathione, myeloperoxidase, cystatin C and creatinine, the most significant increases were at TPOST (p < 0.001). Modifications were observed in the medical imaging using echocardiography such as reduction of left ventricule end-sytolic and diastolic volumes and left ventricular global longitudinal strain. ECG showed electrical criteria for left ventricular hypertrophy and incomplete right bundle branch block after the race.Endurance races cause significant physiological stress to the body that can be measured by the increase of different biomarkers. From a laboratory perspective, it is important to take into account the possible exercise performed previous to the testing to avoid a misinterpretation of the results. From a training perspective, due to these increases in biomarkers, it is recommended that runners wait at least 72 h after an ultra-trail before subsequent training. In addition a transient impairment of ventricular function due to dehydration were observed.

The Effects of Interval Training and Continuous Training on Cardiopulmonary Fitness and Exercise Tolerance of Patients with Heart Failure-A Systematic Review and Meta-Analysis

PURPOSE

To investigate the effects of interval training (IT) as compared with continuous training (CT) on cardiorespiratory fitness and exercise tolerance of patients with heart failure (HF), with the aim to provide reasonable exercise prescriptions for patients with HF.

METHODS

Through searching electronic databases, randomized controlled studies were collected. The included studies were evaluated for methodological quality using the Cochrane risk of bias assessment tool, and statistical analyses were carried out using Review Manager 5.3 and Stata MP 15.1 software.

RESULTS

A total of seventeen randomized controlled trials (i.e., studies) with 617 patients were included. The meta-analysis showed that IT can improve a patient's peak oxygen uptake (VO2peak) (MD = 2.08, 95% CI 1.16 to 2.99, p < 0.00001), left ventricular ejection fraction (LVEF) (MD =1.32, 95% CI 0.60 to 2.03, p = 0.0003), and 6-minute walk distance (6MWD) (MD = 25.67, 95% CI 12.87 to 38.47, p < 0.0001) as compared with CT. However, for respiratory exchange ratio (RER) (MD = 0.00, 95% CI -0.02 to 0.03, p = 0.81), CO2 ventilation equivalent slope (VE/VCO2 slope) (SMD = 0.04, 95% CI -0.23 to 0.31, p = 0.75), and resting heart rate (HRrest) (MD = 0.15, 95% CI -3.00 to 3.29, p = 0.93) there were no statistical significance.

CONCLUSIONS

The evidence shows that IT is better than CT for improving the cardiorespiratory fitness and exercise tolerance of patients with HF. Moreover, an intensity of 60-80% peak heart rate of IT is the optimal choice for patients. It is hoped that, in the future, more well-designed studies would further expand the meta-analysis results.

Cardiac perturbations after high-intensity exercise are attenuated in middle-aged compared with young endurance athletes: diminished stress or depleted stimuli?

Strenuous exercise elicits transient functional and biochemical cardiac imbalances. Yet, the extent to which these responses are altered owing to aging is unclear. Accordingly, echocardiograph-derived left ventricular (LV) and right ventricular (RV) global longitudinal strain (GLS) and high-sensitivity cardiac troponin I (hs-cTnI) were assessed before (pre) and after (post) a 60-min high-intensity cycling race intervention (CRIT₆₀) in 11 young (18-30 yr) and 11 middle-aged (40-65 yr) highly trained male cyclists, matched for cardiorespiratory fitness. LV and RV GLS were measured at rest and during a semirecumbent exercise challenge performed at the same intensity (young: 93 ± 10; middle-aged: 85 ± 11 W, P = 0.60) pre- and post-CRIT₆₀. Augmentation (change from rest-to-exercise challenge) of LV GLS (pre: -2.97 ± 0.65; post: -0.82 ± 0.48%, P = 0.02) and RV GLS (pre: -2.08 ± 1.28; post: 3.08 ± 2.02%, P = 0.01) was attenuated and completely abolished, in the young following CRIT₆₀, while augmentation of LV GLS (pre: -3.21 ± 0.41; post: -3.99 ± 0.55%, P = 0.22) and RV GLS (pre: -3.47 ± 1.44; post: -1.26 ± 1.00%, P = 0.27) was preserved in middle-aged following CRIT₆₀. While serum hs-cTnI concentration increased followingCRIT₆₀ in the young (pre: 7.3 ± 1.6; post: 17.7 ± 1.6 ng/L, P < 0.01) and middle-aged (pre: 4.5 ± 0.6; post: 10.7 ± 2.0 ng/L, P < 0.01), serum hs-cTnI concentration increased to a greater extent in the young than in the middle-aged following CRIT₆₀ (P < 0.01). These findings suggest that functional and biochemical cardiac perturbations induced by high-intensity exercise are attenuated in middle-aged relative to young individuals. Further study is warranted to determine whether acute exercise-induced cardiac perturbations alter the adaptive myocardial remodeling response.NEW & NOTEWORTHY High-intensity endurance exercise elicits acute cardiac imbalances that may be an important stimulus for adaptive cardiac remodeling. This study highlights that following a bout of high-intensity exercise that is typical of routine day-to-day cycling training, exercise-induced autonomic, biochemical, and functional cardiac imbalances are attenuated in middle-aged relative to young well-trained cyclists. These findings suggest that aging may alter exercise-induced stress stimulus response that initiates cardiac remodeling in athlete's heart.

Cardiac and renal biomarkers in recreational runners following a 21 km treadmill run

Background

Highly trained athletes running 42 km or more demonstrate elevated cardiac biomarkers, ventricular dysfunction, and decreased glomerular filtration rate (GFR). Whether similar changes occur in the much larger population of recreational runners following half‐marathon distance running is unclear.

Hypothesis

Recreational runners exhibit changes in myocardial and renal biomarkers, including ventricular strain, after a half‐marathon treadmill run.

Methods

10 recreational subjects (mean age 36.5 ± 6.5 years) ran 21 km on a treadmill (mean completion time 121.6 ± 16.1 minutes). Serum high‐sensitivity troponin T (hsTnT), amino‐terminal pro‐brain natriuretic peptide (NT‐proBNP), creatinine, and neutrophil gelatinase‐associated lipocalin (NGAL) were measured prior to, 1 hour post‐, and 24 hours post‐exercise. Pre‐ and post‐exercise echocardiograms were performed.

Results

All biomarkers increased 1 hour post‐exercise: hsTnT by 8.5 ± 8.5 pg/ml (P < .05), NT‐ProBNP by 26.2 ± 22.8 pg/ml (P < .05) and NGAL by 29.5 ± 37.7 ng/ml (P=NS). By 24 hours post‐run, these biomarkers declined toward baseline levels. Right ventricle (RV) free wall and left ventricle global longitudinal strain decreased by 5.5% and 1.8%, respectively (P < .001). Changes in NGAL correlated well with changes in serum creatinine (R = 0.79, P < .01) and GFR (R = −0.73, P < .05). Faster 21 km completion times, and a larger reduction in post‐exercise RV strain, were associated with higher NGAL levels: (R = −0.75, P = .01) and (R = 0.66, P < .05), respectively.

Conclusion

A 21 km run in recreational runners is associated with transient ventricular stunning and reversible changes in myocardial and renal biomarkers. Whether repeated bouts of similar activity contributes to chronic cardiac or kidney dysfunction deserves further evaluation.

Exercise-induced release of troponin

It is well established that regular physical activity reduces cardiovascular disease risk; however, numerous studies have demonstrated postexercise elevations in cardiac troponin (cTn), indicative of cardiac injury in apparently healthy individuals. The prevalence of these findings in different exercise settings and population groups, as well as potential underlying mechanisms and clinical significance of exercise-induced cTn release are not yet quite determined. The present review will discuss the cTn response to exercise in light of developing cTn assays and the correlation between postexercise cTn release and cardiac function. Additionally, recent data regarding the potential link between strenuous endurance exercise and its relationship with unfavorable cardiac effects in athletes, as well as the management of patients presenting at emergency care after sport events will be briefly reviewed.

Right Ventricular Diastolic Dysfunction after Marathon Run

It has been raised that marathon running may significantly impair cardiac performance. However, the post-race diastolic function has not been extensively analyzed. We aimed to assess whether the marathon run causes impairment of the cardiac diastole, which ventricle is mostly affected and whether the septal (IVS) function is altered. The study included 34 male amateur runners, in whom echocardiography was performed two weeks before, at the finish line and two weeks after the marathon. Biventricular diastolic function was assessed not only with conventional Doppler indices but also using the heart rate-adjusted isovolumetric relaxation time (IVRTc). After the run, IVRTc elongated dramatically at the right ventricular (RV) free wall, to a lesser extent at the IVS and remained unchanged at the left ventricular lateral wall. The post-run IVRTc_IVS correlated with IVRTc_RV (r = 0.38, p < 0.05), and IVRTc_RV was longer in subjects with IVS hypertrophy (88 vs. 51 ms; p < 0.05). Participants with measurable IVRT_RV at baseline (38% of runners) had longer post-race IVRTc_IVS (102 vs. 83 ms; p < 0.05). Marathon running influenced predominantly the RV diastolic function, and subjects with measurable IVRT_RV at baseline or those with IVS hypertrophy can experience greater post-race diastolic fatigue.

Influence of maturational status in the exercise-induced release of cardiac troponin T in healthy young swimmers

OBJECTIVES

To determine the influence of maturational status on the release of cardiac troponin T (cTnT) induced by a bout of 30min, high-intensity, continuous exercise.

DESIGN

Quasi-experimental, cross-sectional study.

METHODS

Seventy male, young, well trained swimmers (age range 7-18 years, training experience 1-11 years) were classified by maturational stages: Tanner stage I (n=14), II (n=15), III (n=15), IV (n=13), and V (n=13). Participants underwent a distance-trial of 30min continuous swimming, and cTnT was measured before, immediately after and 3h after exercise. Changes in cTnT over time were compared among groups, and associated with exercise load.

RESULTS

Basal cTnT was higher in Tanner-V (3.8-8.1ng/L) compared with I (1.5-5.5ng/L, p<0.001), II (1.5-4.5ng/L, p<0.001) and III (1.5-6.8ng/L, p=0.003), and in IV (1.5-6.3ng/L) compared with II (p=0.036). Maximal elevations of cTnT from baseline were notable (p<0.001) and comparable among maturational stages (p=0.078). The upper reference limit for myocardial injury was exceeded in 35.7% of the participants, without differences among groups (p=0.18). Baseline cTnT correlated with participant characteristics, and maximal cTnT elevations from baseline with exercise internal load (%HRpeak, r_s=0.34, p= 0.003; %HRmean, r_s=0.28, p=0.02).

CONCLUSIONS

Maturational status influences positively absolute pre- and post-exercise cTnT but not its elevation after a bout of 30min, high-intensity, continuous exercise.

Impact of training specificity on exercise-induced cardiac troponin elevation in professional athletes: A pilot study

BACKGROUND

Release of cardiac biomarkers is common after strenuous endurance exercise, but data on intermittent exercise are scarce. It has not been investigated whether cardiac troponin elevation is influenced depending on the type of exercise that an athlete is adapted to perform. We hypothesized that intermittent but not continuous exercise induces cardiac troponin elevation in professional athletes adapted to high-intensity intermittent exercise.

AIM

To examine how training specificity impacts high-sensitivity cardiac troponin T (hs-cTnT) release.

METHODS

Nine professional floorball players participated in the study, which comprised two different exercise tests: a continuous incremental cycle ergometer test and a Yo-Yo Intermittent Recovery 2 (Yo-Yo IR2) test. Serial assessment of hs-cTnT was performed after the cycle ergometer test and the Yo-Yo IR2 test (baseline, 0, 2, 6, and 24 h).

RESULTS

No hs-cTnT elevation above the myocardial damage cutoff (≥ 14 ng/L) was shown after the cycle ergometer test, whereas hs-cTnT levels rose over the cutoff in three of nine participants after the Yo-Yo IR2 test. The hs-cTnT levels peaked at 6 h after both tests, but were significantly higher after the Yo-Yo IR2 test compared to the cycle ergometer test (median hs-cTnT concentration 10.6 ng/L vs 7.8 ng/L, P = 0.038). All levels returned to baseline within 24 h.

CONCLUSION

In professional athletes adapted to high-intensity intermittent exercise, hs-cTnT was significantly elevated after intermittent but not continuous exercise. This principle of specificity training should be considered when designing future studies to avoid misinterpretation of hs-cTnT elevation.

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 remodelling (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. Mid-regional pro-atrial natriuretic peptide (MR-proANP), N-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity troponin T (hscTn) were measured at rest, peak MECPET, and 60 minutes post-MECPET at both study time points. ET 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 VO₂ = 53.0 ± 5.9 vs. 67.3 ± 8.2 ml/kg/min, p<0.001). LV remodelling was characterized by an approximate 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 to chamber dilation.

Untargeted Metabolomics Profiling of an 80.5 km Simulated Treadmill Ultramarathon

Metabolomic profiling of nine trained ultramarathon runners completing an 80.5 km self-paced treadmill-based time trial was carried out. Plasma samples were obtained from venous whole blood, collected at rest and on completion of the distance (post-80.5 km). The samples were analyzed by using high-resolution mass spectrometry in combination with both hydrophilic interaction (HILIC) and reversed phase (RP) chromatography. The extracted putatively identified features were modeled using Simca P 14.1 software (Umetrics, Umea, Sweden). A large number of amino acids decreased post-80.5 km and fatty acid metabolism was affected with an increase in the formation of medium-chain unsaturated and partially oxidized fatty acids and conjugates of fatty acids with carnitines. A possible explanation for the complex pattern of medium-chain and oxidized fatty acids formed is that the prolonged exercise provoked the proliferation of peroxisomes. The peroxisomes may provide a readily utilizable form of energy through formation of acetyl carnitine and other acyl carnitines for export to mitochondria in the muscles; and secondly may serve to regulate the levels of oxidized metabolites of long-chain fatty acids. This is the first study to provide evidence of the metabolic profile in response to prolonged ultramarathon running using an untargeted approach. The findings provide an insight to the effects of ultramarathon running on the metabolic specificities and alterations that may demonstrate cardio-protective effects.

How is cardiac troponin released from injured myocardium?

Cardiac troponin I and cardiac troponin T are nowadays the criterion biomarkers for the laboratory diagnosis of acute myocardial infarction due to their very high sensitivities and specificities for myocardial injury. However, still many aspects of their degradation, tissue release and elimination from the human circulation are incompletely understood. Myocardial injury may be caused by a variety of different mechanisms, for example, myocardial ischaemia, inflammatory and immunological processes, trauma, drugs and toxins, and myocardial necrosis is preceded by a substantial reversible prelethal phase. Recent experimental data in a pig model of myocardial ischaemia demonstrated cardiac troponin release into the circulation from apoptotic cardiomyocytes as an alternative explanation for clinical situations with increased cardiac troponin without any other evidence for myocardial necrosis. However, the comparably lower sensitivities of all currently available imaging modalities, including cardiac magnetic resonance imaging for the detection of particularly non-focal myocardial necrosis in patients, has to be considered for cardiac troponin test result interpretation in clinical settings without any other evidence for myocardial necrosis apart from increased cardiac troponin concentrations as well.

Evidence of direct cardiac damage following high-intensity exercise in chronic energy restriction: A case report and literature review

RATIONALE

Following prolonged endurance events such as marathons, elevated levels of cardiospecific biomarkers are commonly reported. Although transiently raised levels are generally not considered to indicate clinical myocardial damage, comprehension of this phenomenon remains incomplete. The popularity of high-intensity interval training highlights a paucity of research measuring cardiac biomarker response to this type of exercise. This a posteriori case report discusses the elevation of cardiac troponins (cTn) associated with short interval, high-intensity exercise.

PATIENT CONCERNS

In this case report, an apparently healthy 29-year-old recreationally active female presented clinically raised cardiac troponin I (cTnI) levels (>0.04 ng/mL), after performing high-intensity cycle ergometer sprints. As creatine kinase (CK) is expressed by multiple organs (e.g., skeletal muscle, brain, and myocardium), cTnI assays were performed to determine any changes in total serum CK levels not originating from skeletal muscle damage.

DIAGNOSIS

A posteriori the individual's daily energy expenditure indicated chronically low-energy availability. Psychometric testing suggested that the individual scored positive for disordered eating, highly for fatigue levels, and low in mental health components.

OUTCOMES

The current case report provides novel evidence of elevated cTnI occurring as a result of performing short duration, high intensity, cycle ergometer exercise in an individual with self-reported chronically depleted energy balance. A schematic to identify potentially "at risk" individuals is presented.

LESSONS

Considering this as a case report, results cannot be generalized; however, the main findings suggest that individuals who habitually restrict their calorie intake below their bodies' daily energy requirements, may have elevated biomarkers of exercise induced myocardial stress from performing high-intensity exercise.

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.

Influence of a 10-Day Mimic of Our Ancient Lifestyle on Anthropometrics and Parameters of Metabolism and Inflammation: The "Study of Origin"

Chronic low-grade inflammation and insulin resistance are intimately related entities that are common to most, if not all, chronic diseases of affluence. We hypothesized that a short-term intervention based on “ancient stress factors” may improve anthropometrics and clinical chemical indices. We executed a pilot study of whether a 10-day mimic of a hunter-gatherer lifestyle favorably affects anthropometrics and clinical chemical indices. Fifty-five apparently healthy subjects, in 5 groups, engaged in a 10-day trip through the Pyrenees. They walked 14 km/day on average, carrying an 8-kilo backpack. Raw food was provided and self-prepared and water was obtained from waterholes. They slept outside in sleeping bags and were exposed to temperatures ranging from 12 to 42°C. Anthropometric data and fasting blood samples were collected at baseline and the study end. We found important significant changes in most outcomes favoring better metabolic functioning and improved anthropometrics. Coping with “ancient mild stress factors,” including physical exercise, thirst, hunger, and climate, may influence immune status and improve anthropometrics and metabolic indices in healthy subjects and possibly patients suffering from metabolic and immunological disorders.

Influence of exercise intensity and duration on functional and biochemical perturbations in the human heart

KEY POINTS

Strenuous endurance exercise induces transient functional and biochemical cardiac perturbations that persist for 24-48 h. The magnitude and time-course of exercise-induced reductions in ventricular function and increases in cardiac injury markers are influenced by the intensity and duration of exercise. In a human experimental model, exercise-induced reductions in ventricular strain and increases in cardiac troponin are greater, and persist for longer, when exercise is performed within the heavy- compared to moderate-intensity exercise domain, despite matching for total mechanical work. The results of the present study help us better understand the dose-response relationship between endurance exercise and acute cardiac stress/injury, a finding that has implications for the prescription of day-to-day endurance exercise regimes.

ABSTRACT

Strenuous endurance exercise induces transient cardiac perturbations with ambiguous health outcomes. The present study investigated the magnitude and time-course of exercise-induced functional and biochemical cardiac perturbations by manipulating the exercise intensity-duration matrix. Echocardiograph-derived left (LV) and right (RV) ventricular global longitudinal strain (GLS), and serum high-sensitivity cardiac troponin (hs-cTnI) concentration, were examined in 10 males (age: 27 ± 4 years; V̇O2, peak : 4.0 ± 0.8 l min(-1) ) before, throughout (50%, 75% and 100%), and during recovery (1, 3, 6 and 24 h) from two exercise trials. The two exercise trials consisted of 90 and 120 min of heavy- and moderate-intensity cycling, respectively, with total mechanical work matched. LVGLS decreased (P < 0.01) during the 90 min trial only, with reductions peaking at 1 h post (pre: -19.9 ± 0.6%; 1 h post: -18.5 ± 0.7%) and persisting for >24 h into recovery. RVGLS decreased (P < 0.05) during both exercise trials with reductions in the 90 min trial peaking at 1 h post (pre: -27.5 ± 0.7%; 1 h post: -25.1 ± 0.8%) and persisting for >24 h into recovery. Serum hs-cTnI increased (P < 0.01) during both exercise trials, with concentrations peaking at 3 h post but only exceeding cardio-healthy reference limits (14 ng l(-1) ) in the 90 min trial (pre: 4.2 ± 2.4 ng l(-1) ; 3 h post: 25.1 ± 7.9 ng l(-1) ). Exercise-induced reductions in ventricular strain and increases in cardiac injury markers persist for 24 h following exercise that is typical of day-to-day endurance exercise training; however, the magnitude and time-course of this response can be altered by manipulating the intensity-duration matrix.

Serum cardiac troponin I analysis to determine the excessiveness of exercise intensity: A novel equation

Physical exertion is often promoted because of its beneficial health effects. This only holds true, however, as long as the optimal exercise intensity is not exceeded. If physical exertion becomes too strenuous or prolonged, cardiac injury or dysfunction may occur. Consequently, a significant elevation of the serum concentration of the sensitive and specific cardiac biomarker troponin I can be observed. In this article, we present the derivation of a novel equation that can be used to evaluate to what extent the intensity of conducted endurance exercise was excessive, based on a post-exercise assessment of serum cardiac troponin I. This is convenient, as exercise intensity is difficult for an athlete to quantify accurately and the currently used heart rate indices can be affected by various physiological and environmental factors. Serum cardiac troponin I, on the other hand, is a post-hoc parameter that directly reflects the actual effects on the myocardium and may therefore be a promising alternative. To our knowledge, this is the first method to determine relative exercise intensity in retrospect. We therefore believe that this equation can serve as a potentially valuable tool to objectively evaluate the benefits or harmful effects of physical exertion.

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.

Sports cardiology: lessons from the past and perspectives for the future

The possibility of myocardial damage as a result of endurance sport has been known about since ancient times. According to a leg-end, a soldier named Pheidippides (more likely Philippides) dropped dead after run-ning from war-torn Marathon to Athens with the news of victory. Millennia later, we do not know whether he was a soldier or a courier, or whether he really ran the entire 240 km from Athens to Sparta and then back from Marathon to Athens. What is clear however, is that his death went down in history as the first documented exercise-related death and provides a tangible starting-point for the discipline of sport cardiology. Sports cardiology today covers a broad range of areas; from patients with cardiomyopathies, coronary disease and metabolic syndrome through to fitness fans, high-performance athletes and those with physically demanding professions. The following editorial introduces the primary topics for discussion to be included in the F1000Research channel Sports cardiology with the hope that this will evoke open, controversial and broad discourse in the form of reviews and original research papers in this important field.

Alteração de biomarcadores de lesão miocárdica em atletas após a Maratona Internacional de São Paulo

INTRODUÇÃO: Apesar de a prática regular de exercício físico reduzir o risco de doença cardiovascular, estudos recentes têm documentado elevações em biomarcadores relacionados com danos cardíacos após exercícios prolongados em indivíduos aparentemente saudáveis. OBJETIVO: Investigar as alterações nos níveis de brain natriuretic peptide (BNP) e troponina T cardíaca (cTnT) em atletas amadores após uma maratona, assim como verificar as possíveis relações entre as alterações, antes e depois da prova, apresentada pelos dois biomarcadores e variáveis do teste cardiopulmonar. MÉTODOS: Estudamos 38 atletas do sexo masculino (40,9 ± 6,29 anos) antes e depois da Maratona Internacional de São Paulo, SP, Brasil. Foram realizadas coletas de sangue na veia antecubital para mensurar os biomarcadores cardíacos, cTnT e BNP 24h antes, imediatamente após e 24h após a maratona. Foi realizado teste cardiopulmonar máximo nas três semanas que antecederam a prova. RESULTADOS: Os valores de BNP e cTnT aumentaram imediatamente após a maratona (p<0,001) quando comparados com os valores basais. No terceiro momento (24h) os valores de troponina tiveram uma redução significativa caracterizando um retorno aos valores basais. Não encontramos correlação entre idade e variáveis referentes a intensidade da maratona, porém encontramos correlação dos biomarcadores com o tempo de conclusão da maratona. CONCLUSÃO: Diferentes causas de liberação podem ser assumidas para cTnT e BNP e, neste caso, parecem não refletir dano miocárdico devido ao comportamento da curva destes marcadores, além de não haver relação entre a liberação dos dois biomarcadores.

Altered ventricular mechanics after 60 min of high-intensity endurance exercise: insights from exercise speckle-tracking echocardiography

Transient reductions in myocardial strain coupled with cardiac-specific biomarker release have been reported after prolonged exercise (>180 min). However, it is unknown if 1) shorter-duration exercise (60 min) can perturb cardiac function or 2) if exercise-induced reductions in strain are masked by hemodynamic changes that are associated with passive recovery from exercise. Left ventricular (LV) and right ventricular global longitudinal strain (GLS), LV torsion, and high-sensitivity cardiac troponin T were measured in 15 competitive cyclists (age: 28 ± 3 yr, peak O2 uptake: 4.8 ± 0.6 l/min) before and after a 60-min high-intensity cycling race intervention (CRIT60). At both time points (pre- and post-CRIT60), strain and torsion were assessed at rest and during a standardized low-intensity exercise challenge (power output: 96 ± 8 W) in a semirecumbent position using echocardiography. During rest, hemodynamic conditions were different from pre- to post-CRIT60 (mean arterial pressure: 96 ± 1 vs. 86 ± 2 mmHg, P < 0.001), and there were no changes in strain or torsion. In contrast, during the standardized low-intensity exercise challenge, hemodynamic conditions were unchanged from pre- to post-CRIT60 (mean arterial pressure: 98 ± 1 vs. 97 ± 1 mmHg, not significant), but strain decreased (left ventricular GLS: −20.3 ± 0.5% vs. −18.5 ± 0.4%, P < 0.01; right ventricular GLS: −26.4 ± 1.6% vs. −22.4 ± 1.5%, P < 0.05), whereas LV torsion remained unchanged. Serum high-sensitivity cardiac troponin T increased by 345% after the CRIT60 (6.0 ± 0.6 vs. 20.7 ± 6.9 ng/l, P < 0.05). This study demonstrates that exercise-induced functional and biochemical cardiac perturbations are not confined to ultraendurance sporting events and transpire during exercise that is typical of day-to-day training undertaken by endurance athletes. The clinical significance of cumulative exposure to endurance exercise warrants further study.

Impact of an endurance training program on exercise-induced cardiac biomarker release

We evaluated the influence of a 14-wk endurance running program on the exercise-induced release of high-sensitivity cardiac troponin T (hs-cTnT) and NH2-terminal pro-brain natriuretic peptide (NT-proBNP). Fifty-eight untrained participants were randomized to supervised endurance exercise (14 wk, 3–4 days/wk, 120–240 min/wk, 65–85% of maximum heart rate) or a control group. At baseline and after the training program, hs-cTnT and NT-proBNP were assessed before and 5 min, 1 h, 3 h, 6 h, 12 h, and 24 h after a 60-min maximal running test. Before training, hs-cTnT was significantly elevated in both groups with acute exercise ( P < 0.0001) with no between-group differences. There was considerable heterogeneity in peak hs-cTnT concentration with the upper reference limit exceeded in 71% of the exercise tests. After training, both baseline and postexercise hs-cTnT were significantly higher compared with pretraining and the response of the control group ( P = 0.008). Acute exercise led to a small but significant increase in NT-proBNP, but this was not mediated by training ( P = 0.121). In summary, a controlled endurance training intervention resulted in higher pre- and postexercise values of hs-cTnT with no changes in NT-proBNP.

Regional and global left ventricular function following a simulated 5 km race in sports-trained adolescents

The effects of a short, high-intensity bout of exercise on cardiac systolic and diastolic function are not well understood in adolescent athletes. Consequently, the aims of the study were to evaluate global left ventricular (LV) systolic and diastolic function, as well as segmental wall motion responses (cardiac strain), prior to as well as 45 and 225 min following a simulated 5 km cross-country race. Twenty trained, adolescent males (age: 15.2 ± 0.7 years) volunteered for exercise testing. LV fractional shortening and the ratio of early (E) and late (A) peak flow velocities reflected global systolic and diastolic function, respectively. Peak longitudinal mitral annular septal tissue velocities were also determined during systole and diastole. Longitudinal strain (ε) and strain rates were determined across the LV. LV fractional shortening was significantly (P < 0.05) higher at 225 min post-race (37.6 ± 5.8%) compared to pre-race (34.5 ± 4.7%) and 45 min post-race (34.9 ± 5.4 %). This difference was abolished after adjusting for post-race heart rates. There was a significant (P < 0.05) decrease in the E:A ratio at both 45 min (2.04 ± 0.57) and 225 min post-race (2.20 ± 0.66) compared to the pre-race value (2.80 ± 0.68). When these data were adjusted for post-race heart rates, these pre-post-race differences in E:A ratio were abolished. There were no significant alterations in either tissue Doppler velocities or longitudinal ε. The evidence suggests that a 5 km race does not lead to any significant post-exercise attenuation in global or regional LV systolic and diastolic function in trained adolescents.

Exercise preconditioning-induced late phase of cardioprotection against exhaustive exercise: possible role of protein kinase C delta

The objective of this study was to investigate the late cardiac effect of exercise preconditioning (EP) on the exhaustive exercise-induced myocardial injury in rats and the role of protein kinase C (PKC) in EP. Rats were subjected to a run on the treadmill for four periods of 10 min each at 30 m/min with intervening periods of rest of 10 min as an EP protocol. The exhaustive exercise was performed 24 h after EP. PKC inhibitor chelerythrine (CHE) was injected before EP. The results showed that EP increased the running ability of rats, and alleviated the exhaustive exercise-induced injury in cardiomyocytes, but pretreatment with PKC inhibitor CHE did not abolish the late phase cardioprotection of EP. A significant increase of PKCδ, both at the protein level and the mRNA level in the left ventricular myocardium of rats, accompanied by its activated form (phosphorylated on Thr507, p-PKCδThr507) translocated to intercalated disks and was found in the late phase of EP. This circumstance was not attenuated by CHE. These results suggested that a high level of PKCδ might be involved in cardioprotection against myocardial damage, but if activated PKCδ at reperfusion took on a key role in cardioprotection was still an outstanding question.

Leisure-time aerobic physical activity, muscle-strengthening activity and mortality risks among US adults: the NHANES linked mortality study

BACKGROUND

Regular physical activity elicits multiple health benefits in the prevention and management of chronic diseases. We examined the mortality risks associated with levels of leisure-time aerobic physical activity and muscle-strengthening activity based on the 2008 Physical Activity Guidelines for Americans among US adults.

METHODS

We analysed data from the 1999 to 2004 National Health and Nutrition Examination Survey with linked mortality data obtained through 2006. Cox proportional HRs with 95% CIs were estimated to assess risks for all-causes and cardiovascular disease (CVD) mortality associated with aerobic physical activity and muscle-strengthening activity.

RESULTS

Of 10 535 participants, 665 died (233 deaths from CVD) during an average of 4.8-year follow-up. Compared with participants who were physically inactive, the adjusted HR for all-cause mortality was 0.64 (95% CI 0.52 to 0.79) among those who were physically active (engaging in ≥150 min/week of the equivalent moderate-intensity physical activity) and 0.72 (95% CI 0.54 to 0.97) among those who were insufficiently active (engaging in >0 to <150 min/week of the equivalent moderate-intensity physical activity). The adjusted HR for CVD mortality was 0.57 (95% CI 0.34 to 0.97) among participants who were insufficiently active and 0.69 (95% CI 0.43 to 1.12) among those who were physically active. Among adults who were insufficiently active, the adjusted HR for all-cause mortality was 44% lower by engaging in muscle-strengthening activity ≥2 times/week.

CONCLUSIONS

Engaging in aerobic physical activity ranging from insufficient activity to meeting the 2008 Guidelines reduces the risk of premature mortality among US adults. Engaging in muscle-strengthening activity ≥2 times/week may provide additional benefits among insufficiently active adults.

Competitive sports and the heart: benefit or risk?

BACKGROUND

Controversy surrounds the cardiac effects of competitive sports and the athlete's heart. In this review, we present and discuss the main cardiological findings in competitive athletes.

METHOD

Selective review of pertinent literature retrieved by a search with the keywords "athlete's heart," "ECG," "echocardiography," "endurance exercise," "longevity," and others.

RESULTS

Regular exercise leads to functional and structural adaptations that improve cardiac function. Athlete's heart, which develops rarely, is a typical finding in endurance athletes. This condition is characterized by physiological, harmonically eccentric hypertrophy of all cardiac chambers. The athlete's ECG can be used to distinguish physiological, training-related changes from pathological training-unrelated changes. The athlete's heart function is normal at rest and increases appropriately during exercise. The cardiac markers troponin and B-type natriuretic peptide are within the normal range in healthy athletes at rest, but can temporarily be mildly elevated after exhausting endurance-exercise, without evidence of myocardial damage. The epidemiological data suggest that participation in competitive sports increases life expectancy.

CONCLUSION

Competitive exercise does not induce cardiac damage in individuals with healthy hearts, but does induce physiological functional and structural cardiac adaptations which have positive effects on life expectancy.