Prolonged exercise should be considered alongside typical symptoms of acute myocardial infarction when evaluating increases in cardiac troponin T

Cardiac biomarker responses following high-intensity interval and continuous exercise: the influence of ACE-I/D gene polymorphism and training status in men

This study aimed to investigate the relationship between pre- and postexercise cardiac biomarker release according to athletic status (trained vs. untrained) and to establish whether the I/D polymorphism in the angiotensin-converting enzyme (ACE) gene had an influence on cardiac biomarkers release with specific regard on the influence of the training state. We determined cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in 29 trained and 27 untrained male soccer players before and after moderate-intensity continuous exercise (MICE) and high-intensity interval exercise (HIIE) running tests. Trained soccer players had higher pre (trained: 0.014 ± 0.007 ng/mL; untrained: 0.010 ± 0.005 ng/mL) and post HIIE (trained: 0.031 ± 0.008 ng/mL; untrained: 0.0179 ± 0.007) and MICE (trained: 0.030 ± 0.007 ng/mL; untrained: 0.018 ± 0.007) cTnI values than untrained subjects, but the change with exercise (ΔcTnI) was similar between groups. There was no significant difference in baseline and postexercise NT-proBNP between groups. NT-proBNP levels were elevated after both HIIE and MICE. Considering three ACE genotypes, the mean pre exercise cTnI values of the trained group (DD: 0.015 ± 0.008 ng/mL, ID: 0.015 ± 0.007 ng/mL, and II: 0.014 ± 0.008 ng/mL) and their untrained counterparts (DD: 0.010 ± 0.004 ng/mL, ID: 0.011 ± 0.004 ng/mL, and II: 0.010 ± 0.006 ng/mL) did not show any significant difference. To sum up, noticeable difference in baseline cTnI was observed, which was related to athletic status but not ACE genotypes. Neither athletic status nor ACE genotypes seemed to affect the changes in cardiac biomarkers in response to HIIE and MICE, indicating that the ACE gene does not play a significant role in the release of exercise-induced cardiac biomarkers indicative of cardiac damage in Iranian soccer players.NEW & NOTEWORTHY Our study investigated the impact of athletic status and angiotensin-converting enzyme (ACE) gene I/D polymorphism on cardiac biomarkers in soccer players. Trained players showed higher baseline cardiac troponin I (cTnI) levels, whereas postexercise ΔcTnI remained consistent across groups. N-terminal pro-brain natriuretic peptide increased after exercise in both groups, staying within normal limits. ACE genotypes did not significantly affect pre-exercise cTnI. Overall, athletic status influences baseline cTnI, but neither it nor ACE genotypes significantly impact exercise-induced cardiac biomarker responses in this population.

Regulation of Circulatory Muscle-specific MicroRNA during 8 km Run

Acute prolonged endurance running has been shown to alter muscle-specific circulating microRNA (miRNA) levels. Here, eighteen participants completed an 8 km run. We assessed the levels of hsa-miR-1-3p, -133a-3p, -133b, and -206 and their correlation with conventional biomarkers following exercise. Compared to before exercise (Pre), 8 km run significantly increased the lactate level immediately after exercise (0 h). Myoglobin (Mb) level increased at 0 h while creatine kinase (CK) level increased 24 h after exercise (24 h). The levels of creatine kinase MB isoenzyme (CK-MB) and cardiac troponin I (cTnI) were all elevated at 24 h and within the normal physiological range; The levels of hsa-miR-1-3p, -133a-3p, -133b significantly increased at 0 h but only hsa-miR-133a-3p still elevated at 24 h. Only hsa-miR-206 level decreased at 24 h; Additionally, the changes of hsa-miR-1-3p and hsa-miR-133a-3p were correlated with Mb at 24 h. These findings suggest that muscle-specific miRNA elevation in plasma is likely physiological and that these miRNA may be used as potential biomarkers for load monitoring in individuals.

Intense sport practices and cardiac biomarkers

Biomarkers are well established for the diagnosis of myocardial infarction, heart failure and cardiac fibrosis. Different papers on cardiac biomarker evolution during exercise have been published in the literature and generally show mild to moderate elevations. However, the mechanism responsible for these elevations, reflecting physiological or even pathophysiological changes, still has to be clearly elucidated. There are also indications of higher cardiac risk in poorly trained athletes than in well-trained athletes. Whether regular repetition of intensive exercise might lead, in the longer term, to fibrosis and heart failure remains to be determined. In this review, we summarized the main research about the effects of intense exercise (in particular, running) on cardiac biomarkers (including troponins, natriuretic peptides, etc.). We found that cardiac fibrosis biomarkers seemed to be the most informative regarding the biological impact of intense physical activity.

Acute effects of recreational soccer on inflammatory response and cardiac and skeletal muscle damage indicators

Introduction: Previous studies have indicated that acute bouts of strenuous, long duration exercise induce significant increases in the inflammatory profile and cardiovascular risk markers. Although recreational soccer (RS) is a widespread activity, there are no data on this topic. Thus, the aim of this study was to examine RS-induced changes in inflammatory, cardiac, and skeletal muscle damage indicators in young and middle-aged males.

Methods: Twelve young and 11 middle-aged males participated in the study. The participants played 6v6 1 h RS, where heart rate (HR) responses and external loads (distance covered, number of accelerations/decelerations) were determined. Blood samples were taken immediately prior to and following the matches, and 2 h, 4 h, 24 h, 48 h, and 72 h later.

Results: Absolute HR responses and the number of accelerations and decelerations were higher in young participants than the middle-aged participants (p < 0.05). RS increased high sensitivity cardiac troponin I (hs-cTnI) in almost all participants. A total of 83.3% of the young participants exceeded the upper reference limit (URL), whereas none of the middle-aged participants exceeded the URL. Hs-cTnI levels returned to baseline after 24 and 48 h in the middle-aged and young participants, respectively. High sensitivity C-reactive protein (hs-CRP) and creatine kinase (CK) increased in the middle-aged participants (p < 0.05), and in the young participants, though not significantly (p > 0.05). RS also led to significant increases in lactate dehydrogenase (LDH) in both groups (p < 0.05). Hs-CRP, CK, and LDH values returned to baseline levels within 48 to 72 h, except for the LDH values of the young participants.

Conclusion: RS induced short-term increases in cardiac and skeletal muscle damage markers and the inflammatory profile in young and middle-aged RS participants.

Relationship Between Morning Heart Rate Variability and Creatine Kinase Response During Intensified Training in Recreational Endurance Athletes

Specific physiological responses and their relationship were analyzed in 12 recreational endurance athletes (43.8 ± 7.9 years) during a period of intensified cycling training. Heart rate (HR), HR variability (HRV), serum creatine kinase (S-CK) and haematocrit (Hct) were measured in the mornings before (PRE) and following three consecutive days of intensified training (POST 1–3). Morning HR increased during this period (PRE: 52.2 ± 6.7 bpm, POST 1: 58.8 ± 7.0 bpm, POST 2: 58.5 ± 8.1 bpm, POST 3: 57.9 ± 7.2 bpm; F(3,33) = 11.182, p < 0.001, η_p² = 0.554). Parasympathetic HRV indices decreased from PRE to POST (F(3,33) ≥ 11.588, p < 0.001, η_p² ≥ 0.563), no effect was found for sympathetically modulated HRV (F(3,33) = 2.287, p = 0.101, η_p² = 0.203). Hct decreased (PRE: 49.9 ± 4.0%, POST 1: 46.5 ± 5.1%, POST 2: 45.5 ± 3.8%, POST 3: 43.2 ± 3.4%; F(3,33) = 11.909, p < 0.001, η_p² = 0.520) and S-CK increased during the training period (PRE: 90.0 ± 32.1 U/L, POST 1: 334.7 ± 487.6 U/L, POST 2: 260.1 ± 303.4 U/L, POST 3: 225.1 ± 258.8 U/L; F(3,33) = 3.996, p = 0.017, η_p² = 0.285). S-CK release was associated with HR (r = 0.453, p = 0.002, n = 44), RMSSD (r = −0.494, p = 0.001, n = 44) and HF-Power (r = −0.490, p = 0.001, n = 44). A period of intensified training was associated with haemodilution, parasympathetic withdrawal and S-CK-increase. Cardiac autonomic control at morning rest correlated with the S-CK-release; and thus, may serve as a practical mean to complementary monitor and prescribe training load in this population.

Effect of Health and Training on Ultrasensitive Cardiac Troponin in Marathon Runners

PURPOSE

Cardiac troponin (cTn) is the gold standard biomarker for assessing cardiac damage. Previous studies have demonstrated increases in plasma cTn because of extreme exercise, including marathon running. We developed an easy-to-use, ultrasensitive assay for cardiac troponin I (cTnI) by combining single-molecule counting (SMC™) technology with dried blood spot (DBS) collection techniques and validated the assay on a cohort of marathon runners by correlating postmarathon cTnI elevations with training or risk variables.

METHODS

An SMC-DBS method was developed for accurate and reproducible measurement of cTnI in fingerstick whole blood. Samples were collected from 42 runners both before and immediately after running a marathon. A similar collection was obtained from 22 non-running control individuals. Pre- and postrace questionnaires containing health and training variables were correlated with cTnI concentration.

RESULTS

The assay quantified cTnI in all controls and marathon runners, both before and after the race. Prerace concentrations were significantly higher in marathon runners vs controls (median 3.1 vs 0.4 pg/mL; P < 0.0001). Immediate postmarathon concentrations were increased in 98% of runners (median elevation, 40.5 pg/mL; P < 0.001), including many above traditional cutoffs for acute myocardial infarction. Several health and training variables trended toward significant correlation with cTnI elevations.

CONCLUSION

While further studies are needed to better understand the mechanisms and clinical implications of exercise-induced cTnI elevations, the present study suggests several variables that may be associated with such elevations and demonstrates a simple, cost-effective method for monitoring cTnI during exercise, managing chronic disease, and/or for assessing risk in large populations.

Race predictors and hemodynamic alteration after an ultra-trail marathon race

OBJECTIVE

Unique rough-terrain ultra-trail running races have increased in popularity. Concerns regarding the suitability of the candidates make it difficult for organizers to manage safety regulations. The purpose of this study was to identify possible race predictors and assess hemodynamic change after long endurance races.

METHODS

We studied 228 runners who competed in a 66 km-trail running race. A questionnaire and noninvasive hemodynamic flow assessment including blood pressure, heart rate, stroke volume, stroke volume variation, systemic vascular resistance, cardiac index, and oxygen saturation were used to determine physiologic alterations and to identify finish predictors. One hundred and thirty volunteers completed the questionnaire, 126 participants had a prerace hemodynamic assessment, and 33 of these participants completed a postrace assessment after crossing the finish line. The participants were divided into a finisher group and a nonfinisher group.

RESULTS

The average age of all runners was 37 years (range of 24-56 years). Of the 228 runners, 163 (71.5%) were male. There were 189 (82.9%) finishers. Univariable analysis indicated that the finish predictors included male gender, longest distance ever run, faster running records, and lower diastolic pressure. Only a lower diastolic pressure was a significant predictor of race finishing (diastolic blood pressure 74-84 mmHg: adjusted odd ratio 3.81; 95% confidence interval [CI] =1.09-13.27 and diastolic blood pressure <74 mmHg: adjusted odd ratio 7.74; 95% CI =1.57-38.21) using the figure from the multivariable analysis. Among the finisher group, hemodynamic parameters showed statistically significant differences with lower systolic blood pressure (135.9±14.8 mmHg vs 119.7±11.3 mmHg; p<0.001), faster heart rate (72.6±10.7 bpm vs 96.4±10.4 bpm; p<0.001), lower stroke volume (43.2±13.6 mL vs 29.3±10.1 mL; p<0.001), higher stroke volume variation; median (interquartile range) (36% [25%-58%] vs 53% [33%-78%]; p<0.001), and lower oxygen saturation (97.4%±1.0% vs 96.4%±1.0%; p<0.001). Systemic vascular resistance and cardian index did not change significantly.

CONCLUSION

The only race finishing predictor from the multivariable analysis was lower diastolic pressure. Finishers seem to have a hypovolemic physiologic response and a lower level of oxygen saturation.

Morbidities in the ultra-athlete and marathoner

The cardiovascular benefits of habitual exercise are well documented. In the current era, more of the population is exceeding the recommendations for physical activity as the popularity of endurance events increases. Recent data have proposed a U-shaped relationship between exercise intensity and cardiovascular outcomes. Regular participation in endurance activities has been shown to result in structural and functional changes in the heart. This re-modelling may be the substrate for cardiac dysfunction or arrhythmias. The risk of sudden cardiac death may also be elevated; however, in most cases of sudden cardiac death, the cause can be linked to an underlying cardiac pathology where exercise acted as the trigger for a lethal arrhythmia. This article serves to review whether excessive exercise may result in harm in some athletes.

Troponin and exercise

Cardiac troponins are the preferred biomarkers in diagnostic of myocardial infarction, but these markers also can rise in response to exercise. Multiple studies have assessed troponins post-exercise, but the results have varied and there have been disagreements about the mechanism of troponin release. The aim of this paper was to review the literature, and to consider factors and mechanisms regarding exercise-induced increase of troponin. 145 studies were found after a search in pubmed and inclusion of additional articles found in the reference list of the first articles. Results showed that troponin rises in 0-100% of subjects after prolonged heavy exercise like marathon, but also after short-term and intermittent exercise like 30min of running and basketball. The variation can be due to factors like intensity, age, training experience, variation in sample size, blood sample timing and troponin assay. The pattern of troponin level post-exercise corresponds to release from the cytosolic compartment of cardiomyocytes. Increased membrane permeability might be caused by production of reactive oxygen species or alterations in calcium, pH, glucose/fat metabolism or in communication between integrins. Other suggested mechanisms are increased cardiovascular stress, inflammation, vasculitis, release of troponin degradation products in "blebs", dehydration, impaired renal clearance and expression of cardiac troponin in skeletal muscle. It can be concluded that both heavy and light exercise may cause elevated troponin, which have to be considered when patient are suspected to have a myocardial infarction. Several factors probably influence post-exercise levels of troponin, but the mechanism of release is most likely physiologic.

Low-Volume Intense Exercise Elicits Post-exercise Hypotension and Subsequent Hypervolemia, Irrespective of Which Limbs Are Exercised

Introduction: Exercise reduces arterial and central venous blood pressures during recovery, which contributes to its valuable anti-hypertensive effects and to facilitating hypervolemia. Repeated sprint exercise potently improves metabolic function, but its cardiovascular effects (esp. hematological) are less well-characterized, as are effects of exercising upper versus lower limbs. The purposes of this study were to identify the acute (<24 h) profiles of arterial blood pressure and blood volume for (i) sprint intervals versus endurance exercise, and (ii) sprint intervals using arms versus legs.

Methods: Twelve untrained males completed three cycling exercise trials; 50-min endurance (legs), and 5^*30-s intervals using legs or arms, in randomized and counterbalanced sequence, at a standardized time of day with at least 8 days between trials. Arterial pressure, hemoglobin concentration and hematocrit were measured before, during and across 22 h after exercise, the first 3 h of which were seated rest.

Results: The post-exercise hypotensive response was larger after leg intervals than endurance (AUC: 7540 ± 3853 vs. 3897 ± 2757 mm Hg·min, p = 0.049, 95% CI: 20 to 6764), whereas exercising different limbs elicited similar hypotension (arms: 6420 ± 3947 mm Hg·min, p = 0.48, CI: −1261 to 3896). In contrast, arterial pressure at 22 h was reduced after endurance but not after leg intervals (−8 ± 8 vs. 0 ± 7 mm Hg, p = 0.04, CI: 7 ± 7) or reliably after arm intervals (−4 ± 8 mm Hg, p = 0.18 vs. leg intervals). Regardless, plasma volume expansion at 22 h was similar between leg intervals and endurance (both +5 ± 5%; CI: −5 to 5%) and between leg and arm intervals (arms: +5 ± 7%, CI: −8 to 5%).

Conclusions: These results emphasize the relative importance of central and/or systemic factors in post-exercise hypotension, and indicate that markedly diverse exercise profiles can induce substantive hypotension and subsequent hypervolemia. At least for endurance exercise, this hypervolemia may not depend on the volume of post-exercise hypotension. Finally, endurance exercise led to reduced blood pressure the following day, but sprint interval exercise did not.

Diagnosis, Incidence, and Clinical Implications of Perioperative Myocardial Injury in Vascular Surgery

Introduction:

Routine measurement of cardiac biomarkers such as troponin T (TnT) is recommended perioperatively, especially in high-risk vascular surgery. Long-term prognosis is worse even in those with nonspecific perioperative myocardial injury. However, a clear understanding of these biomarker profiles and how they should affect patient management is lacking.

Methods:

We examined the perioperative profile of high-sensitivity TnT (hsTnT) release in 85 patients undergoing elective major vascular surgery. Plasma hsTnT was measured preoperatively, at 6, 12, and 24 hours postoperatively, and then every 24 hours for a maximum of 5 days. Significant elevations in hsTnT with/without clinical indicators of ischemia were used to diagnose myocardial infarction or injury.

Results:

A high incidence of myocardial injury was evident (46% had elevated hsTnT); only 5% were associated with myocardial infarction, and 41% were due to myocardial injury.

Conclusions:

This study emphasizes the high incidence of perioperative myocardial injury and stress in vascular surgery as revealed by the use of the robust and very sensitive biomarker of myocardial damage, hsTnT. The high availability and swift development of increasingly sensitive assays allow detection of abnormal elevated hsTnT levels in a higher proportion of the population. Consequent challenges are the reduced specificity to separate acute events as well as to deduce the prognostic value of elevations due to confusing criteria; this is especially the case in a patient group with multiple comorbidities that affect hsTnT levels chronically.

An update on the Boston Marathon as a research laboratory

PURPOSE/METHODS

The Boston Athletic Association's annual marathon, also referred to as BAA in this article, continues to be a source of subjects for exercise and endurance performance research. We performed a systematic literature review of BAA studies published in the 7 years since our prior report.

RESULTS

We identified 20 articles published from January 2008 to February 2015. Nine were related to cardiology; six were related to exercise physiology; four were related to metabolism; and one was related to marathon qualifying times. As in our prior, report cardiovascular studies remained the dominant topic, but with risk factors for atherosclerosis and thrombosis as the present focus.

CONCLUSION

Cardiac issues remain the largest subject area for BAA studies, but with more emphasis on the effect of prolonged exercise on atherosclerotic and thrombotic risk factors. This shift is associated with an increase in marathon participation by older, recreational runners at increased risk of cardiac complications due to exercise.

Acute changes to biomarkers as a consequence of prolonged strenuous running

BACKGROUND

A single bout of strenuous running exercise results in perturbations to numerous biomarkers. An understanding of these is important when analysing samples from individuals who have recently performed such exercise.

METHODS

A literature search was undertaken using the search terms, exercise, marathon and delayed onset of muscle soreness. The search was then refined using the terms for key biomarkers known to be altered by exercise.

RESULTS

The magnitude of changes to biomarkers is proportional to the severity of the running bout. Familiar, moderate intensity running exercise produces brief transient changes in common biomarkers such as lactate, whereas more severe bouts of running exercise, such as marathons and ultra-marathon events can produce changes to biomarkers that are normally associated with pathology of the muscles, liver and heart. Examples being changes to concentrations and/or activity of myoglobin, leucocytes, creatine kinase, bilirubin, cardiac troponins, lactate dehydrogenase, alanine aminotransferase and aspartate aminotransferase. While persisting for longer, these changes are also transient and full recovery occurs within days, without any apparent long-term adverse consequences. Additionally, unfamiliar exercise involving forceful eccentric muscle contractions, such as running downhill, can cause increases in creatine kinase and delayed onset of muscle soreness that peaks 36-72 h after the exercise bout.

CONCLUSIONS

Strenuous running exercise can produce changes to biomarkers that are normally associated with disease and injury, but these do not necessarily reflect chronic pathology.

Exercise preconditioning provides early cardioprotection against exhaustive exercise in rats: potential involvement of protein kinase C delta translocation

The objective of this study was to investigate the early cardioprotective effect of exercise preconditioning (EP) on the exhaustive exercise-induced myocardial injury in rats and the role of protein kinase C delta isoform (PKCδ) in EP. Rats were subjected to 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 0.5 h after EP. PKC inhibitor chelerythrine (CHE) was injected before EP. Our results showed that EP markedly attenuated the exhaustive exercise-induced myocardial ischemia/hypoxia, ultrastructural damage, high serum cTnI, and NT-proBNP levels. CHE injection before EP did not abolish the protection of EP. Both exhaustive exercise and EP produced a significant increase in PKCδ and p-PKCδ(Thr507) protein levels in cardiomyocytes. However, the immunostaining of p-PKCδ(Thr507) in EP cardiomyocytes was primarily localized to intercalated disks and nuclei while the exhaustive exercise-induced high level p-PKCδ(Thr507) was mainly distributed in the cytoplasm. Moreover, the high PKCδ and p-PKCδ(Thr507) levels in exhaustive exercise were significantly down-regulated by EP. CHE did not attenuate the expressions of PKCδ and p-PKCδ(Thr507). These results indicate that an appropriate activation and translocation of PKCδ may represent a mechanism whereby EP can exert an early cardioprotection against exhaustive exercise-induced myocardial injury.

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.

Marathon running as a cause of troponin elevation: a systematic review and meta-analysis

BACKGROUND

Cardiac troponin (cTn) has high sensitivity and specificity for myocardial injury in acute coronary syndrome. Our objective was to review the published literature regarding the incidence of cTn elevations in marathon runners.

METHODS

Systematic review and meta-analysis of observational studies published before September 2009. We included studies of patients who had completed a marathon and had serum cTn levels within 24 hours. The primary outcome was the odds ratio for conversion of a normal pre-marathon cTn to an elevated post-marathon cTn. Secondary outcomes included the pooled prevalence of cTn elevation and comparison of the odds ratio for post-marathon elevation of cTnI versus cTnT.

RESULTS

Sixteen studies of 939 participants met criteria for inclusion. The mean age was 39 ± 4 years and patients were 74 ± 14% male. There were 6 pre-marathon cTn elevations and 579 post-race elevations. The pooled odds ratio for converting from a normal pre-race to an elevated post-race cTn was 51.84 (95% CI 16-168, I² = 66%, P < 0.001). The pooled incidence of a post-marathon cTn elevation was 51% (95% CI 33-69, I² = 98%, P < 0.001) of all runners. For the primary outcome there was no significant publication bias. Age and gender were not associated, but publication date and assay sensitivity was associated with cTn elevation. cTnI was less commonly elevated versus cTnT.

CONCLUSIONS

The available data demonstrate that cTn levels are frequently elevated after a marathon with unclear cardiovascular significance. This elevation of cTn appears to be consistent among a diverse patient population.

Troponin elevation in coronary vs. non-coronary disease

Acute myocardial infarction is defined as myocardial cell death due to prolonged myocardial ischaemia. Cardiac troponins (cTn) are the most sensitive and specific biochemical markers of myocardial injury and with the new high-sensitivity troponin methods very minor damages on the heart muscle can be detected. However, elevated cTn levels indicate cardiac injury, but do not define the cause of the injury. Thus, cTn elevations are common in many disease states and do not necessarily indicate the presence of a thrombotic acute coronary syndrome (ACS). In the clinical work it may be difficult to interpret dynamic changes of troponin in conditions such as stroke, pulmonary embolism, sepsis, acute perimyocarditis, Tako-tsubo, acute heart failure, and tachycardia. There are no guidelines to treat patients with elevated cTn levels and no coronary disease. The current strategy of treatment of patients with elevated troponin and non-acute coronary syndrome involves treating the underlying causes. The aim of this paper is to review data from studies of non-ACS patients with acutely elevated troponin who in clinical practice may be difficult to discriminate from ACS patients.

Exercise-induced cardiac troponin elevation: evidence, mechanisms, and implications

Regular physical exercise is recommended for the primary prevention of cardiovascular disease. Although the high prevalence of physical inactivity remains a formidable public health issue, participation in exercise programs and recreational sporting events, such as marathons and triathlons, is on the rise. Although regular exercise training reduces cardiovascular disease risk, recent studies have documented elevations in cardiac troponin (cTn) consistent with cardiac damage after bouts of exercise in apparently healthy individuals. At present, the prevalence, mechanism(s), and clinical significance of exercise-induced cTn release remains incompletely understood. This paper will review the biochemistry, prevalence, potential mechanisms, and management of patients with exercise-induced cTn elevations.

Cardiac troponin I is released following high-intensity short-duration exercise in healthy humans

It has been previously shown that cardiac troponin (cTn) is released in response to prolonged endurance exercise. The influence of short-duration high-intensity exercise upon the release of cTn is not known. We examined cardiac troponin I (cTnI) release pre-, during and post-30 min of high-intensity running exercise in eight recreationally active males (age 29±3 years; VO2peak 53±11 ml kg min(-1)). Following exercise, cTnI increased in six of the eight participants. Four participants showed a minimal response (<0.05 µg/l) post-exercise. In contrast, two participants showed a progressive increase in cTnI (>0.1 µg/l) following exercise which peaked 3-4 h post-exercise. cTnI returned below the detection limit of the assay in all bar one of the participants 24 h post-exercise. These data are the first to show that cTnI can be released following short-duration high-intensity exercise. Clinicians should be aware that exercise-induced release of cTnI is not limited to prolonged endurance activity.

Myocardial function in older male amateur marathon runners: assessment by tissue Doppler echocardiography, speckle tracking, and cardiac biomarkers

BACKGROUND

Participation of older men in endurance races continues to increase. Recent studies on marathon runners raised concerns about a transient myocardial dysfunction and damage. The aim of our study was to compare the extent of marathon-induced myocardial dysfunction in young and older runners and to identify its potential correlation to elevated cardiac biomarkers.

METHODS

Twenty-eight older (aged 60-72 years) and 50 younger (22-59 years) male amateur athletes who participated in the 2006 Berlin Marathon were included in the study and examined by echocardiography (including tissue Doppler and speckle tracking echocardiography) and blood tests (including troponin T [TnT], N-terminal pro brain natriuretic peptide [NT-proBNP]) before, immediately after, and 2 weeks after the race.

RESULTS

Immediately after the marathon, there was no sign of systolic myocardial dysfunction (increase in fractional shortening, baseline 39.9% +/- 7.6% vs post 46.8% +/- 9.2%, P < .001, unchanged septal basal longitudinal 2-dimensional strain: 17.1% +/- 2.9%, 17.7% +/- 3.2%, P = .11). As a marker of diastolic function, E/E' was not altered significantly (7.6 +/- 2.1, 8.7 +/- 3.5, P = .15). The deceleration time of E and E' decreased in both groups immediately after the race, indicating a transient adaptation of diastolic myocardial function. Strain of the right ventricular free wall was decreased in the mid and apical segments after the race in both groups with normalization during follow-up. Tricuspid annular plane systolic excursion was not altered. Some 53.8% of all runners had increases in TnT or NT-proBNP after the race. Some 32% of controls and 29% of older runners had elevated levels of NT-proBNP (P = .75, TnT: 44% vs 29% P = .18). There was no correlation between NT-proBNP and TnT increase. The increases in biomarkers were not correlated to echocardiography parameters of systolic, diastolic, or right-sided heart dysfunction or to age, training level, running time, or renal function. All parameters returned to normal ranges after 2 weeks.

CONCLUSION

Left ventricular systolic function is preserved after a marathon in older runners. There are right ventricular functional changes as a sign of prolonged myocardial work load. There is no significant difference between older and young runners regarding transient diastolic dysfunction or biomarker release. The latter is not associated with echocardiography parameters of myocardial dysfunction.

Changes in vascular and cardiac function after prolonged strenuous exercise in humans

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

Exercise-induced cardiac troponin T release: a meta-analysis

PURPOSE

Cardiac troponin T (cTnT) is a highly specific marker of myocardial damage and used clinically in the diagnosis of acute myocardial infarction (AMI). Release of cTnT has been demonstrated in several small studies after endurance exercise. The purpose of this study was to explore, using a meta-analytic approach, the incidence of postexercise cTnT release after endurance exercise.

METHODS

Articles identified via Pubmed, SportDiscus, and Embase (1997-2006) searches using the key words cardiac troponin T, cTnT, cardiac biomarkers, and exercise; a search of bibliographies; and consultation with experts in the field were entered into a random-effects meta-analysis. We identified 26 relevant studies (1120 cases). Age, gender, and body mass of participants, as well as exercise mode and duration, were explored as possible moderator variables with meta-regressions.

RESULTS

Postexercise cTnT levels exceeded the assay detection limit in 47% of participants (95% CI = 39-56%). The detection of postexercise cTnT after cycling events was approximately half that of running events (27 vs 52%, P = 0.042). The detection of postexercise cTnT decreased slightly as event duration increased (P = 0.022) and mean body mass decreased (P = 0.0033). Postexercise detection of cTnT was not affected by age (P= 0.309) and was only slightly higher for studies with more males in the sample (P = 0.028).

CONCLUSIONS

Exercise-induced cTnT release is apparent in almost half of the endurance athletes who have been studied to date. Relatively heavy individuals competing in shorter endurance events, primarily running marathons, are slightly more likely to demonstrate elevated cTnT postexercise than other athletes. These data are useful for clinicians evaluating athletes with cTnT elevations after competitive endurance exercise events.

Altered left ventricular diastolic filling following a marathon is a reproducible phenomenon

The present study examined the reproducibility of alterations in left ventricular function and cardiac biomarkers in a cohort of athletes following two marathons, one year apart. Eight participants in the 2004 and 2005 London Marathons were tested pre- and post-race via echocardiography and humoral analysis. Reductions in diastolic filling, unrelated to loading or heart rate, following both marathons were reproducible within individuals, which may be a function of exercise duration. In contrast, exercise-induced cardiac troponin release was inconsistent.

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.

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.