Serum Cardiac Troponin T in Adolescent Runners: Effects of Exercise Intensity and Duration

Treadmill running intensity and post-exercise increase in plasma cardiac troponin I and T-A pilot study in healthy volunteers

BACKGROUND

Plasma concentrations of cardiac troponins increase in healthy individuals after strenuous training, but the response to lower exercise intensities has not been characterized.

AIM

To determine whether exercise at moderate intensity significantly increases plasma cardiac troponins measured with different assays in healthy recreational athletes.

METHODS

Twenty-four self-reported healthy volunteers were instructed to complete three 60-min bouts of treadmill running at variable intensities: High-intensity training (HIT) including a maximal exercise test and an anaerobic threshold test followed by training at 80%-95% of maximum heart rate (HRmax ), Moderate-intensity training (MIT) at 60%-75% of HRmax , and Low-intensity training (LIT) at 45%-55% of HRmax . Blood samples were collected before and at 2, 4, and 6 h after HIT and 4 h after MIT and LIT. Troponin I and T were measured in plasma samples with assays from Abbot, Siemens, and Roche.

RESULTS

Plasma troponins measured with all assays were significantly increased compared to baseline after HIT but not after LIT. After HIT, the fraction of all participants with one or more values above the assay-specific 99th percentiles ranged from 13% to 61%. The biomarker criteria for acute myocardial injury were met after HIT for troponin T in 75% of female participants having no clinical evidence of coronary artery disease.

CONCLUSION

High-intensity, but not moderate- or low-intensity, training for 60 min induced a potentially clinically significant increase in plasma cardiac troponins in healthy volunteers. Results exceeding the population 99th percentiles were most frequent with the troponin T assay.

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.

Effect of Training Load on Post-Exercise Cardiac Biomarkers in Healthy Children and Adolescents: A Systematic Review of the Existing Literature

BACKGROUND

Postexercise release of cardiac biomarkers (cardiac troponins, cTn, and N-terminal pro b-type natriuretic peptide, NT-proBNP) is a well-known phenomenon in adults, although it remains unclear how it manifests in children. The aim of this review is to compare the pre-exercise with the post-exercise measurement of serum cardiac biomarkers, as well as to analyze their post-exercise release based on age, sex, and exercise intensity and duration.

METHODS

The terms troponin, football, swimmers, marathon, run, and exercise were used in a literature search at National Library of Medicine. The search was further refined by adding the keywords athletes, children, adolescents, and sport.

RESULTS

Fifteen pediatric studies and four studies with a mixed population of adults and children totaled 19 studies for the final analysis. In addition to them, some adult studies have been included for comparison. The kinetics of the cTn and NT-proBNP response after exercise have been the subject of our interest. While the impact of sport type, age, and sex has not yet been fully characterized, the existing data points to considerable impacts of sport intensity and duration on post-exercise biomarkers elevation. Most of the findings came from endurance sports, but the evidence is sparse. Furthermore, there is only limited data on women and less on young adults, African Caribbeans, and professional athletes.

CONCLUSIONS

Both amateur and competitive athletes can exhibit post-exercise release of both cTn and NT-proBNP. This is transient and lacks pathological significance, in contrast with adult population, in which exercise-induced increases in in these biomarker levels may not always be benign. While NT-proBNP release is still primarily driven by activity duration, cTnT release is additionally affected by exercise intensity. To define individual ranges of normality for postexercise cTn and NT-proBNP elevation, the role of several confounders (age, sex, sport type/intensity etc.) remains to be further elucidated.

A comparison of modelled serum cTnT and cTnI kinetics after 60 min swimming

Post-exercise elevations of cardiac troponin T (cTnT) and I (cTnI) are often used in isolation but interpreted interchangeably. Research suggests, however, that post-exercise cTn kinetic might differ with each isoform. In this cross-sectional observational study, we collected blood samples before, immediately after (5 minutes), and at 1-, 3-, 6-, 12-, and 24-hours post-exercise in a mixed cohort of 56 participants after a 60-min (age range from 14 to 22, 57.1% female). swimming trial. Cardiac troponin kinetics were modeled using Bayesian mixed-effects models to estimate time to peak (TTP) and peak concentration (PC) for each isoform, while controlling for participants sex, tanner stage and average relative heart rate during the test. Exercise induced an elevation of cTnT and cTnI in 93% and 75% of the participants, respectively. Cardiac troponin T peaked earlier, at 2.9 h (CI: 2.6 - 3.2 h) post-exercise, whereas cTnI peaked later, at 4.5 h (CI: 4.2 - 4.9 h). Peak concentrations for cTnT and cTnI were 2.5 ng/L, CI: 0 - 11.2 ng/L and 2.16 ng/L, CI: 0 - 22.7 ng/L, respectively. Additionally, we did not observe a systematic effect of sex and maturational status mediating cTn responses.

Cardiac Troponin-T Release After Sport and Differences by Age, Sex, Training Type, Volume, and Intensity: A Critical Review

BACKGROUND

Postexercise release of cardiac troponin (cTn) is a well-known phenomenon, although the influence of various confounders remains unclear. The aim of this critical review was to analyze the postexercise release of cTn according to age, sex, different types of sport, exercise intensity and duration, and training level.

DATA SOURCES

A literature search was performed within the National Library of Medicine using the following keywords: cTn, peak, release, and exercise. The search was further refined by adding the keywords athletes, children/adolescents, and sport.

MAIN RESULTS

For final analysis, 52 studies were included: 43 adult studies, 4 pediatric studies, and 5 with a mixed population of adults and children. Several studies have investigated the kinetics of cTn response after exercise with different biomarkers. The current evidence suggests that sport intensity and duration have significant effects on postexercise cTn elevation, whereas the influence of the type of sport, age, and sex have been not completely defined yet. Most data were obtained during endurance races, whereas evidence is limited (or almost absent), particularly for mixed sports. Data on young adults and professional athletes are limited. Finally, studies on women are extremely limited, and those for non-White are absent.

CONCLUSIONS

Postexercise release of cTn can be observed both in young and master athletes and usually represents a physiological phenomenon; however, more rarely, it may unmask a subclinical cardiac disease. The influence of different confounders (age, sex, sport type/intensity/duration, and training level) should be better clarified to establish individualized ranges of normality for postexercise cTn elevation.

Effects of curtailed sleep on cardiac stress biomarkers following high-intensity exercise

Objective

Physical exercise—especially at high intensity—is known to impose cardiac stress, as mirrored by, e.g., increased blood levels of cardiac stress biomarkers such as cardiac Troponin T (cTnT) and NT-proBNP. We examined healthy young participants to determine whether a few nights of short sleep duration alter the effects of acute exercise on these blood biomarkers.

Methods

Sixteen men participated in a randomized order in a crossover design, comprising three consecutive nights of a) normal sleep duration (NS, 8.5 h of sleep/night) and b) sleep restriction (SR, 4.25 h of sleep/night). Blood was repeatedly sampled for determination of NT-proBNP and cTnT serum levels before and after a high-intensity exercise protocol (i.e., 75% VO₂^maxReserve cycling on an ergometer).

Results

Under pre-exercise sedentary conditions, blood levels of cTnT and NT-proBNP did not significantly differ between the sleep conditions (P > 0.10). However, in response to exercise, the surge of circulating cTnT was significantly greater following SR than NS (+37–38% at 120–240 min post-exercise, P ≤ 0.05). While blood levels of NT-proBNP rose significantly in response to exercise, they did not differ between the sleep conditions.

Conclusion

Recurrent sleep restriction may increase the cardiac stress response to acute high-intensity exercise in healthy young individuals. However, our findings must be further confirmed in women, older subjects and in patients with a history of heart disease.

•

Chronic sleep curtailment increases the risk of cardiovascular disease.

•

Here, we examined whether exercise-induced cardiac strain in healthy young adults is altered by sleep curtailment.

•

Blood levels of the cardiac stress marker troponin were higher after exercise under conditions of recurrent sleep restriction.

•

Sleep restriction may increase exercise-induced cardiac strain in adults.

High-sensitivity cardiac troponins in pediatric population

Apparently healthy children often complain of chest pain, especially after physical exercise. Cardiac biomarker levels are often measured, but the clinical relevance of these assays in children is still debated, even when a cardiac disease is present. Coronary artery disease is exceedingly rare in children, but elevated circulating levels of cardiac troponin I (cTnI) and T (cTnT) in an acute setting may help detect heart failure due to an unknown cardiac disorder, or worsening heart failure, particularly in combination with other biomarkers such as B-type natriuretic peptides. However, the interpretation of biomarkers is often challenging, especially when institutions transition from conventional cTn assays to high-sensitivity (hs-cTn) methods, as well demonstrated in the emergency setting for adult patients. From a clinical perspective, the lack of established reference values in the pediatric age is the main problem limiting the use of hs-cTn methods for the diagnosis and managements of cardiac diseases in infants, children and adolescents. This review aims to discuss the possibility to use hs-cTnI and hs-cTnT to detect cardiac disease and to explore age-related differences in biomarker levels in the pediatric age. We start from some analytical and pathophysiological considerations related to hs-cTn assays. Then, after a systematic literature search, we discuss the current evidence and possible limitations of hs-cTn assay as indicators of cardiac disease in the most frequently cardiac disease in pediatric setting.

Exercise training and high-sensitivity cardiac troponin T in patients with heart failure with reduced ejection fraction

AIMS

Whether an exercise training intervention is associated with reduction in long-term high-sensitivity cardiac troponin T (hs-cTnT) concentration (a biomarker of subclinical myocardial injury) in patients with heart failure with reduced ejection fraction (HFrEF) is unknown. The aims were to determine (i) the effect of a 12 week endurance exercise training intervention with different training intensities on hs-cTnT in stable patients with HFrEF (left ventricular ejection fraction ≤ 35%) and (ii) associations between hs-cTnT and peak oxygen uptake (VO2peak ).

METHODS AND RESULTS

In this sub-study of the SMARTEX-HF trial originally including 261 patients from nine European centres, 213 eligible patients were included after withdrawals and appropriate exclusions [19% women, mean age 61.2 years (standard deviation: 11.9)], randomized to high-intensity interval training (HIIT; n = 77), moderate continuous training (MCT; n = 63), or a recommendation of regular exercise (RRE; n = 73). Hs-cTnT measurements and clinical data acquired before (BL) and after a 12 week exercise training intervention (12 weeks) and at 1 year follow-up (1 year) were analysed using multivariable mixed models. Baseline hs-cTnT was above the 99th percentile upper reference limit of 14 ng/L in 35 (48%), 35 (56%), and 49 (64%) patients in the RRE, MCT, and HIIT groups, respectively. Median hs-cTnT was 16 ng/L at BL, 14 ng/L at 12 weeks, and 14 ng/L at 1 year. Hs-cTnT was statistically significantly reduced at 12 weeks in a model adjusted for randomization group, centre and VO2peak , and after further adjustment in the final model that also included age, sex, creatinine concentrations, N-terminal pro-brain natriuretic peptide, smoking, and heart failure treatment. The mean reduction from BL to 12 weeks in the final model was 1.1 ng/L (95% confidence interval: 1.0-1.2 ng/L, P < 0.001), and the reduction was maintained at 1 year with a mean reduction from BL to 1 year of 1.1 ng/L (95% confidence interval: 1.0-1.1 ng/L, P = 0.025). Randomization group was not associated with hs-cTnT at any time point (overall test: P = 0.20, MCT vs. RRE: P = 0.81, HIIT vs. RRE: P = 0.095, interaction time × randomization group: P = 0.88). Independent of time point, higher VO2peak correlated with lower hs-cTnT (mean reduction over all time points: 0.2 ng/L per increasing mL·kg-1 ·min-1 , P = 0.002), without between-group differences (P = 0.19).

CONCLUSIONS

In patients with stable HFrEF, a 12 week exercise intervention was associated with reduced hs-cTnT in all groups when adjusted for clinical variables. Higher VO2peak correlated with lower hs-cTnT, suggesting a positive long-term effect of increasing VO2peak on subclinical myocardial injury in HFrEF, independent of training programme.

Determination of the pathways of potential muscle damage and regeneration in response to acute and long-term swimming exercise in mice

The objective of the current study was examining early and late (3, 24 h) responses to acute, chronic swimming exercise as muscle damage and regeneration in gastrocnemius-soleus muscle complexes. We also aimed to reveal the signaling pathways involved. 8-12 weeks old mice were grouped as control, exercise. Exercising groups were firstly divided into two as acute and chronic, later every group was again divided in terms of time (3, 24 h) passed from the last exercise session until exsanguination. Acute exercise groups swam 30 min, while chronic swimming groups exercised 30 min/day, 5 days/week, 6 weeks. Histological investigations were performed to determine muscle damage and regeneration. Whole-genome expression analysis was applied to total RNA samples. Microarray data was confirmed by quantitative real-time PCR. Exercising mice muscle revealed enhanced damage, leukocyte infiltration. Increments in acute and chronic 3 h groups were statistically significant. Car3, Neb, Obscn, Ttn, Igfbp5, Igfbp7, Gsk3β, and Usp2 were down-regulated in muscles of swimming mice. The exercise-induced signaling pathways involved in muscle damage and regeneration were drawn. Our findings demonstrate that swimming induces muscle damage. Samples were obtained at 3 and 24 h following exercise, this time duration seems not sufficient for the development of myofibrillogenesis.

Exercise-Induced Release of Cardiac Troponins in Adolescent vs. Adult Swimmers

To examine the exercise-induced release of cardiac troponin T (cTnT) in adolescent and adult swimmers. Thirty-two trained male (18 adolescents, 14 adults) swam at maximal pace in a 45 min distance trial, and blood samples were drawn before, immediately and 3 h after exercise for subsequent cTnT analysis and comparison. Having comparable training experience and baseline values of cTnT (p = 0.78 and p = 0.13), adults exercised at lower absolute and relative intensity (p < 0.001 and p < 0.001, respectively), but presented higher immediate cTnT after exercise than adolescents (p < 0.001). Despite that, peak concentrations were observed at 3 h post exercise and peak elevations were comparable between groups (p = 0.074). Fourteen (44%) apparently healthy subjects exceeded the cutoff value for myocardial infarction (MI). Adolescents presented a delayed elevation of cTnT compared with adults, but achieved similar peak values.

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.

Effect of Long-Duration Adventure Races on Cardiac Damage Biomarker Release and Muscular Function in Young Athletes

The aim of the present study was to examine the effect of 1- and 2-day adventure races on cardiac muscle damage and skeletal muscle soreness and function in young athletes. Twelve male trained adolescents (14-15 years) completed both 1-day (48.2 km) and 2-day (66.0 km) races that included trail running, mountain biking, kayaking, and in-line skating separated by 10 weeks. Myocardial damage biomarker concentrations (cTnI and CK-MB), maximal voluntary isometric contraction (MVIC) torque, perceived knee extensor (KE) muscle soreness (PMS), and drop and squat jump heights were measured before and after each race. Heart rate was also monitored throughout. Mean heart rate (% cardiac reserve) was higher during the 1-day (66.6 ± 6.4%) than 2-day (62.6 ± 7.8%, p = 0.038) race. The amplitude of cardiac damage biomarker release was also higher following the 1-day than the 2-day race (peak cTnI: 0.14 vs. 0.03 ng/mL, p = 0.045; peak CK-MB: 20.30 vs. 11.98 ng/mL, p = 0.020). However, cardiac biomarker concentrations returned to baseline at 24-48 h post-exercise, except for CK-MB after the 2-day race (p = 0.017). Eight and three participants exceeded the cTnI cut-off for myocardial injury in 1- and 2-day races, respectively, but none exceeded the cut-off for acute myocardial infarction. While there was a significant decrease in drop jump height (-5.9%, p = 0.003), MVIC torque and squat jump height remained unchanged after both races. PMS was increased at 24 h after both races (p < 0.001) but returned to baseline levels by 72 h post-race. In conclusion, the shorter, more intense race produced more cardiac damage, although this probably represents a standard exercise intensity-dependent response rather than pathological response. Skeletal muscle functional and soreness responses were moderate and similar between races.

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.

Duration of Elevated Heart Rate Is an Important Predictor of Exercise-Induced Troponin Elevation

Background The precise mechanisms causing cardiac troponin (cTn) increase after exercise remain to be determined. The aim of this study was to investigate the impact of heart rate (HR) on exercise-induced cTn increase by using sports watch data from a large bicycle competition. Methods and Results Participants were recruited from NEEDED (North Sea Race Endurance Exercise Study). All completed a 91-km recreational mountain bike race (North Sea Race). Clinical status, ECG, blood pressure, and blood samples were obtained 24 hours before and 3 and 24 hours after the race. Participants (n=177) were, on average, 44 years old; 31 (18%) were women. Both cTnI and cTnT increased in all individuals, reaching the highest level (of the 3 time points assessed) at 3 hours after the race (P<0.001). In multiple regression models, the duration of exercise with an HR >150 beats per minute was a significant predictor of both cTnI and cTnT, at both 3 and 24 hours after exercise. Neither mean HR nor mean HR in percentage of maximum HR was a significant predictor of the cTn response at 3 and 24 hours after exercise. Conclusions The duration of elevated HR is an important predictor of physiological exercise-induced cTn elevation. Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02166216.

Effects of Matched Intermittent and Continuous Exercise on Changes of Cardiac Biomarkers in Endurance Runners

Purpose

Endurance runners training with high-intensity intermittent exercise might experience damage to cardiac muscle. We have therefore compared changes of cardiac biomarkers after workload-matched intermittent and continuous exercise.

Methods

Twelve endurance runners [11 males, 1 female; means ± SD V.O_2max, 62.4 ± 5.4 ml kg^–1 min^–1; velocity of V.O_2max (v V.O_2max), 17.1 ± 1.4 km h^–1] completed an intermittent and continuous exercise trial in random order. Intermittent exercise consisted of running at 90% vV.O_2max for 2 min followed by 50% vV.O_2max for 2 min, repeated for 92 min. Continuous exercise was performed at 70% vV.O_2max for 92 min. Blood samples were drawn before and 0, 2, 4, 24, and 48 h after exercise for assay of various cardiac biomarkers. Changes in concentration of biomarkers were averaged for the comparison of intermittent with continuous exercise after adjustment for baseline concentration and exercise intensity expressed as percent of heart-rate reserve (%HRR); magnitudes were assessed by standardization.

Results

There were moderate and large increases in high-sensitivity cardiac troponin-I and -T respectively following exercise. The differences between the increases adjusted to the mean intensity of 78 %HRR were trivial, but at 85 %HRR the increases for cardiac troponin-I and -T were moderately higher for intermittent compared with continuous exercise (factor difference, ×/÷90% confidence limits: 3.4, ×/÷1.9 and 2.1, ×/÷1.8 respectively). Differences in the changes in other cardiac biomarkers were trivial.

Conclusion

Prolonged intermittent exercise is potentially more damaging to cardiac muscle than continuous exercise of the same average running speed at higher average heart rates in endurance runners.

Effect of Training Load on Post-Exercise Cardiac Troponin T Elevations in Young Soccer Players

Training load (TL) metrics are usually assessed to estimate the individual, physiological and psychological, acute, and adaptive responses to training. Cardiac troponins (cTn) reflect myocardial damage and are routinely analyzed for the clinical diagnosis of myocardial injury. The association between TL and post-exercise cTn elevations is scarcely investigated in young athletes, especially after playing common team sports such as soccer. The objective of this study was to assess the relationship between TL measurements during a small-sided soccer game and the subsequent increase in cTn in young players. Twenty male soccer players (age 11.9 ± 2 years, height 151 ± 13 cm, weight 43 ± 13 kg) were monitored during a 5 × 5 small-sided game and had blood samples drawn before, immediately after, and 3 h after exercise for a posterior analysis of high-sensitivity cardiac troponin T (hs-cTnT). Internal, external, and mixed metrics of TL were obtained from the rating of perceived exertion (RPE), heart rate (HR), and GPS player tracking. The results show that the concentration of hs-cTnT peaked at 3 h post-exercise in all participants. The magnitude of hs-cTnT elevation was mainly explained by the exercise duration in the maximal heart rate zone (Maximum Probability of Effect (MPE) = 92.5%), time in the high-speed zone (MPE = 90.4 %), and distance in the high-speed zone (MPE = 90.45%). Our results support the idea that common metrics of TL in soccer, easily obtained using player tracking systems, are strongly associated with the release of hs-cTnT in children and adolescents.

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.

Changes of cardiac biomarkers after ultradistance and standard-distance triathlon

Triathlon is becoming more popular sport due to recognition of the positive effects of triathlon. Generally, participants in these strenuous activities are well considered as healthy individuals pursuing a healthy lifestyle. However, there is still controversy on the beneficial effects of prolonged exercise training and endurance sport events. The duration of exercise required to elicit cardiac dysfunction and the mechanisms underlying this phenomenon have not been fully elucidated. There are only limited data in literature for exercise-induced changes of cardiac and muscle damage biomarkers in athletes participating in different triathlon distances. Monitoring cardiac and muscle damage biomarkers in triathletes participating in different triathlon distances will help researchers, coaches, and athletes better understand how to design training cycles minimizing overtraining and injury risk. Therefore, the purpose of the present study was to examine for evidence of blood biomarkers during triathlon events of two different distances such as standard- and ultradistance triathlon in male triathletes. The results of the present study showed that ultradistance showed greater muscle damage markers such as creatine kinase, myoglobin and lactate dehydrogenase than standard-distance. We also found that the distance of triathlon did not lead to an increase of troponin T in male triathletes.

Cardiac Biomarker Release After Exercise in Healthy Children and Adolescents: A Systematic Review and Meta-Analysis

PURPOSE

The authors evaluated the impact of acute exercise and 24-hour recovery on serum concentration of cardiac troponins T and I (cTnT and cTnI) and N-terminal fragment of the prohormone brain natriuretic peptide (NT-proBNP) in healthy children and adolescents. The authors also determined the proportion of participants exceeding the upper reference limits and acute myocardial infarction cutoff for each assay.

METHOD

Web of Science, SPORTDiscus, MEDLINE, ScienceDirect, and Scopus databases were systematically searched up to November 2017. Studies were screened and quality-assessed; the data was systematically extracted and analyzed.

RESULTS

From 751 studies initially identified, 14 met the inclusion criteria for data extraction. All 3 biomarkers were increased significantly after exercise. A decrease from postexercise to 24 hours was noted in cTnT and cTnI, although this decrease was only statistically significant for cTnT. The upper reference limit was exceeded by 76% of participants for cTnT, a 51% for cTnI, and a 13% for NT-proBNP. Furthermore, the cutoff value for acute myocardial infarction was exceeded by 39% for cTnT and a 11% for cTnI. Postexercise peak values of cTnT were associated with duration and intensity (Q₍₃₎ = 28.3, P < .001) while NT-proBNP peak values were associated with duration (Q₍₂₎ = 11.9, P = .003).

CONCLUSION

Exercise results in the appearance of elevated levels of cTnT, cTnI, and NT-proBNP in children and adolescents. Postexercise elevations of cTnT and NT-proBNP are associated with exercise duration and intensity.

The cTnT response to acute exercise at the onset of an endurance training program: evidence of exercise preconditioning?

PURPOSE

Exercise induces a cardioprotective effect referred to as "preconditioning". Whether the preconditioning impacts upon the cardiac troponin T (cTnT) response to subsequent exercise bouts is unclear. This study investigated the effects of an initial exercise bout, a second exercise bout 48 h later, as well as subsequent exercise every 48 h for 4 days or a single identical exercise bout after 8 days of inactivity gap on cTnT response to acute exercise.

METHODS

Twenty-eight sedentary overweight young women were randomly assigned to either six bouts of exercise each separated by 48 h or three bouts of exercise with 48 h between the first two bouts and 8 days between the second and third bouts. All exercise bouts were identical (60% [Formula: see text], 200 kJ) and the total testing period (10 days) was the same for both groups. cTnT was assessed before and after the 1st, 2nd, and final exercise bouts.

RESULTS

cTnT increased (129%, P < 0.05) after the first bout of exercise in both groups (peak post-exercise cTnT, median [range], ng l^-1: 3.43[< 3.00-27.26]) with no between-group differences in the response. The second exercise bout had no significant (P > 0.05) effect on post-exercise cTnT (< 3.00[< 3.00-21.96]). The final exercise bout resulted in an increase (190%, P < 0.05) in cTnT (4.35[< 3.00-13.05]) in both groups.

CONCLUSIONS

A single bout exercise resulted in a temporary blunting of cTnT response to acute exercise 48 h later. The effect of exercise preconditioning was not preserved, regardless of whether followed by repeated exercise every 48 h or a cessation of exercise for 8 days.

The impact of high-intensity interval training on the cTnT response to acute exercise in sedentary obese young women

AIMS

This study characterized (a) the cardiac troponin T (cTnT) response to three forms of acute high-intensity interval exercise (HIE), and (b) the impact of 12 weeks of HIE training on the cTnT response to acute exercise in sedentary obese young women.

METHODS

Thirty-six sedentary women were randomized to traditional HIE training (repeated 4-minute cycling at 90% V ˙ O_2max interspersed with 3-minute rest, 200 kJ/session), work-equivalent sprint interval exercise (SIE) training (repeated 1-minute cycling at 120% V ˙ O_2max interspersed with 1.5-minute rest) or repeated-sprint exercise (RSE) training (40 × 6-second all-out sprints interspersed with 9-second rest) group. cTnT was assessed using a high-sensitivity assay before and immediately, 3 and 4 hours after the 1st (PRE), 6th (EARLY), 20th (MID), and 44th (END) training session, respectively.

RESULTS

cTnT was elevated (P < 0.05) after all forms of acute interval exercise at the PRE and EARLY assessment with cTnT response higher (P < 0.05) after HIE (307%) and SIE (318%) than RSE (142%) at the PRE assessment. All forms of acute interval exercise at MID and END had no effect on the cohort cTnT concentration post-exercise (all P > 0.05).

CONCLUSION

For sedentary obese young women, both HIE and SIE, matched for total work, induced a similar elevation in cTnT after acute exercise with a smaller rise observed after RSE. By the 44th training session, almost no post-exercise cTnT elevation was observed in all three groups. Such information is relevant for clinicians as it could improve medical decisionmaking.

Post marathon cardiac troponin T is associated with relative exercise intensity

OBJECTIVES

This study aimed to investigate whether measures of cardiopulmonary fitness and relative exercise intensity were associated with high sensitivity cardiac troponin T (cTnT) rise after a road marathon.

METHODS

Fifty-two marathon runners (age 39±11 years, body mass 76.2±12.9kg, height 1.74±0.09m) attended the laboratory between 2 and 3 weeks prior to attempting the Brighton Marathon, UK. Running economy at 10kmh^-1 (RE10) and race pace (RERP), ventilatory threshold (VT) and VO₂max tests were completed. CTnT was measured within 48h prior to the marathon and within 10min of completing the marathon, using a high sensitivity assay. Heart rates (HR) were recorded throughout the marathon.

RESULTS

Runners demonstrated a significant increase in cTnT over the marathon (pre-race 5.60±3.27ngL^-1, post-race 74.52±30.39ngL^-1, p<0.001). Markers of endurance performance such as running economy (10kmh^-1 223±18mlkg^-1km^-1; race pace 225±22mlkg^-1km^-1), VT (38.5±6.4mlkg^-1min^-1) and V˙O₂max (50.9±7.7mlkg^-1min^-1) were not associated with post-race cTnT. Runners exercise intensity correlated with post-race cTnT (mean HR %VT 104±5%, r=0.50; peak HR %VT 118±8%, r=0.68; peak HR %V˙O₂max 96±6, r=0.60, p<0.05) and was different between the low, medium and high cTnT groups (p<0.05).

CONCLUSIONS

CTnT increases above reference limits during a marathon. Magnitude of cTnT rise is related to exercise intensity relative to ventilatory threshold and V˙O₂max, but not individuals' absolute cardiopulmonary fitness, training state or running history.

Impact of high-intensity interval training and moderate-intensity continuous training on resting and postexercise cardiac troponin T concentration

NEW FINDINGS

What is the central question of this study? Does exercise training impact resting and postexercise cardiac troponin T (cTnT) concentration? What is the main finding and its importance? This randomized controlled intervention study demonstrated that 12 weeks of either high-intensity interval training or moderate-intensity continuous training largely abolished the exercise-induced elevation in cTnT when exercise was performed at the same absolute intensity. There was no impact of training on resting cTnT or postexercise appearance of cTnT when exercise was performed at the same relative intensity. These findings provide new information that might help clinicians with decision-making in relationship to basal and postexercise values of cTnT in individuals with different training status.

ABSTRACT

We evaluated the influence of 12 weeks of high-intensity interval training [HIIT; repeated 4 min cycling at 90% of maximal oxygen uptake (V̇O2max) interspersed with 3 min rest, 200-300 kJ per session, 3 or 4 days each week] and work-equivalent moderate-intensity continuous training (MICT; continuous cycling at 60% V̇O2max) on resting cardiac troponin T (cTnT) and the appearance of exercise-induced cTnT. Forty-eight sedentary obese young women were randomly assigned to HIIT, MICT or a control group. The V̇O2max and body composition were measured before and after training. At baseline, cTnT was assessed using a high-sensitivity assay at rest and immediately, 2 and 4 h after 45 min cycling at 60% V̇O2max. After a 12 week training period, cTnT was assessed before and after 45 min cycling at the same relative and absolute intensities as before training. Training led to higher V̇O2max and lower fat mass in both HIIT and MICT groups (all P < 0.05). Before training, cTnT was significantly elevated in all three groups (by 35-118%, all P < 0.05) with acute exercise. After training, both resting and postexercise cTnT concentrations (same relative intensity) were similar to pretraining values. In contrast, postexercise cTnT (same absolute intensity, which represented a smaller exercise stimulus) was not elevated from rest in both HIIT and MICT groups. In conclusion, 12 weeks of either HIIT or MICT largely abolished the postexercise elevation of cTnT concentration when exercise was performed at the same absolute intensity. There was, however, no impact of training on resting cTnT or postexercise appearance of cTnT for exercise performed at the same relative intensity.

High-sensitivity cardiac troponin T release after a single bout of high-intensity interval exercise in experienced marathon runners

OBJECTIVE

The purpose of this study was to investigate the effects of a single bout of high-intensity interval exercise (HIIE) on high-sensitivity cardiac troponin T (hs-cTnT) release and to explore the potential influencing factors.

METHODS

Twenty-one experienced marathon runners completed HIIE on treadmill. Each bout of HIIE included a hard run (15.8 ± 1.3 km·h-1) at 90% vVO2max for 2 min followed by an easy run (8.8 ± 0.7 km·h-1) at 50% vVO2max for 2 min performed 23 times within 92 min. Heart rate (HR) was recorded every 2 min during HIIE. The hs-cTnT level was measured before (pre), immediately after (0 h), and at 4 and 24 h after exercise.

RESULTS

The hs-cTnT level was elevated at 0 h, peaked at 4 h, and had not returned to the baseline value at 24 h after exercise. The response of hs-cTnT at 4 h was positively related to exercise HR. Subjects with a greater increase in hs-cTnT level had a higher exercise HR under fixed exercise intensity.

CONCLUSION

HIIE at 90% vVO2max interspersed with 50% vVO2max for recovery can elicit hs-cTnT elevation. HR is a good predictor of exercise-induced cardiac troponin (cTn) release under fixed exercise intensity. Further study should consider to correct for HR when constructing impact factors contributing to exercise-induced cTn release.

Cardiac Biomarker Release after Endurance Exercise in Male and Female Adults and Adolescents

OBJECTIVES

To compare the responses of high-sensitivity cardiac troponin T (hs-cTnT) and NH₂-terminal probrain natriuretic peptide (NT-proBNP) after 60 minutes of swimming in male and female adults and adolescents with different pubertal status.

STUDY DESIGN

Adolescent swimmers (25 male and 25 female) and adult swimmers (7 male and 9 female) participated in a 60-minute maximal swimming test with serial assessment of hs-cTnT and NT-proBNP at rest, immediately postexercise, and at 1, 3, 6, 12, and 24 hours postexercise. Adolescents were classified according to pubertal status: Tanner stages 3 (n = 14), 4 (n = 22), and 5 (n = 14).

RESULTS

Exercise resulted in an increase in both biomarkers. hs-cTnT responses to exercise were similar in adolescents with different pubertal status and adults, although there was substantial individual variability in peak hs-cTnT, with the upper reference limit exceeding in 62% of the participants. Postexercise kinetics for hs-cTnT were largely consistent across all groups with a return to near baseline levels 24 hours postexercise. The male participants showed higher values of hs-cTnT at baseline and postexercise. All groups had similar NT-proBNP responses to acute exercise and recovery. One swimmer exceeded the upper reference limit for NT-proBNP.

CONCLUSIONS

An exercise-associated increase in hs-cTnT and NT-proBNP occurred in response to a 60-minute maximal swimming test that was independent of pubertal status/adolescent vs adults. The present data also suggests that baseline and postexercise hs-cTnT values are higher in male compared with female, with no sex differences in NT-proBNP values.

Blood biomarkers in male and female participants after an Ironman-distance triathlon

Background

While overall physical activity is clearly associated with a better short-term and long-term health, prolonged strenuous physical activity may result in a rise in acute levels of blood-biomarkers used in clinical practice for diagnosis of various conditions or diseases. In this study, we explored the acute effects of a full Ironman-distance triathlon on biomarkers related to heart-, liver-, kidney- and skeletal muscle damage immediately post-race and after one week’s rest. We also examined if sex, age, finishing time and body composition influenced the post-race values of the biomarkers.

Methods

A sample of 30 subjects was recruited (50% women) to the study. The subjects were evaluated for body composition and blood samples were taken at three occasions, before the race (T1), immediately after (T2) and one week after the race (T3). Linear regression models were fitted to analyse the independent contribution of sex and finishing time controlled for weight, body fat percentage and age, on the biomarkers at the termination of the race (T2). Linear mixed models were fitted to examine if the biomarkers differed between the sexes over time (T1-T3).

Results

Being male was a significant predictor of higher post-race (T2) levels of myoglobin, CK, and creatinine levels and body weight was negatively associated with myoglobin. In general, the models were unable to explain the variation of the dependent variables. In the linear mixed models, an interaction between time (T1-T3) and sex was seen for myoglobin and creatinine, in which women had a less pronounced response to the race.

Conclusion

Overall women appear to tolerate the effects of prolonged strenuous physical activity better than men as illustrated by their lower values of the biomarkers both post-race as well as during recovery.

Acute effect of intermittent and continuous aerobic exercise on release of cardiac troponin T in sedentary men

BACKGROUND

Studies have shown that acute exercise can increase serum concentrations of cardiac biomarkers, including cardiac troponin T (cTnT). We investigated the acute effects of intermittent (IE) and continuous (CE) exercise at the same cardiac workload on myocardial necrosis biomarkers in sedentary men.

METHODS

Eleven sedentary healthy men aged 22.3±1.9years completed the study. The subjects were divided into two groups and performed, in random order, IE (intensity alternating between 50% (2min) and 80% (1min) HRreserve) or CE (60% HRreserve). The study was designed as a single-blinded randomised crossover trial performed on two distinct experimental days separated by a 1-week washout period. Each session consisted of 40min of aerobic exercise, either IE or CE, on a treadmill. Blood samples were taken before (PRE), immediately after (POST) and 1h after (POST-1) each exercise session.

RESULTS

hs-cTnT significantly increased immediately after exercise in both protocols and remained elevated at POST-1 (P<0.05). There was no significant difference between POST and POST-1 values(P>0.05). Neither CE nor IE caused any significant change in CK-MB (P>0.05). The results also showed that HR and RPP increased significantly following both exercise protocols (P=0.001).

CONCLUSIONS

In summary, both CE and IE results in increased serum concentrations of hs-cTnT in sedentary men. However, this increase does not seem to be caused by the irreversible death of cardiomyocytes. CE resulted in a greater hs-cTnT concentration than IE.

The 99th percentile of reference population for cTnI and cTnT assay: methodology, pathophysiology and clinical implications

According to recent international guidelines, including the 2012 Third Universal Definiton of Myocardial Infarction by the Joint ESC/ACCF/AHA/WHF Task Force, an increase in cardiac troponin (cTn) levels over the 99th percentile upper reference limit (99th URL) should be considered clinically relevant, this cut-off being measured with an imprecision ≤10 CV%. In theory 99th URL values strongly depend not only on demographic and physiological variables (i.e. criteria for considering the reference population “healthy”), but also on the analytical performance of cTn methods and mathematical algorithms used for the calculation. The aim of the present article was therefore to review the methodological and pathophysiological factors affecting the evaluation and calculation of the 99th URL for cTn assay. The critical analysis made showed that no uniform procedure is followed, and nor have experts or regulatory bodies provided uniform guidelines for researchers or cTn assays manufacturers as an aid in “their quest to define normality”. In particular, little attention has been paid to the way in which a healthy reference population is to be selected, or the criteria for calculating the 99th URL value for cTn assays, thus highlighting the need for international recommendations not only for demographic and physiological variables criteria for defining a healthy reference population, but also for calculating mathematical algorithms for establishing/calculating clinical decision values. An expert consensus group, comprising laboratory and clinical scientists, biomedical statisticians, industrial and regulatory representatives, should be responsible for drawing up these guidelines.

Evaluation of Serial High Sensitivity Troponin T Levels in Individuals Without Overt Coronary Heart Disease Following Exercise Stress Testing

BACKGROUND

Detectable levels of high sensitivity (cardiac) troponin T (HsTnT), occur in the majority of patients with stable coronary heart disease (CHD), and often in 'healthy' individuals. Extreme physical activity may lead to marked elevations in creatine kinase MB and TnT levels. However, whether HsTnT elevations occur commonly after exercise stress testing (EST), and if so, whether this has clinical significance, needs clarification.

METHODS

To determine whether HsTnT levels become elevated after EST (Bruce protocol) to ≥95% of predicted maximum heart rate in presumed healthy subjects without overt CHD, we assayed HsTnT levels for ∼5h post-EST in 105 subjects (median age 37 years).

RESULTS

Pre-EST HsTnT levels <5 ng/L were present in 31/32 (97%) of females and 52/74 (70%) of males. Post-EST, 13 (12%) subjects developed HsTnT levels >14 ng/L, with troponin elevation occurring at least three hours post-EST. Additionally, a detectable ≥ 50% increase in HsTnT levels (4.9→9ng/L) occurred in 28 (27%) of subjects who during EST achieved ≥ 95% of their predicted target heart rate. The median age of the subjects with HsTnT elevations to > 14ng/L post-EST was higher than those without such elevation (42 and 36 years respectively; p=0.038). At a median follow-up of 13 months no adverse events were recorded.

CONCLUSION

The current study demonstrates that detectable elevations occur in HsTnT post-EST in 'healthy' subjects without overt CHD. Future studies should evaluate the clinical significance of detectable elevations in post-EST HsTnT with long-term follow-up for adverse cardiac events.

Cardiac troponin I release after a basketball match in elite, amateur and junior players

BACKGROUND

Available scientific data related to cardiac troponin I (cTnI) release after intermittent exercise is limited. It is also of interest to determine what personal or environmental factors mediate the exercise-induced release of cTnI. This study had two objectives: 1) to examine the individual release of cTnI to a basketball match; and 2) to establish the influence of athlete status as well as biological age on cTnI release.

METHODS

Thirty-six basketball players (12 adult elite [PBA]: 27.3±4.1 years, 12 adult amateur [ABA]: 29.6±2.9 years, and 12 junior elite [JBA]: 16.6±0.9 years) participated in a simulated basketball match with serial assessment of cTnI at rest, immediately post- and at 1, 3, 6, 12, and 24 h post-exercise.

RESULTS

The basketball match increased cTnI levels (pre: median [range]; 0.006 [0.001-0.026]; peak post: 0.024 [0.004-0.244] μg/L; p=0.000), with substantial individual variability in peak values. PBA and JBA players showed higher baseline and post-exercise cTnI values than ABA (all p<0.05). Peak cTnI exceeded the upper reference limit (URL) in the 26% of players (3 PBA; 6 JBA).

CONCLUSIONS

The current results suggest that intermittent exercise can promote the appearance of cTnI and that this is potentially mediated by athlete status.

The impact of remote ischemic preconditioning on cardiac biomarker and functional response to endurance exercise

Remote ischemic preconditioning (RIPC; repeated short reversible periods of ischemia) protects the heart against subsequent ischemic injury. We explored whether RIPC can attenuate post-exercise changes in cardiac troponin T (cTnT) and cardiac function in healthy individuals. In a randomized, crossover design, 14 participants completed 1-h cycling time trials (TT) on two separate visits; preceded by RIPC (arms/legs, 4 × 5-min 220 mmHg), or SHAM-RIPC (20 mmHg). Venous blood was sampled before and 0-, 1-, and 3-h post-exercise to assess high sensitivity (hs-)cTnT and brain natriuretic peptide (NT-proBNP). Echocardiograms were performed at the same time points to assess left and right ventricular systolic (ejection fraction; EF and right ventricular fractional area change; RVFAC, respectively) and diastolic (early transmitral flow velocities; E) function. Baseline hs-cTnT was not different between RIPC and SHAM. Post-exercise hs-cTnT levels were consistently lower following RIPC (18 ± 3 vs 21 ± 3; 19 ± 3 vs 23 ± 3; and 20 ± 2 vs 25 ± 2 ng/L at 0, 1 and 3-h post-exercise, respectively; P < 0.05). There was no main effect of time, trial, or interaction for NT-proBNP and left ventricular EF or RVFAC (all P < 0.05). A main effect of time was evident for E which transiently declined immediately after exercise to a similar level in both trials (0.85 ± 0.04 vs 0.74 ± 0.04 m/s, respectively; P < 0.05). In summary, RIPC was associated with lower hs-cTnT levels after exercise but there was no independent effect of RIPC for NT-proBNP or LV systolic and diastolic function. The lower hs-cTnT levels after RIPC suggests that further research should evaluate the role of ischemia in exercise-induced elevation in hs-cTnT.

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.

Exercise Dose in Clinical Practice

There is wide variability in the physical activity patterns of the patients in contemporary clinical cardiovascular practice. This review is designed to address the impact of exercise dose on key cardiovascular risk factors and on mortality. We begin by examining the body of literature that supports a dose-response relationship between exercise and cardiovascular disease risk factors, including plasma lipids, hypertension, diabetes mellitus, and obesity. We next explore the relationship between exercise dose and mortality by reviewing the relevant epidemiological literature underlying current physical activity guideline recommendations. We then expand this discussion to critically examine recent data pertaining to the impact of exercise dose at the lowest and highest ends of the spectrum. Finally, we provide a framework for how the key concepts of exercise dose can be integrated into clinical practice.

Cardiac troponin T and echocardiographic dimensions after repeated sprint vs. moderate intensity continuous exercise in healthy young males

Regular physical exercise can positively influence cardiac function; however, investigations have shown an increase of myocardial damage biomarkers after acute prolonged endurance exercises. We investigated the effect of repeated sprint vs. moderate long duration exercise on markers of myocardial necrosis, as well as cardiac dimensions and functions. Thirteen healthy males performed two different running sessions (randomized, single blinded cross-over design): 60 minutes moderate intensity continuous training (MCT, at 70% of peak heart rate (HR_peak)) and two series of 12 × 30-second sprints with set recovery periods in-between (RST, at 90% HR_peak). Venous blood samples for cardiac troponin T (cTnT), creatine kinase (CK) and MB isoenzyme (CK-MB) were taken 1 and 4 hours after exercise sessions. After each session electrocardiographic (ECG) and transthoracic echocardiographic (TTE) data were recorded. Results showed that all variables - average heart rate, serum lactate concentration during RST, subjective exertion and cTnT after RST - were significantly higher compared to MCT. CK and CK-MB significantly increased regardless of exercise protocol, while ECG and TTE indicated normal cardiac function. Our results provide evidence that RST contributes significantly to cTnT and CK release. This biomarker increase seems to reflect a physiological rather than a pathological phenomenon in healthy, exercising subjects.

Individual variability in cardiac biomarker release after 30 min of high-intensity rowing in elite and amateur athletes

This study had two objectives: (i) to examine individual variation in the pattern of cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) release in response to high-intensity rowing exercise, and (ii) to establish whether individual heterogeneity in biomarker appearance was influenced by athletic status (elite vs. amateur). We examined cTnI and NT-proBNP in 18 elite and 14 amateur rowers before and 5 min, 1, 3, 6, 12, and 24 h after a 30-min maximal rowing test. Compared with pre-exercise levels, peak postexercise cTnI (pre: 0.014 ± 0.030 μg·L–1; peak post: 0.058 ± 0.091 μg·L–1; p = 0.000) and NT-proBNP (pre: 15 ± 11 ng·L–1; peak post: 31 ± 19 ng·L–1; p = 0.000) were elevated. Substantial individual heterogeneity in peak and time-course data was noted for cTnI. Peak cTnI exceeded the upper reference limit (URL) in 9 elite and 3 amateur rowers. No rower exceeded the URL for NT-proBNP. Elite rowers had higher baseline (0.019 ± 0.038 vs. 0.008 ± 0.015 μg·L–1; p = 0.003) and peak postexercise cTnI (0.080 ± 0.115 vs. 0.030 ± 0.029 μg·L–1; p = 0.022) than amateur rowers, but the change with exercise was similar between groups. There were no significant differences in baseline and peak postexercise NT-proBNP between groups. In summary, marked individuality in the cTnI response to a short but high-intensity rowing bout was observed. Athletic status did not seem to affect the change in cardiac biomarkers in response to high-intensity exercise.

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

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

Plasma electrolyte and hematological changes after marathon running in adolescents

PURPOSE

The objective of this research is to study plasma electrolyte and hematological changes in adolescent runners completing a standard 42.2-km marathon run.

METHODS

Fifty adolescents (30 healthy males and 20 healthy females) between ages 13 and 17 yr participated in the study. The participants had to undergo a routine physical examination including ECG records. Blood was taken before the race, immediately after the race, and 24 h after the race to determine complete blood cell count and electrolyte concentration.

RESULTS

Forty-seven runners completed the race with a mean finishing time of 4 h 57 min (range: 3 h 17 min 09 s to 6 h 14 min). None of the participants experienced an adverse medical event during or after the race. Only slight changes in plasma electrolytes without any cases of hyper- or hyponatremia and a marked increase in white blood cell count were demonstrated immediately after the race. At this time, the hemoglobin concentration and hematocrit were decreased (P < 0.05), indicating an approximately 11% increase in plasma volume. Some of these changes were still present 24 h postrace. No differences were observed between sexes.

CONCLUSIONS

This is the first study evaluating plasma electrolyte and hematological changes in a relatively large sample of young runners completing a standard marathon. The presented findings indicate that well-trained and educated adolescent marathon runners are not at risk to develop clinically significant electrolyte or hematological changes.

Effects of exercise with or without blueberries in the diet on cardio-metabolic risk factors: an exploratory pilot study in healthy subjects

BACKGROUND

The improvement of insulin sensitivity by exercise has been shown to be inhibited by supplementation of vitamins acting as antioxidants.

OBJECTIVE

To examine effects of exercise with or without blueberries, containing natural antioxidants, on cardio-metabolic risk factors.

METHODS

Fifteen healthy men and 17 women, 27.6 ± 6.5 years old, were recruited, and 26 completed a randomized cross-over trial with 4 weeks of exercise by running/jogging 5 km five times/week and 4 weeks of minimal physical activity. Participants were also randomized to consume 150 g of blueberries, or not, on exercise days. Laboratory variables were measured before and after a 5 km running-race at maximal speed at the beginning and end of each period, i.e. there were four maximal running-races and eight samplings in total for each participant.

RESULTS

Insulin and triglyceride levels were reduced while HDL-cholesterol increased by exercise compared with minimal physical activity. Participants randomized to consume blueberries showed an increase in fasting glucose levels compared with controls, during the exercise period (blueberries: from 5.12 ± 0.49 mmol/l to 5.32 ± 0.29 mmol/l; controls: from 5.24 ± 0.27 mmol/l to 5.17 ± 0.23 mmol/l, P = 0.04 for difference in change). Triglyceride levels fell in the control group (from 1.1 ± 0.49 mmol/l to 0.93 ± 0.31 mmol/l, P = 0.02), while HDL-cholesterol increased in the blueberry group (from 1.51 ± 0.29 mmol/l to 1.64 ± 0.33 mmol/l, P = 0.006).

CONCLUSIONS

Ingestion of blueberries induced differential effects on cardio-metabolic risk factors, including increased levels of both fasting glucose and HDL-cholesterol. However, since it is possible that indirect effects on food intake were induced, other than consumption of blueberries, further studies are needed to confirm the findings.

Cardiac troponins in young marathon runners

Cardiac troponin increases are common in adult marathon finishers. However, data on troponin values for young marathon runners are scarce. Forty young runners (20 healthy male and 20 female) 13 to 17 years old participated in this study. Blood samples were taken before, immediately after, and 24 hours after the race for determination of cardiac troponin T (cTnT) and troponin I (cTnI). Thirty-seven runners completed the race with a mean finishing time of 4 hours 53 minutes. No participant developed an adverse medical event during or after the race. In 30 of 37 participants, levels of cTnT and/or cTnI exceeded upper reference limits of 0.01 and 0.1 ng/ml immediately after the race, and in 3 participants these levels were even higher than the reference range for acute myocardial infarction (>0.1 and >0.5 ng/ml for cTnT and cTnI, respectively). Twenty-four hours after the race no participant had troponin levels exceeding the upper reference limits. Average increases of troponin levels did not differ between sexes. In conclusion, this is the first study to show that cardiac troponin levels increase to a similar extent in male and female adolescent marathon runners as observed in adults. Rapid recovery of troponin levels after a race is indicative of a physiologic rather than a pathologic response.

The kinetics of highly sensitive cardiac troponin T release after prolonged treadmill exercise in adolescent and adult athletes

The nature and kinetics of postexercise cardiac troponin (cTn) appearance is poorly described and understood in most athlete populations. We compared the kinetics of high-sensitivity cTn T (hs-cTnT) after endurance running in training-matched adolescents and adults. Thirteen male adolescent (mean age: 14.1 ± 1.1 yr) and 13 male adult (24.0 ± 3.6 yr) runners performed a 90-min constant-load treadmill run at 95% of ventilatory threshold. Serum hs-cTnT levels were assessed preexercise, immediately postexercise, and at 1, 2, 3, 4, 5, 6, and 24 h postexercise. Serum NH2-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels were recorded preexercise and 3, 6, and 24 h postexercise. Left ventricular function was assessed preexercise, immediately postexercise, and 6 h postexercise. Peak hs-cTnT occurred at 3–4 h postexercise in all subjects, but was substantially higher ( P < 0.05) in adolescents [median (range): 211.0 (11.2–794.5) ng/l] compared with adults [median (range): 19.1 (9.7–305.6) ng/l]. Peak hs-cTnT was followed by a rapid decrease in both groups, although adolescent data had not returned to baseline at 24 h. Substantial interindividual variability was noted in peak hs-cTnT, especially in the adolescents. NT-pro-BNP was significantly elevated postexercise in both adults and adolescents and remained above baseline at 24 h in both groups. In both groups, left ventricular ejection fraction and the ratio of early-to-atrial peak Doppler flow velocities were significantly decreased immediately postexercise. Peak hs-cTnT was not related to changes in ejection fraction, ratio of early-to-atrial peak Doppler flow velocities, or NT-pro-BNP. The present data suggest that postexercise hs-cTnT elevation 1) occurred in all runners, 2) peaked 3–4 h postexercise, and 3) the peak hs-cTnT concentration after prolonged exercise was higher in adolescents than adults.

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.

Metabolic markers in sports medicine

Physical exercise induces adaptations in metabolism considered beneficial for health. Athletic performance is linked to adaptations, training, and correct nutrition in individuals with genetic traits that can facilitate such adaptations. Intense and continuous exercise, training, and competitions, however, can induce changes in the serum concentrations of numerous laboratory parameters. When these modifications, especially elevated laboratory levels, result outside the reference range, further examinations are ordered or participation in training and competition is discontinued or sports practice loses its appeal. In order to correctly interpret commonly used laboratory data, laboratory professionals and sport physicians need to know the behavior of laboratory parameters during and after practice and competition. We reviewed the literature on liver, kidney, muscle, heart, energy, and bone parameters in athletes with a view to increase the knowledge about clinical chemistry applied to sport and to stimulate studies in this field. In liver metabolism, the interpretation of serum aminotransferases concentration in athletes should consider the release of aspartate aminotransferase (AST) from muscle and of alanine aminotransferase (ALT) mainly from the liver, when bilirubin can be elevated because of continuous hemolysis, which is typical of exercise. Muscle metabolism parameters such as creatine kinase (CK) are typically increased after exercise. This parameter can be used to interpret the physiological release of CK from muscle, its altered release due to rhabdomyolysis, or incomplete recovery due to overreaching or trauma. Cardiac markers are released during exercise, and especially endurance training. Increases in these markers should not simply be interpreted as a signal of cardiac damage or wall stress but rather as a sign of regulation of myocardial adaptation. Renal function can be followed in athletes by measuring serum creatinine concentration, but it should be interpreted considering the athlete's body-mass index (BMI) and phase of the competitive season; use of cystatin C could be a reliable alternative to creatinine. Exercise and training induce adaptations in glucose metabolism which improve glucose utilization in athletes and are beneficial for reducing insulin insensitivity in nonathletes. Glucose metabolism differs slightly for different sports disciplines, as revealed in laboratory levels. Sport activities induce a blood lipid profile superior to that of sedentary subjects. There are few reports for a definitive conclusion, however. The differences between athletes and sedentary subjects are mainly due to high-density lipoprotein cholesterol (HDLC) concentrations in physically active individuals, although some differences among sport disciplines exist. The effect of sports on serum and urinary markers for bone metabolism is not univocal; further studies are needed to establish the real and effective influence of sport on bone turnover and especially to establish its beneficial effect.

The effect of prolonged physical activity performed during extreme caloric deprivation on cardiac function

BACKGROUND

Endurance exercise may induce transient cardiac dysfunction. Data regarding the effect of caloric restriction on cardiac function is limited. We studied the effect of physical activity performed during extreme caloric deprivation on cardiac function.

METHODS

Thirty-nine healthy male soldiers (mean age 20 ± 0.3 years) were studied during a field training exercise lasted 85-103 hours, with negligible food intake and unlimited water supply. Anthropometric measurements, echocardiographic examinations and blood and urine tests were performed before and after the training exercise.

RESULTS

Baseline VO(2) max was 59 ± 5.5 ml/kg/min. Participants' mean weight reduction was 5.7 ± 0.9 kg. There was an increase in plasma urea (11.6 ± 2.6 to 15.8 ± 3.8 mmol/L, p<0.001) and urine osmolarity (692 ± 212 to 1094 ± 140 mmol/kg, p<0.001) and a decrease in sodium levels (140.5 ± 1.0 to 136.6 ± 2.1 mmol/L, p<0.001) at the end of the study. Significant alterations in diastolic parameters included a decrease in mitral E wave (93.6 to 83.5 cm/s; p = 0.003), without change in E/A and E/E' ratios, and an increase in iso-volumic relaxation time (73.9 to 82.9 ms, p = 0.006). There was no change in left or right ventricular systolic function, or pulmonary arterial pressure. Brain natriuretic peptide (BNP) levels were significantly reduced post-training (median 9 to 0 pg/ml, p<0.001). There was no elevation in Troponin T or CRP levels. On multivariate analysis, BNP reduction correlated with sodium levels and weight reduction (R = 0.8, p<0.001).

CONCLUSIONS

Exposure to prolonged physical activity performed under caloric deprivation resulted in minor alterations of left ventricular diastolic function. BNP levels were significantly reduced due to negative water and sodium balance.