ABSTRACT

Introduction

Strengthening research on cardiac function risk assessment in running sports is beneficial to prevent sport-related cardiovascular injuries and sudden deaths in sports.

Objective

To study changes in cardiovascular response in athletes after long-distance running.

Methods

Changes in cardiovascular response indicators of long-distance runners before and after the five-kilometer race were monitored. Analyzed indices included heart rate, blood pressure, hemoglobin, and a cardiac function index.

Results

There were no statistically significant differences in heart rate, blood pressure, and hemoglobin levels before and after the long-distance run (P>0.05). There was no significant difference in the proportion of sinus arrhythmia before and after long-distance running (P>0.05).

Conclusion

Long-distance running did not cause abnormal changes in blood indicators. No cardiovascular discomfort or changes in the electrocardiogram, heart rate, blood pressure, hemoglobin, and cardiac function index were reported. These young men were not enlisted, despite undergoing adaptive training. In conclusion, the five-kilometer run is safe for young men in the reserve. Evidence Level II; Therapeutic Studies - Investigating the result.

Running; Cardiology; Athlete; Sports

RESUMO

Introdução

O fortalecimento da pesquisa sobre a avaliação de risco da função cardíaca nos esportes de corrida é benéfico para prevenir lesões cardiovasculares e mortes súbitas relacionadas com o esporte.

Objetivo

Estudar as alterações na resposta cardiovascular dos atletas após corridas de longa distância.

Métodos

Foram monitoradas alterações nos indicadores de resposta cardiovascular dos corredores de longa distância antes e depois da corrida de cinco quilômetros. Entre os índices analisados estão a frequência cardíaca, pressão arterial, hemoglobina e índice de função cardíaca.

Resultados

Não houve diferenças estatisticamente significativas na frequência cardíaca, pressão arterial, e níveis de hemoglobina antes e depois da corrida de longa distância (P>0.05). Não houve diferença significativa na proporção de arritmia sinusal antes e depois da corrida de longa distância (P>0.05).

Conclusão

A corrida de longa distância não causou mudanças anormais nos indicadores sanguíneos. Não foram relatados desconfortos cardiovasculares ou alterações em eletrocardiograma, ritmo cardíaco, pressão arterial, hemoglobina e índice de função cardíaca. Esses jovens não estavam alistados, apesar de passarem por treino adaptativo. Conclui-se que o treino em corridas de cinco quilômetros é seguro para homens jovens na reserva. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.

Corrida; Cardiologia; Atleta; Esportes

RESUMEN

Introducción

Reforzar la investigación sobre la evaluación del riesgo de la función cardíaca en los deportes de carrera es beneficioso para prevenir las lesiones cardiovasculares relacionadas con el deporte y las muertes súbitas en el mismo.

Objetivo

Estudiar los cambios en la respuesta cardiovascular de los atletas después de correr largas distancias.

Métodos

Se han monitorizado los cambios en los indicadores de respuesta cardiovascular de los corredores de larga distancia antes y después de la carrera de cinco kilómetros. Entre los índices analizados estaban la frecuencia cardíaca, la presión arterial, la hemoglobina y el índice de función cardíaca.

Resultados

No hubo diferencias estadísticamente significativas en la frecuencia cardíaca, la presión arterial y los niveles de hemoglobina antes y después de la carrera de larga distancia (P>0,05). No hubo diferencias significativas en la proporción de arritmia sinusal antes y después de la carrera de larga distancia (P>0,05).

Conclusión

Las carreras de larga distancia no causaron cambios anormales en los indicadores sanguíneos. No se registraron molestias cardiovasculares ni cambios en el electrocardiograma, la frecuencia cardíaca, la presión arterial, la hemoglobina y el índice de función cardíaca. Estos jóvenes no se alistaron, a pesar de que se sometieron a un entrenamiento de adaptación. Se concluye que el entrenamiento en carreras de cinco kilómetros es seguro para los jóvenes de la reserva. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Carrera; Cardiología; Atleta; Deportes

INTRODUCTION

Many colleges and universities have successively canceled 3km and 5km long-distance running and other high-volume sports in recent years. The reason is to prevent the occurrence of sudden sports deaths.¹1. Siegel AJ, Noakes TD. Aspirin to prevent sudden cardiac death in athletes with high coronary artery calcium scores. The American journal of medicine. 2019;132(2):138-41. This has caused widespread concern in society. Sudden exercise-induced death is a non-traumatic death that occurs during or immediately after exercise and occurs within 6 hours. Groups younger than 20 and 20-29 years old have a high incidence of sudden exercise-related deaths in China. Most of the sudden death athletes abroad are younger than 35 years old. The sports of sudden sports death are mainly running and military training. About 80% of sudden exercise-related deaths are sudden cardiac deaths, and the cause is closely related to exercise-related cardiovascular damage. Autopsy reports from the sports and military systems show that most of the sudden exercise deaths do not have organic heart disease. Therefore, strengthening the research on the risk assessment of cardiac function for running-based sports is beneficial to prevent sports-related cardiovascular injury and sudden sports death.²2. Lechner K, Halle M, Scherr J, Drezner JA. Exercise recommendations in athletes with coronary artery calcification. European journal of preventive cardiology. 2020;27(8):882-4. Brain natriuretic peptide (BNP) is currently the most important marker for understanding heart function. Cardiac troponin I (cTnI) has good sensitivity and specificity in detecting exercise-related myocardial injury, and it is widely used to assess this type of myocardial injury. Electrocardiogram (ECG) is the most commonly used and basic testing method for checking and evaluating heart function. This study observed the changes in blood BNP and cTnI levels and ECG of 63 young people before and after the 5km long-distance running and conducted medical observations.

METHOD

Research object

The article focuses on 63 young men who participated in a 5km long-distance race. There was no fever, diarrhea, or training injury within 2 weeks. The age ranged from 18 to 35 years old, with an average of (23.9±4.3), 17 people under 20 years old, 28 people 21-25 years old, 11 people 26-30 years old, and 7 people 31-35 years old. On the afternoon of June 15, 2020, a 5km long-distance race will be carried out according to the daily training status.

Determination of plasma BNP and serum cTnI

10 mL of venous blood was drawn for testing 10 minutes before the long-distance running and 5 minutes after the long-distance running.³3. Panhuyzen-Goedkoop NM, Wellens HJ, Verbeek AL, Jørstad HT, Smeets JR, Peters RJ. ECG criteria for the detection of high-risk cardiovascular conditions in master athletes. European journal of preventive cardiology. 2020;27(14):1529-38. We use the chemiluminescence method to measure BNP level (normal value 0-263μg/L). The level of cTnI was determined by the immunofluorescence method (normal value 0-0.4μg/L).

ECG inspection and analysis

The standard 12-lead ECG in the supine position was recorded with a 12-lead electrocardiograph 10 minutes before and 5-10 minutes after the long-distance running.⁴4. Siegel AJ. Aspirin to Reduce Risk for Sudden Cardiac Death in Athletes with Elevated C-Reactive Protein Levels. The American Journal of Medicine. 2020;133(9):1014-6. ECG measurement, diagnosis, and analysis by a dedicated person according to diagnostic criteria, including heart rate, sinus bradycardia, sinus tachycardia, sinus arrhythmia, and ST-segment depression.

Medical observation

Record the number and time of chest tightness, chest pain, palpitations, dizziness, headache, syncope, and fatigue during exercise and 1 day after exercise.

Modeling of Coronary Circulation in Heart Disease

The relationship between blood pressure and volume of the ventricle is usually used to describe the systolic function of the ventricle. The mutual capacitance E ( t ) represents myocardial elasticity when building the left ventricular analog circuit model. E ( t ) is defined as the ratio of intraventricular pressure to volume, a time-varying elastic function.⁵5. Lara B, Salinero JJ, Gallo-Salazar C, Areces F, Ruiz-Vicente D, Martinez, M et al. Elevation of cardiac troponins after endurance running competitions. Circulation. 2019;139(5):709-11. The time-varying elasticity function is mainly composed of the active elasticity E ( t ) and the passive elasticity E _p of the left ventricle. The active elasticity E _a ( t ) of the left ventricle can be obtained by the following equation according to the work of Suga et al.:

Time-varying elastic function:

In the above formulas, t _n is the normalized time. T _cycle is the cardiac cycle. E _n ( t _n ) is the normalization function of E _a ( t ). E _max is the maximum active elasticity of the left ventricle. The following formula can calculate the left ventricular pressure at different volumes:

V₀ is the tension-free end-diastolic volume of the left ventricle and V _d is the tension-free end-systolic volume of the left ventricle.

Statistical methods

We use the CHISS2004 version of statistical software for data analysis, and the measurement data conforming to the normal distribution are expressed as mean ± standard deviation.⁶6. Zadvorev SF, Krysiuk OB, Obrezan AG, Yakovlev AA. Effect of personal history of athletic activity on the clinical course of cardiovascular diseases in former athletes. Advances in Gerontology. 2019;9(1):91-7. Paired t-test was used. Non-normally distributed, the median represents measurement data. Wilcoxon signed-rank test with the paired design was used. The count data is expressed as a percentage, and the χ2 test is used. P<0.05 indicates that the difference is statistically significant.

RESULTS

Blood BNP and cTnI levels of young men before and after long-distance running

The blood BNP level of each youth before and after the long-distance running was lower than 263μg/L, and the blood cTnI level was lower than 0.4μg/L ( Table 1 ).

Comparison of ECG results of young men before and after long-distance running

The heart rate increased significantly after long-distance running (P<0.01) ( Table 2 ). There was no atrial or ventricular arrhythmia and heart block in the ECG before and after the long-distance running, and no left ventricular high voltage and high T wave.

Medical observation

Sixty-three youths had no chest tightness, chest pain, palpitations, dizziness, headache, fainting, and fatigue during exercise and 1 day after exercise.

DISCUSSION

BNP mainly comes from the ventricle. Because the nucleic acid sequence of BNP contains the unstable TATTTAT sequence and its messenger RNA switches faster. This allows BNP to be synthesized instantaneously. BNP in the blood can reflect the ventricular volume and pressure load proportionally. And it can sensitively and specifically reflect the degree of ventricular dysfunction.⁷7. D’Ascenzi F, Caselli S, Alvino F, Digiacinto B, Lemme E, Piepoli M et al. Cardiovascular risk profile in Olympic athletes: an unexpected and underestimated risk scenario. British journal of sports medicine. 2019;53(1):37-42. In this study, the median blood BNP level was 15.90μg/L before long-distance running and 20.30μg/L after. This shows that the 5km long-distance running did not cause abnormal blood BNP levels in 63 young people. Cardiac troponin (cTnI and cTnT) is a protein present in atrial and ventricular myocytes. It is only expressed in the myocardium and has a high degree of tissue specificity. In this study, the median cTnI level was 0.010μg/L before long-distance running and 0.020μg/L after long-distance running.

ECG is an objective indicator that reflects the production, conduction, and recovery process of heart excitement, and its detection results can effectively reflect the basic functions of the heart. Sinus bradycardia is common in healthy young people. Sinus bradycardia is often accompanied by sinus arrhythmia.⁸8. Tso J, Kim JH. Master endurance athletes and cardiovascular controversies. Current sports medicine reports. 2020;19(3):113-8. Healthy people may have sinus tachycardia during physical activity. In this study, the proportion of young men with sinus bradycardia after 5km of long-distance running was lower than before (P<0.01). The reason is the adaptable physiological changes of the heart to long-term training. Sinus bradycardia is caused by increased vagus nerve tension. The heart rate increased significantly after long-distance running, and the proportion of sinus tachycardia was higher (P<0.01). The reason is that exercise leads to increased heart rate and sinus tachycardia caused by the excitement of the sympathetic nervous system, which is a normal physiological change of the human body.

Although there is no precise definition of myocardial injury caused by high-intensity exercise, many sports medicine studies have confirmed the myocardial injury caused by strenuous exercise. Inappropriate exercise can adversely affect the cardiovascular system. Mainly include arrhythmia, myocardial damage, changes in the shape and structure of the heart, heart failure, coronary artery disease, and even death.⁹9. Sanghera AS, Singh N, Popkave A. Running Marathons with Blocked Coronary Arteries and Runners’ Risk of Sudden Cardiac Death—Case Report and Review. Current sports medicine reports. 2020;19(3):107-9. The occurrence of cardiac events, including sudden death, has caused irreparable losses and serious adverse effects on the country, collectives, families, and individuals.

At present, there is still a lack of unified understanding of the early diagnosis criteria for sports-related cardiovascular injuries. Based on the monitoring of cardiovascular function, there are two traditional methods for timely detection of sports-related cardiovascular injuries: 1) Subjective assessment of fatigue from work. Among them, chest tightness, shortness of breath, palpitations, headaches, nausea, and other uncomfortable symptoms may also be normal reactions during exercise. 2) Objective evaluation methods include blood pressure, heart rate, blood oxygen, ECG, and cardiac ultrasound monitoring.¹⁰10. Laukkanen JA, Kunutsor SK, Ozemek C, Mäkikallio T, Lee DC, Wisloff U et al. Cross-country skiing and running’s association with cardiovascular events and all-cause mortality: A review of the evidence. Progress in cardiovascular diseases. 2019;62(6):505-14. The changes in cardiac structure and function caused by training include changes in heart rate, high left ventricular voltage, abnormalities in cardiac repolarization, ischemic changes, abnormalities in the origin of agitation, and myocardial wall thickening. Whether physiological changes or pathological changes are difficult to define, these methods have failed to achieve satisfactory results in timely detection of exercise-related cardiovascular injuries and the prevention of cardiac events. New myocardial injury markers represented by blood BNP and cTnI have the advantage of early assessment of changes in cardiac function and myocardial micro-injury. This has become an important indicator of exercise-related cardiovascular injury.

How much long-distance running may cause, damage to the heart has been the focus of sports medicine in recent years. Some scholars compared the blood BNP levels of 60 healthy soldiers before and after 10km long-distance running and found that the blood BNP levels increased significantly immediately after training. Some scholars have found that 70% of young athletes’ cTnT after 21km runs is higher than acute myocardial infarction’s diagnostic value. Some scholars reported that 40% of 60 adult athletes had blood cTnT levels exceeding the critical diagnostic value of myocardial infarction after a marathon. Some scholars tested the blood BNP and blood cTnT levels of 10 athletes before and after completing the 50km ultra-long marathon and found that the blood BNP and blood cTnT levels increased significantly after the exercise. And the difference of BNP before and after exercise is positively correlated with the difference of cTnT. These studies show that running more than 10km may lead to increased blood BNP and cTnT levels.

In addition, lack of adaptive exercise is an important factor in sports-related cardiovascular injury. Some scholars have reported that the recruits may have ECG abnormalities in the first 5km trail running. The content includes arrhythmia and ST-T changes. The blood cTnI of some recruits increased immediately after a 5km physical training and 4h after exercise. In comparison, the test soldiers did not experience obvious heart damage after 1 week of adaptation and then 5km physical training. The reason is the lack of adaptive exercises among the newly enlisted soldiers and the incoordination of the body’s sympathetic and vagus nerves. This leads to dangerous electrical activity of myocardial cells and increases myocardial vulnerability.

CONCLUSION

The 5km long-distance running did not cause abnormal changes in the three objective indicators of blood BNP, cTnI and ECG, and did not cause discomfort in the cardiovascular system. The reason is that the young and middle-aged in this study did not have newly enlisted soldiers, and they had all undergone adaptive training. The young man’s mental reserve can meet the exercise load of a 5km long-distance running.

ACKNOWLEDGMENTS

The study is supported by Tianjin Discipline Leading Talents Program Project(TJ-TYX-201901).

REFERENCES

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