Is Your Heart Ready for a Marathon?
Why is your heart at risk when you do extreme sports?
More and more people are catching the running bug and signing up for marathons. Some of them even go abroad to attend races each year. While the running bug isn't a disease in the conventional sense, it can, in rare cases, have harmful effects. Every now and again, we hear reports of runners both young and old suffering from sudden death while running. Most of these untimely deaths can be attributed to cardiac episodes. The incidence is rare – one in 100,000 – but the consequences are serious.
To help you understand why people can have cardiac episodes while exercising, let me explain what happens in your body when you do a physically demanding workout.
1. Adrenaline is released
When we engage in extreme sports, our bodies release large amounts of adrenalin in a very short time. Adrenaline is a hormone that speeds up your heart rate, increases oxygen consumption, elevates blood pressure, and increases heart workload. All of these require a strong heart to keep up.
2. You can become dehydrated
Intensive sports make our bodies lose a large amount of fluid, which can cause issues like dehydration, electrolyte imbalance, osmotic pressure variation, and fluid redistribution inside and outside the blood vessels. When you become dehydrated, your blood becomes thicker and more concentrated. This affects your blood flow and can cause blockages, which can be very dangerous. This adjustment process may induce acute cardiovascular events or even sudden death for those who have an underlying cardiovascular disease.
3. Your heart structure can change
Studies have shown that extreme endurance training causes temporary changes to your heart's structure, such as stretching of cardiac tissue or elevation of myocardium damage marker. Recurrent myocardium damage may cause permanent scarring to the left ventricle. This scar tissue makes the heart prone to cardiac arrhythmia, which is a common cause of sudden cardiac death, second to coronary disease.
4. Your blood vessels can become blocked
Another mechanism of cardiovascular damage as the result of extreme training is lipid particle buildup in the arterial walls. This can lead to artery lumen stenosis, which is the root cause of coronary artery disease.
Although cardiac assessment testing can't predict 100% of cardiac events that patients may experience during rigorous exercise, it can give us some clues about potential cardiovascular risks. For that reason, we recommend that some people get their heart health tested before embarking on a rigorous training program.
Who should get a cardiac assessment test before participating in a marathon?
The complications listed above can arise in runners both young and old, especially if they have a weak heart to begin with. That's why it's a good idea to get your heart checked before you start training to make sure it is up to the challenge of a marathon. See your doctor if you:
1. Smoke or drink heavily;
2. Have hypertension, diabetes, hyperlipidemia, or family history of premature coronary artery disease;
3. Have a sedentary lifestyle, obesity, insomnia, or lots of stress in your life;
4. Have a family history of sudden cardiac death;
5. Have a personal or family history of cardiac arrhythmia, including long QT syndrome, WPW syndrome, Brugada syndrome, extreme bradycardia or tachycardia, or heart conduction block;
6. Have experienced syncope (fainting) with an unclear cause;
7. Have significant changes in your blood levels of potassium or magnesium (e.g. if you are taking diuretic medications or suffer from serious diarrhea);
8. Have a history of drug abuse;
9. Take proarrhythmic medicine (which may increase the risk of fatal arrhythmia);
10. Have ever experienced exertional pain in your chest (or any area below the jaw and above the belly button) or shortness of breath and palpitations.
Which patients are advised not to participate in a marathon?
Some people will get their heart tested and be sent on their way with the all-clear from the doctor to go ahead and run. Other people may realize that they may put their heart at risk if willing to meet a goal as ambitious as finishing a marathon. This includes people who:
1. Have a history of large area myocardial infarction (75% of cardiac deaths occur in people with a history of heart attack, particularly in the first six months after having an acute myocardial infarction);
2. Are established coronary artery disease patients (including those diagnosed with angina, those who have had coronary stents placed, or those who have undergone bypass surgery);
3. Have experienced syncope (fainting) with an unclear cause;
4. Have congenital heart disease, cardiomyopathy, severe valvular heart disease, or vascular malformations.
What can healthy people do to protect their heart health while training for a marathon?
Here are several pieces of advice from the perspective of a cardiologist:
1. Train properly
Regular training prior to running a marathon is necessary to increase your cardiac reserve capacity and aerobic exercise capability. Don't just head to the starting line without sufficient training!
2. Take it easy
Keep regular and adequate sleeping hours and make sure you're well-rested. Long-term sleep deprivation increases the heart's workload, causing cardiac arrhythmia or elevated blood pressure problems.
3. Drink up
Water is absolutely vital for your blood circulation. If you don't drink enough, your blood will get thicker and won't pump around your body well. This can trigger a cardiac event. To avoid this, make sure you're drinking enough water when you sweat.
4. Know your limits
Make sure you stop and rest at the first sign of chest pain. That includes palpitations, shortness of breath, pain or pressure in the chest, or dizziness during running.
5. See your doctor
If the above cardiovascular risk factors exist or chest discomfort ever presents, please contact your doctor to undergo cardiac tests or a full cardiac assessment.
Dr. Shuling Bai is a Cardiologist and the Assistant Chair of the Cardiovascular Center at Beijing United Family Hospital (BJU). She has been a cardiologist for more than two decades. She brings to the BJU community her interests in common cardiac diseases, such as coronary artery disease, hypertension, arrhythmia, chronic heart failure, and acute cardiac diseases. Her specialty lies in the diagnosis and treatment of coronary artery disease. If you'd like to make an appointment with her, or if you'd like to do a cardiac assessment test at BJU, call our Service Center at 4008-919191.
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Are you a beginner runner? Read BJU Physiologist Ying Swee Ong's tips for preparing for a marathon without injuring yourself.
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