The endurance athlete’s heart function
The endurance athlete’s heart function is like a finely tuned engine adapted to the demands of regular and intense training. The heart, the body’s central pump, is responsible for circulating blood, and delivering oxygen and nutrients to tissues.
Heart Adaptations in Endurance Training
Endurance athletes develop their hearts through systematic training. Prolonged and consistent endurance activities such as skiing, running, cycling, triathlon, and swimming lead to heart enlargement, especially of the left ventricle, which pumps oxygen-rich blood to the body. This phenomenon is known as cardiac hypertrophy. With hypertrophy, the heart can pump a greater volume of blood with each contraction, enhancing oxygen transport and improving performance.
Endurance athletes often have lower resting heart rates than less active individuals. According to Maastohiihto.com, resting heart rates can be below 40 beats per minute in highly trained athletes, compared to the usual 60–80 beats per minute. A lower resting heart rate signifies an efficient heart capable of pumping more blood with each beat.
Some world-class endurance athletes, such as Lasse Viren, have been recorded with resting heart rates below 30 beats per minute.
Read more: How much energy does an endurance athlete need?

Johan Hoel (NOR), Andreas Nygaard (NOR), (l-r) – Ski Classics Birkebeinerrennet, Rena-Lillehammer (NOR). www.nordicfocus.com. ¬© Reichert/NordicFocus.
Circulatory System and Heart Function
An endurance athlete’s heart function is crucial for great performance. The circulatory system comprises the heart, blood vessels, and blood. The heart pumps blood through arteries to tissues, where oxygen and nutrients are delivered to cells, and carbon dioxide and waste products are collected. The blood then returns via veins to the heart and lungs, where it is reoxygenated.
The heart operates as a four-chambered pump: two atria and two ventricles. The atria receive blood from veins and pump it into the ventricles, which then pump it to the arteries. The heart’s right side handles oxygen-depleted blood, sending it to the lungs for oxygenation, while the left side manages oxygen-rich blood, pumping it throughout the body.
During exercise, heart rate and stroke volume increase, boosting cardiac output (the volume of blood pumped per minute). This enables more oxygen delivery to muscles requiring energy for physical activity. Endurance athletes’ hearts adapt better to these demands than non-athletes’ hearts.
While regular exercise promotes heart health, excessive or poorly executed training can be harmful. Overtraining, insufficient recovery, and overly intense workouts may lead to heart issues such as arrhythmias or myocardial damage. High blood pressure, high cholesterol, smoking, and unhealthy diets can also compromise cardiovascular health.
Heart Risks and Challenges for Endurance Athletes
Endurance athletes may face unique heart challenges, such as exercise-induced arrhythmias, cardiac hypertrophy, or myocarditis. These issues often arise from overtraining, inadequate recovery, or training while ill. Monitoring training, listening to one’s body, and avoiding exercise when unwell are crucial for preventing serious complications.
Decades of intense training can also have cumulative effects. Veteran athletes may experience electrical problems like atrial fibrillation or an increased risk of myocardial thickening and scar tissue. Regular monitoring and age-appropriate adjustments to training are vital for maintaining long-term heart health. Balanced training and adequate recovery are key to sustaining heart health over time.
Read more: Mental training makes a champion
Doping and Its Dangers to the Heart
Performance-enhancing drugs like erythropoietin (EPO) can significantly harm the heart and circulatory system. EPO increases red blood cell counts, enhancing oxygen transport and performance, but it also thickens the blood, raising the risk of circulatory issues such as blood clots, heart attacks, and strokes.
Other substances like anabolic steroids can cause myocardial thickening, high blood pressure, and arrhythmias. Long-term use may lead to severe heart damage and sudden death, especially when combined with substances like alcohol.
Endurance athletes who have used performance-enhancing drugs during their careers may face lifelong cardiovascular and circulatory health issues. Doping’s effects may necessitate ongoing medical treatment and compromise overall health long after retirement.
Conclusion
The endurance athlete’s heart is uniquely adapted to continuous physical exertion, often larger and more efficient than non-athletes’ hearts. While endurance sports enhance cardiovascular function, excessive training without proper recovery can lead to heart problems. Veteran athletes face specific heart health challenges due to prolonged training stresses. Performance-enhancing drugs can have devastating and lasting effects on cardiovascular health.
Finding a balance between training and rest and regularly monitoring heart health are essential for long-term success and well-being.
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