The evidence for increased risk in endurance athletes
Usually a person with atrial fibrillation feels fatigued and may be aware of palpitations – an irregular heart beat. Instead of a well organized contraction of the atria followed by a regular contraction of the ventricles, the walls of the atria contract in a poorly coordinated manner and blood is not transferred to the ventricles in a way that ensures efficient filling of the ventricles before ventricular contraction ejects the blood into the pulmonary artery (that connects the right ventricle to the lungs) and the aorta (that carries blood from the left ventricle to the rest of the body). That is atrial fibrillation.Ītrial fibrillation is a disturbance of heart rhythm in which the electrical events that initiate contraction do not arise in a regular manner from the sinoatrial node embedded in the muscle of the right atrium of the heart, but instead arises in a chaotic manner from a variety of different sites in the walls of the atria. However there is one heart problem that is relatively common and might arise largely from factors related to fitness itself. The risk of heart attack following a marathon is small but real, though it is generally accepted that this risk often arises from underlying heart abnormality. There is little doubt that the balance of benefits and risks to the well-being of the heart arising from regular running favours the benefits.