During the last weeks the heart of athletes moved into the center of concern. There have been cases of sudden cardiac death, there have been athletes withdrawing from the sport because of heart issues. I thought it may be of interest for you as an endurance athlete to get an idea about what is still a normal heart and when is a heart under suspicion to be a sick heart.
Sudden cardiac death needs to be questioned. If one had known the history, the decent symptoms before the incident, if one had interpreted the signs correctly at the right time, maybe distress could have been prevented. An ECG can give a lot of information, if one is able to read it right. Looking at an ECG without knowing that it is an athlete’s heart, may lead to misinterpretation and panic. A physician needs the experience to read the curve. There are common and training-related abnormalities (up to 80%) of an athlete’s ECG. These physiological ECG abnormalities are more prevalent in highly trained endurance athletes than in other athletic subgroups.
Normal ECG curve
An endurance athlete’s heart undergoes structural changes that show in an ECG, not only the heart muscle thickens, also the conduction system of the heart works with a different rhythm. Regular physical work-out leads to an increased vagal tone which means that the heart beats slower (bradycardia) – of course, you know and feel that. Slight arrhythmic heart beats are not uncommon either. Especially, if the heart beats very slowly. These phenomena are functional which means they normalize during exercise, they don’t lead to dizziness or passing out and they are reversible, e.g. if training is discontinued. Cases of less than 30 beats/min and marked sinus arrhythmia needs closer attention, it may be a pathological condition like a sick sinus syndrome (those guys receive a pacemaker). Continue Reading →