The term 'athletic heart' or ‘athletes heart’ is given to the structural and electrical changes that can occur to the heart in response to long term sports participation. Athletic training regimes often exceed ‘normal’ physical limits and if continued, cardiac adaptation to exercise can occur in sports participants. These changes in part vary with sporting discipline, gender, age and ethnicity. The cardiac changes seen in athletes (called ‘Athletes Heart’) can sometimes mimic mild forms of cardiac disease. It is therefore important that cardiac screens in athletes / sports participants are carried out by medical professionals who have knowledge and experience in sports cardiology.
The left ventricle (LV) delivers blood containing oxygen to the body. It is the largest and most muscular of the 4 cardiac chambers. Most male and female athletes will have LV chamber size within normal limits although LV size which exceeds normal limits can be seen in athletes and sports participants who undertake increased volumes of aerobic exercise and sports.
One way to estimate the overall heart pump function is to calculate the 'ejection fraction' (EF). A normal ejection fraction varies slightly with gender. EF is the calculated percentage of the amount of blood which leaves the heart with each heart beat (this is called the ‘stroke volume’) out of the maximal volume of the heart (this is called the ‘end diastolic volume’).
As a result of an increased volume of aerobic sports participation the heart size increases and this ejection fraction can be ‘low normal’ or slight reduced. This is a physiological response to exercise.
Certain athletes can have ejection fraction values that are mildly reduced and would fall into those seen with pathological LV dysfunction (usually EF 45-50%). Abergel et al studied Tour De France cyclists and showed that in a group of 286 elite cyclists, 147 (51.4%) had an enlarged left ventricle and of these 17 (11.6%) demonstrated reduced ejection fraction.
We can now see that certain sports participants may fall into a 'grey' zone where there is heart enlargement and also a mildly reduced ejection fraction. This can mimic pathological heart muscle conditions (‘dilated cardiomyopathy’). It is therefore important that these individuals are assessed by physicians with an understanding and experience in sports cardiology to help differentiate physiological adaptation to sports from a pathological process.
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