Updated: Jun 15, 2019
The term 'athletic heart' is given to 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 athletes. These changes in part vary with sporting discipline, gender, age and ethnicity. These 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 doctors who have experience in sports cardiology.
The left ventricle (LV) delivers oxygenated blood to the body. It is the largest and most muscular of the 4 cardiac chambers. This assessment of LV cavity size has been shown to be increased in some athletes when compared to healthy controls. Whilst athletes demonstrate increased cavity dimensions it is unusual for LV cavities to reach the proportions of dilatation that we would expect with a pathological condition. Most male and female athletes will have LV chamber dimeter within normal limits although LV size which exceeds normal limits can be seen in athletes (usually those in high capacity endurance sports (e.g. endurance cycling or running).
Sheikh et al compared LV cavity size between black and white adolescent athletes (aged 14 – 18 years). This current study did not show any significant difference between athletes from different ethnicities for LV cavity dimension.
One way to estimate the overall heart pump function is to calculate the 'ejection fraction'. A normal ejection fraction varies slightly with gender. Studies have shown that certain athletes can have ejection fraction values that would fall into those seen with pathological LV dysfunction (ejection fraction 45%-49%). This is seen in a minority of athletes particularly high-end endurance participants. Abergel et al study Tour De France cyclists and showed that in a group of 286 elite cyclists, 147 (51.4%) demonstrated LV end diastolic dilatation (>60mm) and of these 17 (11.6%) demonstrated reduced ejection fraction (<52%).
We can now see that certain athletes may fall into a 'grey' zone where there is LV dilatation and a mildly reduced ejection fraction. This can mimic a pathological heart muscle weakness. It is therefore important that these individuals are assessed by physicians with a specialty in sports cardiology to help differentiate physiology from pathology.