Way back in 2010, when I was still a very active endurance athlete, racing 10 or more times a year, I remember one particular visit to my doctor for a routine physical. That’s when I was told I had “athlete’s heart.” My doctor quickly followed up by saying it was nothing to worry about and was common among endurance athletes. I took that reassurance to heart (so to speak) and went on with my life. The term never came up again.
Fast forward to 2019. I was diagnosed with an aortic aneurysm, a much more serious and life-threatening condition. That news triggered a memory of the earlier diagnosis and my doctor telling me my heart was enlarged. Since I was now in a different hospital network, they didn’t have records from that earlier visit. And I didn’t recall many details, just that two different diagnoses now pointed to an enlarged heart. I couldn’t help but wonder:
- Were these two conditions related?
- Had the aneurysm existed back when I was first told I had Athlete’s Heart?
I may never know the answer to the second question, but the first is worth exploring. Let’s get into it.
What is Athlete’s Heart?
According to the Cleveland Clinic, Athlete’s Heart is a natural adaptation of the heart’s left ventricle in response to regular endurance training, typically one hour a day, most days of the week. This training causes the left ventricle to enlarge, allowing it to pump more efficiently during exercise.
- It’s a benign condition with no symptoms
- Most common in Black athletes
- Seen in roughly 2% of endurance athletes
- Usually develops after years of strenuous training
In short, it’s considered a normal and harmless physiological change. So, nothing to worry about, right? Not so fast.
Athlete’s Heart vs. Hypertrophic Cardiomyopathy
While Athlete’s Heart is a healthy adaptation to consistent training, it can sometimes resemble a much more serious condition: Hypertrophic Cardiomyopathy (HCM).
HCM is a pathological (i.e., abnormal or diseased state) condition that causes thickening of the heart muscle, particularly the walls of the left ventricle. Unlike Athlete’s Heart, HCM is:
- Genetic (runs in families)
- Found in about 1 in 500 people
- Sometimes appears during the teen years
- A known cause of sudden cardiac arrest in young athletes
Most people with HCM live normal lives, but because of its potential severity, it’s critical to rule out HCM when you’ve been told you have an enlarged heart.
How to Tell the Difference
A report from the NIH titled “Distinguishing Hypertrophic Cardiomyopathy from Athlete’s Heart” provides helpful insight. In cases where heart wall thickness falls in the “grey zone” (13–15 mm), the following criteria can help differentiate the two:
| Characteristic | Athlete’s Heart | HCM |
| Family History | No genetic link | Often hereditary |
| VO2 Max | > 45 ml/kg/min | Usually lower |
| Electrocardiogram (ECG) | Normal | Abnormal or “bizarre” |
| Left Ventricle Cavity Size | > 55 mm | < 45 mm |
If you’ve been told you have Athlete’s Heart, it’s worth reviewing these distinctions with your doctor. In some cases, additional testing such as echocardiography, cardiac MRI, or genetic screening may be recommended.
Final Thoughts
Athlete’s Heart is generally nothing to worry about. But given how closely it can resemble more serious conditions like HCM, it’s worth digging a little deeper. If you’ve been told your heart is enlarged, or you’ve pushed your body through years of endurance training, have a conversation with your doctor. It could bring peace of mind or possibly save your life.