Your heart is an engine, and it is capable of fascinating structural changes. Here are 10 things you should know about your heart, how exercise changes it and what it can't (because of genetics).
PLEASE NOTE: If you have any questions or concerns, please reach out to your medical advisor.
1. Exercise has overwhelmingly positive effects on your heart
Although strenuous exercise can pose an element of heart risk for an incredibly small minority, it’s important to keep this in perspective.
Very reliable data compiled over many years has shown that regular exercise is emphatically one of the best things we can do for our health because it:
- increases lifespan by reducing the risk of cardiovascular disease
- improves mental health
- reduces the risk of some cancers and other chronic diseases.
However, there are structural changes caused to the heart by high volumes of exercise, some of which can unmask underlying conditions or concerns you may not have known were there. There are also genetic predispositions that exercise can't control. Let’s dive into these here.
2. Athlete's Heart... what is it?
Athlete's Heart is the term used to describe the changes high volume exercise can make to the heart. The heart pumps oxygen-rich blood to the muscles and heart rate naturally increases in order to move more blood during exercise. Maximum heart rate is largely determined by age and biology and can’t really be trained, so the heart mainly adapts by pumping more blood per beat, or volume. With regular, vigorous aerobic activity, the athlete’s heart begins to remodel and change over time, growing larger and stronger, with increased blood flow capacity. The heart:
- becomes better equipped to transport oxygen
- better supports the higher metabolic demands of the exercising muscles.
- increases VO₂ max - a true measure of cardiopulmonary capacity
- tends to decrease resting Heart Rate significantly
Most people who exercise moderately never reach this degree of remodelling; it is primarily seen in competitive or high‑volume endurance athletes (usually more than 5 hours/week of vigorous training). The increased heart dimensions remain within accepted “upper limits” and usually mostly regress when intense training stops.
3. How much is too much?
There can be potential long‑term risks with extreme lifelong volumes of exercise. Some studies suggest that very high lifetime volumes (often >8–10 hours/week of vigorous endurance work over many years) may be associated with specific arrhythmias. For example:
- Some studies suggest that, in a minority of long‑term high‑volume endurance athletes, certain structural changes (such as dilation of the left ventricle or the atria) may be associated with arrhythmias, but overall, the benefits of regular exercise still clearly outweigh these risks.
- Athletes are 2-3x more likely to have atrial fibrillation (AFib) than the general population.
It should be noted that because of their overall fitness and their generally better health and resiliency, athletes with AFib have mostly been found to deal with the effects and repercussions better than the general population.
4. What exercise can't change.... your genetics
Exercise is undoubtedly good for your health. However, there are some genetically driven heart-health markers that athletes need to be aware of. Here are two of them:
5. Cholesterol
Athletes are not immune to high cholesterol. If you have a strong genetic tendency to high cholesterol, exercise alone is usually not enough to normalize it, but it still improves your lipid profile and overall risk. This should be monitored by a trained medical professional to prevent coronary artery disease and heart attacks.
6. High blood pressure
Blood pressure is influenced by both genetics and lifestyle. Regular exercise typically lowers blood pressure and is part of standard treatment, but many people still need medication as well. It should again be monitored by a trained medical professional and treated or medicated where appropriate.
To Note: Blood pressure medication containing diuretics can decrease electrolytes and sodium in the blood. You should discuss a fluid and electrolyte strategy with your doctor.
7. Does gender make a difference?
Historically, data was dominated by studies on male athletes, but newer studies show that female endurance athletes also demonstrate chamber enlargement and increased AFib risk compared with non‑athletic women, though absolute cardiac event numbers remain low. Most guidelines support the same exercise recommendations for women and men, with attention to sex‑specific issues (e.g., pregnancy, RED‑S).
8. Does age make a difference?
As athletes age, they’re naturally more prone to developing cardiovascular disease, regardless of how strong their heart may be. Fitness and an active lifestyle can help to protect against this, but not entirely.
Again, vigilance is the key. Besides seeing a specialist or your GP for regular screenings and bloodwork, it’s important that an older athlete seeks medical assistance immediately if they experience any warning signs.
9. The warning signs to look for
- An abrupt performance decrease e.g. the runner who can’t keep up as usual with other team members, or training times are suddenly impossible to reach.
- Feeling greater tiredness than usual
- Abnormal shortness of breath during or following a workout
- A burning sensation in the chest or upper abdomen, especially in athletes with no history of gastrointestinal problems or heartburn
- Abnormal tightness, numbness or locking in the shoulder, upper back or jaw.
It may just turn out to be indigestion, joint pain, dehydration, or a bit of over-training. But consulting a medical professional is much safer than avoidance or denial.
10. Exercise is GOOD
For the majority of people doing moderate to high exercise, the cardiovascular benefits (lower blood pressure, better vascular function, lower mortality) clearly outweigh these very unlikely potential risks.
The small, higher risk patterns tend to appear in athletes with decades of very high volume (e.g. multiple marathons or Ironman‑level training per year, intense training nearly every day, often over 10 hours per week), especially if there is underlying genetic susceptibility.
Expert groups generally recommend:
- Semi regular cardiovascular assessment for high‑volume masters athletes (history, ECG, and further imaging if required)
- Seeking a quick evaluation of warning signs such as unexplained fainting, palpitations, declining performance, chest pain, or disproportionate breathlessness.
- Building in rest, avoiding chronic overtraining, and managing traditional risk factors (blood pressure, cholesterol, smoking, sleep, alcohol).
One simple way to think about it:
Moderate and even fairly vigorous endurance training is strongly cardioprotective.
Pushing into the extreme, lifelong end of the spectrum may slightly increase the chance of AFib and certain structural changes while still leaving overall cardiovascular risk lower than in sedentary peers.
*Please note we are not medical professionals, and this is an informative piece using scientific literature, not medical advice. If you have questions or concerns, please reach out to your medical provider. When it comes to your heart, it is always better to be well informed and knowledgeable - only you know your own body enough to notice early warning signs.