“Each of these news may surprise you but to us cardiologists, outward fitness alone is not a clean chit for heart health. That’s a dangerous simplification. There are a mix of risk factors and undiagnosed underlying conditions that stress the heart. Genetics plays a big role among Indians. Then there are inflammation, insulin resistance, stress, poor recovery, strenuous activity, sleep deprivation, silent hypertension and hidden arterial plaque, all of which operate beneath the surface, frequently without symptoms. By the time the body signals distress, the damage may have been done,” says Dr Ranjan Shetty, lead cardiologist and medical director, Sparsh Hospital, Bengaluru. “Sometimes visceral fat, abnormal lipid profiles or inherited vulnerabilities can remain undetected for years,” he told The Indian Express. Excerpts:

The hidden danger inside the athlete’s body

Sometimes there are structural changes in the heart among athletes who do strenuous exercise for over an hour on most days of the week. Most of the time, these changes aren’t excessive. However, in some athletes, the heart muscle thickens and the left ventricle widens.

These changes do not always cause heart attacks but can be a risk factor with undiagnosed, underlying genetic conditions. Sometimes a viral infection may cause inflammation in the heart. Strenuous physical activity while the heart is inflamed can trigger rapid, abnormal heart rhythms and sudden cardiac arrest, when the electric impulses of the heart shut down. For athletes over 35, there could be mild underlying blockages or plaques. During the massive cardiovascular stress of a game, blood pressure spikes and a piece of the small plaque can rupture. A broken plaque causing only partial blockage may remain unnoticed until this moment of extreme exertion causes rupture. Once that rupture occurs, the body responds by forming a clot, which can abruptly cut off blood supply to the heart muscle, resulting in a heart attack.

Doctors point out that such individuals never display obvious warning signs. Some may occasionally experience palpitations, dizziness or unexplained fatigue but dismiss them as stress or exhaustion. Others have no symptoms at all.

Being an active-sedentary person

Some people exercise intensely for an hour while remaining sedentary for the rest of the day. A morning run or evening gym session cannot entirely offset 10 to 12 hours of chronic sitting, erratic eating and sustained psychological stress. The body experiences these contradictions cumulatively, not separately.

Poor hydration, inadequate recovery, sleep deficits and stimulant-heavy pre-workout supplements often compound the risk.

The risk of dehydration

Dehydration can significantly increase cardiac stress. When the body loses fluids, overall blood volume drops, causing the blood to become thicker and more viscous, which raises the likelihood of clot formation. To compensate for the reduced circulating volume, the heart is forced to pump harder and faster to maintain blood pressure and oxygen delivery, placing additional strain on the heart muscle.

At the same time, dehydration disrupts critical electrolytes such as sodium and potassium that regulate the heart’s electrical activity, potentially triggering palpitations or dangerous arrhythmias. Blood vessels may also constrict in an attempt to conserve fluid, leading to a rise in blood pressure. Combined with thicker blood and narrowed vessels, these changes can increase the risk of a coronary blockage during intense physical activity.

Why preventive care is a must

General fitness tests mostly assess physical conditioning and lung capacity, but they are not designed to detect hidden cardiac disorders. This is why sports cardiologists increasingly emphasise dedicated cardiovascular screening for athletes and highly active individuals.

There’s the 12-lead ECG, which records the heart’s electrical activity and helps identify abnormal rhythms, inherited electrical disorders and early warning signs of structural disease. An echocardiogram, or ultrasound scan of the heart, provides detailed images of the heart’s chambers, valves and pumping function. Of course there is calcium scoring, which measures plaque deposits in arteries. Some doctors recommend a cardiac MRI, which reveals detailed three-dimensional pictures of the heart muscle and can reveal subtle abnormalities, tissue scarring or early inflammation that may not appear on ultrasound.

Athletes may also undergo an exercise stress test, in which the heart’s electrical activity is monitored while the individual runs on a treadmill or cycles. Some cardiologists use ambulatory ECG monitoring through Holter or event monitors, portable devices worn continuously for 24 hours or longer. These help detect intermittent rhythm disturbances that may not occur during a short hospital examination. When it comes to the heart, preventive check-ups should be priority.