After a particularly gruelling workout or marathon, the body releases inflammatory chemicals and free radicals. (Source: Pexels)Sometimes a patient can confound us completely. His blood pressure was impeccable: 118/78 mmHg. His blood cholesterol levels were normal. Blood sugar in range. At 44, he was lean, disciplined and a regular at the gym. He ran long distances, never skipped a workout and prided himself on being fanatic about it and being fitter than most men his age. And then he had a heart attack.The question is as unsettling as it is common: How can someone who does everything right suffer a cardiac event? The answer lies in an uncomfortable truth. Medicine understands a great deal about heart disease, but not everything. While 90 per cent of heart attacks are traceable to identifiable risks, 10 per cent tend to be confusing and arise from other reasons entirely.The hidden culprits: Homocysteine and hs-CRPTwo markers that have drawn increasing attention are homocysteine and high-sensitivity C-reactive protein (hs-CRP). Homocysteine is an amino acid produced by the body. Elevated levels have been linked to damage to the inner lining of blood vessels, making arteries more vulnerable to plaque formation and clotting. An hs-CRP (High-Sensitivity C-Reactive Protein), meanwhile, is a marker of inflammation. Scientists now recognise that inflammation is not merely a consequence of heart disease; it is often a driving force behind it. Persistent inflammation can destabilise plaques in the coronary arteries, making them prone to rupture and trigger a heart attack.Neither test is recommended routinely for everyone, and neither offers definitive answers. But in patients who appear healthy and still develop cardiovascular disease, these markers may reveal risks hidden beneath normal cholesterol and blood pressure readings.Can too much exercise become harmful?Regular physical activity remains one of the most powerful ways to prevent heart disease. But an important distinction is often overlooked: regular exercise is not the same as relentless exercise.Over the past decade, researchers have begun to ask whether years of aggressive endurance training — marathon running, ultra-distance cycling, high-intensity workouts performed without adequate recovery — may, in some people, exact a price. The evidence is still evolving but several concerns have emerged.Every intense workout pushes the heart to pump harder and faster. In moderation, this stress is beneficial. The heart becomes stronger and more efficient. But when intense exercise is repeated over years without sufficient recovery time, especially after the age of 40, the heart muscle may undergo structural changes.Story continues below this adStudies have found that some veteran endurance athletes develop scarring or fibrosis — tiny patches of scar tissue within the heart muscle. Scarred tissue can disrupt the heart’s electrical system and increase the risk of rhythm disturbances.Extreme exercise is a controlled form of physical stress. After a particularly gruelling workout or marathon, the body releases inflammatory chemicals and free radicals. Usually, these changes are temporary and the body repairs itself. But when recovery is inadequate and extreme training becomes habitual, low-grade inflammation may persist.The paradox of coronary calciumPerhaps the most surprising finding has been the observation that some lifelong endurance athletes have higher coronary artery calcium scores than moderately active individuals. Coronary calcium is a marker of plaque buildup in the arteries that supply blood to the heart.Researchers are still debating what this means. Some argue that the plaques in athletes are more stable and therefore less dangerous. Others worry that years of repetitive physiological stress may accelerate arterial ageing in susceptible individuals. What is clear is that marathon medals do not confer immunity from coronary artery disease.Story continues below this adThe body changes with age. Arteries gradually lose elasticity. Recovery slows. Hormonal shifts affect muscle repair and cardiovascular resilience. A workout routine that felt effortless at 30 may impose a very different physiological burden at 45. That does not mean middle age is a time to retreat from exercise. Quite the opposite. But it does mean listening to the body becomes more important than conquering it.Chest discomfort, unexplained breathlessness, dizziness, unusual fatigue or palpitations should never be dismissed simply because one is fit. Fitness is not a guarantee against heart disease. Even here you need moderation.(Dr Shetty is lead cardiologist and medical director at Sparsh Hospital, Bengaluru)