As bike riders and racers, we train extensively, we eat right, we don't smoke and we're not obese. Heart-wise, this should put us way ahead of the curve. Recently, however, there are increasing reports of competitive athletes experiencing major cardiac events.
How can a heart that sustains a major aerobic effort be vulnerable to a heart attack?
Sudden, unexpected cardiac events in athletes are usually caused by "acquired" heart disease. That is, the same heart disease present in sedentary overweight truck drivers. Here we'll explore how these events occur, how one "acquires" the disease and ways you can safeguard against sudden cardiac failure.
The Science of an Attack
The heart is a large muscle that pumps 100,000 times daily. The muscle requires blood to contract. Blood is delivered to the beating heart muscle by the coronary arteries, which are on the surface of the heart.
"Acquired" heart disease involves the build up of cholesterol, fat and scar tissue inside these blood vessels. Less appreciated, but more important, are the reactivity of the coronaries and the stickiness of the blood passing through them. The sensitivity of the vessel and the stickiness of blood are both inherited and affected by lifestyle.
Inflammatory stimuli like adrenaline (racing), trans-fats, poor sleep and tobacco make the inner lining of the coronary vessel more reactive and thus more likely to fissure. These same stimuli activate blood platelets, making the blood stickier.
A fissure exposes the vessel to the sticky platelets. Platelets then attract more platelets and, similar to a cut on the skin, a clot forms. A clot inside the coronary stops the flow of nutrients to the muscle. A "heart attack" occurs and may cause electrical chaos leading to sudden death.
Blockages in blood vessels most likely to fissure are young, immature and not obstructive. For example, a common medical board question is, which lesion is more likely to cause a heart attack, an 80-percent blockage or a 20-percent blockage?
The answer is the 20-percent blockage, which is more "irritable." It is less stable and more likely to fissure, causing blood to clot on it. An 80-percent blockage is older, has a "smoother" cap and is less likely to expose the sticky parts of blood to an adhesive surface.
Unlike a chronic heart disease patient, whose heart is in a constant state of compromised blood flow ("pre-conditioning"), an athlete's heart is accustomed to perfect blood flow. Abrupt disruption of nutrients to a heart unaccustomed to compromise creates an electrically unstable situation. In the event of a complete coronary obstruction, this lack of "preconditioning" makes an athletic heart more susceptible to cardiac problems.
Isn't Exercise Healthy?
A common sentiment among the endurance sports community regarding cardiovascular health sounds something like this: "I am an athlete. I thought exercise made my heart healthier."
Generally, this is true, but here are four facts of an athletic lifestyle that may contribute to irritable blood vessels and stickier blood.
1. Statistically, bike racers are more likely to have the "minor" 20-percent blockage rather than the more obstructive, but less irritable 80-percent blockage. These non-symptomatic, undetectable blockages are repeatedly exposed to the spiking adrenaline levels of a typical athlete's life—a potentially risky scenario.
2. Bike racing is intense. A criterium, a 'cross race and even a century are different endeavors than most structured 30-minute aerobic workouts. Intense race-like efforts result in high adrenaline levels and marked cardiac stress. Much like an argument spikes adrenaline levels, so do intense physical efforts.
3. Bike racers are often "Type A", high-adrenaline, overachiever personality types.
4. Racers often over train and are poorly rested. Lack of rest can result in stickier blood and inflammation of the blood vessels.
Interestingly, in nearly three in 10 people, their first symptom of heart disease is sudden death. For the most part, bike riders and racers have "fitter" hearts than the general public. However, our lifestyle has specific stressors. Understanding and managing the life factors responsible for inflammation of blood vessels and the stickiness of blood will help reduce sudden cardiac events.
A Bike Racer's Checklist for a Healthy Heart
- Be informed and engaged in your heart health. Know that athletes are not immune to heart disease.
- Know your genetics. A strong family history of heart disease mandates extreme vigilance. Genetics are the strongest risk factor.
- Food is important. Nuts, fish, berries and vegetables are soothing to blood vessels. Man-made foods, especially "white" foods, are inflammatory.
- Keep your blood pressure less than 130/85.
- LDL ("Bad cholesterol") should be lower than 100 or preferably <70.
- Sleep well consistently. Quality sleep decreases inflammation and blood stickiness.
- Manage stress and anger. For competitive athletes, this is an especially pertinent issue.
- Do not ignore warning symptoms like chest pain, excessive shortness of breath or fainting.
- Seek out a doctor who exercises, competes or has experience with an athletic lifestyle.
John Mandrola, MD, is a cardiac electrophysiologist (heart rhythm specialist) who practices in Louisville, Kentucky. He is also a Cat. 2 Masters racer on the Papa John's Racing Team. He blogs about health, fitness and bike racing at drjohnm.blogspot.com.
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