The media has gotten a hold of a case report from the University of Maryland describing a 51-year old physician who, despite being a long distance runner, had a high heart scan score.
An example of the report can be found at
Heart Disease In A Marathon Runner: Is Too Much Exercise A Bad Thing?
http://www.sciencedaily.com/releases/2007/03/070315091100.htm in Science Daily.
"The mystery was all the more intriguing because his resting blood pressure and fasting cholesterol levels, the usual measures of cardiovascular health, were in the normal range."
When this man was put on a treadmill for a stress test, his blood pressure skyrocketed from a normal 118/78 to 230/78--extremely high, even for exercise. The physicians reporting the case raised the question of whether long-distance running represents a risk for heart disease and if the high blood pressure with exercise is a contributor or cause of the high heart scan score.
These are phenomena we are very familiar with. We have stressed the importance of exercise blood pressure as a trigger for coronary plaque for years. While 230/78 is clearly too high, we find that any blood pressure over 170/80 with exercise adds to the fire and can trigger plaque growth.
However, I think it is absurd to suggest that marathon running itself is a trigger of coronary plaque. I think it is far more likely that the person described in the report had lipoprotein(a), a potent trigger for both exercise-induced hypertension and high CT heart scan scores in seemingly well people. He likely also suffered from a deficiency of vitamin D deficiency, another contributor. There's no need to indict exercise.
If you are in the Track Your Plaque program, you know that stress tests are of questionable helpfulness for the detection of hidden heart disease. But they are useful for assessment of blood pressure responses during exercise. If BP exceeds 170/80 at 10 mets (a measure of exercise effort achieved by walking 3.4 mph at a 14% grade for 3 minutes), then blood pressure may be a contributor to your heart scan score.