The Chevron Houston Marathon takes place Sunday morning, and this Dale Robertson/Chronicle article tells the story of Dolph Tillotson, the Galveston Daily News publisher who almost died of a heart attack while training at Memorial Park in preparation for the 2004 marathon. Tillotson has now recovered to the extent that he is going to try and complete the marathon on Sunday, which is certainly a remarkable comeback.
But is Tillotson’s long-distance running making him healthier? Art DeVany argues that it does not and, in this recent post, notes a study from the Annals of New York Academy of Sciences that indicates that long-distance running is more dangerous to one’s health than conventional wisdom suggests:

Ann N Y Acad Sci. 1977;301:593-619.
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Coronary heart disease in marathon runners.
Noakes T, Opie L, Beck W, McKechnie J, Benchimol A, Desser K.
Six highly trained marathon runners developed myocardial infarction. One of the two cases of clinically diagnosed myocardial infarction was fatal, and there were four cases of angiographically-proven infarction. Two athletes had significant arterial disease of two major coronary arteries, a third had stenosis of the anterior descending and the fourth of the right coronary artery. All these athletes had warning symptoms. Three of them completed marathon races despite symptoms, one athlete running more than 20 miles after the onset of exertional discomfort to complete the 56 mile Comrades Marathon. In spite of developing chest pain, another athlete who died had continued training for three weeks, including a 40 mile run. Two other athletes also continued to train with chest pain. We conclude that the marathon runners studied were not immune to coronary heart disease, nor to coronary atherosclerosis and that high levels of physical fitness did not guarantee the absence of significant cardiovascular disease. In addition, the relationship of exercise and myocardial infarction was complex because two athletes developed myocardial infarction during marathon running in the absence of complete coronary artery occlusion. We stress that marathon runners, like other sportsmen, should be warned of the serious significance of the development of exertional symptoms. Our conclusions do not reflect on the possible value of exercise in the prevention of coronary heart disease. Rather we refute exaggerated claims that marathon running provides complete immunity from coronary heart disease.

DeVany — who has been studying physiology and exercise protocols for years — has accumulated a series of posts regarding the unhealthy nature and outright dangers of endurance training. The reality is that many endurance runners are not particularly healthy people, suffering from lack of muscle mass, overuse injuries, dangerous inflammation and dubious nutrition.
Tillotson obviously has great desire and discipline to be able to return to marathon running after almost dying of a heart attack. But his judgment in doing so is open to serious question.