Regarding The Daily Progress story about the tragic loss from a heart attack of a 68- year-old male soon after a 10K race ("Herr, UVa researcher known for product innovation, dies," Sept. 22):The death should not be surprising. It could stem from high adrenaline levels, particularly near the finish line.Those competing in a 10K race or a marathon, particularly with aging, are well advised to avoid accelerating their speed as they approach the ending.The mechanisms conducive to a heart attack stem from high- adrenaline-related injuries to the coronaries with, in turn, heart muscle loss. In addition, particularly in hot weather, low magnesium levels, intensified by sweating, can be a factor. With the incidence of Mg deficiencies being at least 60 percent in the United States, and a worldwide problem, runners should be aware of this universal risk.With running, particularly in the heat, there is a greater risk of a heart attack or sudden death because of the combination of high adrenaline, low Mg and vicious cycles between the two. In order to reduce very high adrenaline levels, the runner must be well hydrated before the race and on a high-magnesium diet with well-absorbed magnesium supplements but avoiding calcium supplements, water softeners and cola drinks, which all lower magnesium levels.