Why do runners die during marathons?

When a death of a runner participating in a marathon makes its way to newspapers and media front pages people talk about how sad that is and question on how fit the person was or even if running 26.2 miles is healthy at all. When you have a more detailed read you may get some clues on the actual conditions under which the misfortune happened but usually not in-depth medical explanations. Joe English, coach and blogger, details some of the usual causes that may end up in a death in an endurance competition: heart disease, heart genetic defect or low blood sodium levels. His post is based on research and his own experience (so not from a strict direct medical source) and also points some heat and dehydration illnesses as potentially life-threatening conditions. Worth a read.