Attention Marathon Runners: you need to train more than 40 miles/week before a marathon

Re: Stress to the heart muscle
Average marathon runners, those who run less than 40 miles per week during training, risk cardiac problems (temporary heart muscle weakness and increased pressure in lung arteries) after a race. Those who ran more than 45 miles a week had no signs of damage after completing the marathon. (Boston Marathon runners took part in this study.)