I've repeatedly cited gigantic peer-reviewed studies including the American Journal of Clinical Nutrition (1999) one in which participants were split into many groups based upon differing levels of activity from sedentary to daily runners. Each one has shown dose-dependent gains from cardio-vascular exercise. And in each case, you've shrugged off the research and then come back with something like this.

From your links: "Heidbüchel's study included only a small, highly selective population of endurance athletes, predominantly cyclists, who engage in a particular type of strain, with preexisting arrhythmias."

So even when you specifically searched for "runners die young", it came back with a paper that states that marathon running is part of a healthy lifestyle and then goes on to talk about possible risks for those who race without sufficient training or who are trying to undo decades of unhealthy living. Over half of the participants were former smokers. The paper does not in any way claim that "endurance sports can mess up your heart rhythm" nor is the quotation you took out of context representative. In fact, it said:

"Marathon running is part of a healthy lifestyle. There is overwhelming evidence for the cardiovascular protective effects of physical activity."

What is it with this? What ax to grind is so important that it's worth posting misleading, disingenuous summaries of research you find by googling for your already chosen conclusion? As I asked last time, Can you refer me to any peer-reviewed research linking sprint training or weight training with equal or greater benefit in any of the health indicators that Paul Williams's 100,000 person study found distance running improved?