In fact, not only are organised marathons not associated with an increased risk of sudden death, but they reduced the numbers of fatalities in car accidents because of associated road closures.
Donald Redelmeier and Ari Greenwald, in a study published in the British Medical Journal, looked at risk of sudden death when competing in a marathon compared with the risk of dying from a motor vehicle crash that might have taken place if the roads had not been closed.
They analysed marathons with at least 1000 runners that had been taking place for at least 20 years on public roads in the USA between 1974 and 2004. This provided results for more than 3 million runners on 750 separate days, equivalent to about 14 million hours of exercise. During all these hours of exercise there were 26 sudden cardiac deaths observed - a rate of 0,8 per 100 000 runners. They also found that, because of road closures, an estimated 46 deaths in motor vehicle accidents were prevented, equivalent to a relative risk reduction of 35%. This is effectively nearly 2 crash deaths saved for every sudden cardiac death.
This net reduction in total deaths couldn't be explained by re-routing traffic to other roads or days and was consistent across different parts of the country, decades of the century, seasons, days of the week, difficulty of the course and the degree of competition.
Sudden death during a sporting event such as a marathon or a long-distance cycling event, such as The Cape Argus Cycle Tour, generates a huge amount of media attention. This has led to a misconception among certain sectors of the population that these kinds of sporting events are harmful to health. While we do know that running a marathon can lead to sudden death, which, as the authors point out, was well documented 2500 years ago, running marathons actually cuts the net death rate, both by preventing car crashes and reducing individual risks of cardiac disease.
For the full text of this article, see here http://www.bmj.com/cgi/content/full/335/7633/1275
