The conventional wisdom that marathons are a dangerous cause of fatal heart attacks is a myth, says a study, which found that the staging of these races in fact reduces deaths -- from road accidents.
The media like to headline the sudden deaths that occur among marathon runners, but the truth is that by blocking off roads to stage events, organisers save lives from traffic mishaps, it says.
Researchers led by Donald Redelmeier of the University of Toronto in Canada randomly selected 26 established marathons involving three million participants over a 30-year period.
Each of the marathons had at least 1,000 runners and took place on US roads.
The investigators recorded the tally of fatal heart attacks that occurred in the marathons, as well as the number of fatal accidents that happened on the same roads during the same hours, one week before and one week after each marathon.
They also tallied deaths that occurred in state counties outside the marathon route, to see if these had been affected by a spillover in traffic caused by closed-off roads.
Over the three decades, there were 26 fatal heart attacks that occurred in the marathons -- but because of road closures, 46 fatal traffic accidents were prevented, amounting to a relative risk reduction of 35 percent.
Redelmeier's team also found evidence to back the wisdom that the last mile (1.6 kilometres) of a marathon is the hardest and say paramedics and ambulances should give special priority to deploying at the end of the race.
During this stretch alone, nearly half of the sudden cardiac fatalities occur, they say, speculating that the final sprint -- followed by a sudden cessation of movement -- may be more dangerous than usually realised.
The paper is released on Friday by the weekly British Medical Journal (BMJ).