Tuesday 26 April 2011

Why cycling to work is one of the biggest causes of heart attacks

I bet that headline got your attention! I can't claim it though. It appeared over a story in the Daily Mail on 24th February claiming that commuting by bike is one of the main triggers of heart attacks.

Of course it's utter nonsense.

While it's based on a possible interpretation of a report summarizing a group of medical studies, the headline is typical of the modern phenomenon where papers misrepresent scientific results to grab attention. While this might appear to be a relatively trivial complaint, it isn't. This kind of deceit can do untold damage.

In this case the clue to the lie is in the words used in the headline versus those used in the story. The headline shouts out that cycling is the "CAUSE" of heart attacks. But if you read on you'll discover that the actual study concerned the "triggers"of heart attacks. In other words cycling in heavy traffic and polluted air, in a small number of cases, was found to be the possible final trigger that brought on a heart attack in some people who were on the verge of one anyway. It wasn't the cause.

But, having seen the headlines being generated around the world trumpeting the dangers of cycling, one of the reports authors, Prof Tim Nawrot was driven to say: "You can't conclude that from our analysis. The title was wrongly worded. I don't agree that cycling is not good for you. Physical activity is a very good way to prevent chronic diseases."

In fact the report concluded that exposure to traffic, including in a car, exposure to air pollution and physical exertion can trigger heart attacks. Put them together and what is the only possible conclusion? That's right, BIKING KILLS!!!!

Prof Nawrot went on to say that "Air pollution and traffic fumes can make existing heart conditions worse. But if your heart is healthy, there's far more to be gained from cycling or from any other form of outdoor aerobic exercise than sitting at home with the windows closed."

Far from causing heart attacks cycling is one of the best ways of preventing one.

As Ben Goldacre has repeatedly pointed out in his Bad Science column and blog (http://www.badscience.net/),  the tabloids, and the Daily Mail in particular, have never been ones to let the truth get in the way of a good science scare. The problem is that these stories do affect behaviour. Remember MMR!

Will the Daily Mail sponsor a study into how many people have heart attacks because they're scared to cycle to work in case they have a heart attack!

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