Archive for October, 2012

School journeys and child fitness

15/10/2012

There were quite a few interesting replies to my tweets (@cyclingscience1) about recent papers that had been published in science journals and they have  prompted me to contact a scientist involved in the original research.

The paper that had got the most interest was about the fitness benefits for children who cycle to school. The original research was done by a team from the University of Granada, Spain and published in Preventive Medicine, August 2012.

In summary, it said that children who cycled to school in Sweden over a six year period were improved their fitness 20% more than those who walked. That’s understandable, particularly if they had hills on their routes.

The strangest fact, though, was that the cyclists were found to improve their fitness by only 13% more than children who went to school by “passive” modes (car, train, tram or bus) over six years.

So it would suggest that children who go to school in a car or other vehicle get 7% fitter than walkers.

Surely that can’t be right? Why should active walkers be less fit than the apparently inactive “passive” pupils?

A few ideas about this were mooted via tweets. Maybe children who travelled by car came from wealthier homes and so had healthier diets than the walkers? Maybe the walkers started out fitter at the beginning of the six year period and so couldn’t improve as much as “passive” children?

The best way to sort it out was to ask the paper’s lead author, Professor Palma Chillón Garzón at the unversity’s Department of Physical Education and Sport. Here’s his reply:

“It is correct that fitness increased lightly more among those who used passive modes than those who walked, but these differences are very small (fitness increased 1,289 in passive and 1,235 in walkers, and 1,488 in bikers).” [We assume a baseline fitness index of 1000 at the start of the six year period.]

So how does he explain the apparent fitness advantages of passive travel relative to walking?

“… there other variables that affect fitness like genetics, physical activity in the leisure time…etc.  For this reason, maybe young people who use passive modes to school might practice more physical activity in the leisure time than those who walked to school.”

The upshot is that the research set out to quantify the fitness improvements, not to explain the reasons. That’s another task. Who’s going to do it?

In the meantime, the more children who cycle to school, the better. Unfortunately, parents from different parts of the UK tweeted that their children’s schools didn’t allow them to cycle, even when staff are themselves cyclists.

Among the replies to the original tweet, one question remains unanswered: what proportion of children live within cycling distance of schools in southwest Pittsburgh? Any answers? Has that figure been worked out for any school? Cycle campaigners would find it very useful.

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Zombie stats and ghost papers

10/10/2012

It seems fitting to tell a little scary story as Halloween approaches.

They’re called zombie statistics – figures that should be dead and buried because they have no substance but they keep coming back to life.

Most of them don’t matter and are merely symptoms of everyone’s desire to believe in powerful myths.

But every so often there are zombie stats that are used to endorse serious messages and that’s just not right.

I came across one when trawling for data about helmets. The statistics page of the Bicycle Helmet Safety Institute cited figures published in a Children’s Safety Network pamphlet along with a link to download it.

One stood out. It said that “Head injuries accounted for 62.6 percent of bicycle fatalities” among children and youth age 0 to 19 in 2000 in the US.Zombie statistic in Children's Safety Network leaflet of 2008

It was clear, unequivocal and shocking.

I downloaded the pamphlet but was frustrated because it showed the statistic came from an unpublished paper.

Is this a real paper or a ghost?

So I contacted the author of the “unpublished paper”, Eduard Zaloshnja.

Eduard replied promptly and disarmingly honestly – sayng that no such paper existed, only a set of data he’d produced for the Children’s Safety Network.

So I asked for a copy of the data set but Eduard had lost it some years before when his hard drive crashed. Hmm, the origins of the startling figure showing the awful truth about head injuries killing a nation’s young cyclists was proving elusive.

Of course, it was reasonable to assume that the Children’s Safety Network, whch had commssioned Eduard’s research, would have a back-up of his data so I asked for a copy.

Two weeks passed.

Then the Library Assistant in the Network’s Education Development Center wrote to say they didn’t have a copy “since the paper is not yet published” and she apologised for the inconvenience.

Within two more weeks the Children’s Safety Network published a new, expanded, brochure and you can still download it here if you’re quick. The zombie statistic seemed to have been vanquished – at least, it doesn’t make an appearance.

Yet, eerily, the new pamphlet still contains a reference to Eduard’s unpublished paper, even though he says he never wrote such a paper and created only data which, unfortunately, disappeared several years ago when his computer crashed. How strange.

I guess the repeated reference to Eduard’s ghost paper might simply be a proof-reader’s error. More worrying, though, is the continued publishing of the zombie statistic on the Bicycle Helmet Safety Institute’s page.

They were told more than a year ago that, as neither Eduard nor the Children’s Safety Network could confirm the frightening data, it would be sensible to remove it from their Statistics page.

Spookily, it’s still there and it’s still a little scary – not because it’s true but because it can’t be substantiated. I hope it goes away soon.

25 days to go

08/10/2012

It’s been a long time coming but it’s almost there. Cycling Science by Max Glaskin

In 25 days my book on Cycling Science is due to be published. It occupied me for almost a year and, at times, it was not a comfortable journey. Finding science relevant to cycling that can also be illustrated with detailed infographics was a new challenge for someone used to dealing only with words, not illustrations. For instance, how can inertia, a fundamental influence on cycling, be illustrated clearly and easily? If you have an answer, please do send it via the Comment option below.

Nevertheless, by scouring the academic journals it was possible to pull together several hundred pieces of research that deserved to be explained clearly in words and graphics so that cyclists can understand better how they work with their bikes. Some of the science and data may be familiar to the keenest but the book covers such a wide spectrum, from environment and physiology to aerodynamics and technology that it’s likely more than 90% will be new information to most readers.

I finished work on the book in July 2012, after which my editors (seven at the last count) spent some time preparing it for printing. So I haven’t yet seen it and wait expectantly and nervously for the first advance copy. Although there is a pile of early page layouts stacked at the end of my desk, I know that whole spreads may have changed entirely and many, many tiny details tweaked.

This blog is an open continuation of the book. There are items of science research relevant to cycling that are published almost daily somewhere in the world. I’ve been tweeting them (@cyclingscience1) as often as possible so that they become known to an audience outside the universities and research labs. Every so often I add a short item to my Facebook page (Cycling Science).

This blog, thouygh, is meant to broaden the conversation, to receive feedback about the book, to hear directly from scientists and to disseminate and discuss the latest findings. If it works, it should be a lively read. If it doesn’t, well, I’ll just get on my bike and I’d suggest that you do, too.

Max Glaskin