Recent research showed that strenuous jogging is actually as likely to shorten your lifespan as taking no exercise – except of course that it doesn’t show this at all!
A study published by the American College of Cardiology was widely written up in the press last week with headlines like –
- "Training very hard 'as bad as no exercise at all'" – BBC News
- "Fast running is as deadly as sitting on couch, scientists find" – Daily Telegraph
- "When It Comes to Jogging, Easy Does It, Study Suggests"
Rather than being a warning against over doing it, these stories actually highlight the vital importance of experimental design. Enshrined in the rules of Good Clinical Practice is the importance of designing a trial so that the results are statistically valid.
The research was intended to investigate whether intensity of exercise has an effect on benefit – specifically, whether high-intensity physical exercise is healthy. Unsurprisingly, it revealed that those who took regular, moderate exercise had lower mortality rates than those who were totally sedentary.
However, the conclusion that got the press excited was that those who took regular strenuous exercise actually had higher mortality rates. The cause of death was not recorded in the study – could it be that running that much raises your risk of a fatal traffic accident above the benefit of the exercise?
The study involved over 5,000 individuals, but only 36 (about 0.7%) fell into the strenuous activity category.
So how many of this group died in a ten year period? Two!
The reason that experimental design plays such a key role in Good Clinical Practice is partly to protect the participants – after all, no trial is completely risk free and so patients should not be put at risk unless there is a real potential benefit.
I can understand why yet another study showing that “exercise is good for you” wouldn’t have caused much of a media stir. People get bored of hearing the same old message and are keen to latch onto a new take on old advice.
This should serve as a warning – especially given that, with greater disclosure, research is open to scrutiny of those looking to find an interesting story, rather than increase scientific understanding.
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