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Stand up for health!

by on 2014/10/03

Nobody would argue against the invitation of standing up for health, if only that was it. Instead the title of a scientific paper published in The British Journal of Sports Medicine went a bit further: Stand up for health—avoiding sedentary behaviour might lengthen your telomeres: secondary outcomes from a physical activity RCT in older people. Such a title can only invite bad science reporting. Telomeres are a favourite target for media hype as they provide many attractive characteristics to stimulate a writer’s imagination.

Telomeres are stretches of DNA sequence repeats found at the end of each chromosome, which function as protective caps. Every time cells divide, telomeres get shorter until signalling the cell to die. Therefore telomeres are an indicator of the ageing process. A considerable amount of research is directed towards examining how lifestyle and life events might impact on telomere length, and consequently in prolonging or shortening life.

The current study was designed to assess how exercising might slow down telomere shortening. The methodology presented many of the limitations of other studies in this field: small sample size, even smaller informative subgroups and very weak statistics. The study reported no effects of exercising on telomere length, but proposed an even simpler formula: the more time spent sitting, the shorter the telomeres. It is not difficult to see how such a story has all the ingredients to be picked up by the media to offer a simple remedy for a longer and healthier life. As often happens, press releases (in this case by the host institution of one of the leading authors, Prof Mai-Lis Hellénius at the Karolinska Institute, and also from the journal), were aimed at promoting the sensational aspects of the study rather than the scientific content, while admitting the study was very small. Among the most colourful headlines that followed these press releases were: “Sofa, so bad – why sitting down cuts short your life” and “How standing might be the best anti-ageing technique”.

Not all media reports of the study promised the elixir of life, and a piece in Forbes by Steven Salzberg does an excellent job at looking at the flaws in the study design by examining the original paper. In particular, Salzberg explains how the association between time spent standing and telomere length was found in a very small group of 12 individuals, and further that the weak association appeared to driven by two outliers (see Figure 2B of original paper).

I certainly do not want to discourage spending more time standing and exercising, but on the basis of this study it is not possible to demonstrate that such lifestyles protect the telomeres in particular to give us longer life. In general, it is very advisable to be aware of these issues any time we see stories about telomeres in the media. Let’s stand up for health, but also for good science reporting.

Sjögren, P. et al.(2014). Stand up for health—avoiding sedentary behaviour might lengthen your telomeres: secondary outcomes from a physical activity RCT in older people. British Journal of Sports Medicine. DOI: 10.1136/bjsports-2013-093342

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