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A study looking at an association between levels of activity of overweight individuals and telomere length was published in the British Journal of Sports Medicine.
Prof Chris Pepper, Professor of Haematology, Cardiff University School of Medicine, said:
“The sample size is too small to draw any firm conclusions about the influence of exercise (or not sitting) on general health. Of course, we would anticipate that regular physical exercise would be associated with health benefits and potentially even longevity in an ageing population. However, the rationale for measuring the telomere length of blood cells in this context is unclear. In any event, there was no significant change in telomere length profiles in either group so the telomere story is somewhat of a red herring here.”
Dr David Clancy, Lecturer in the Division of Biomedical and Life Sciences, Lancaster University, said:
“Few people believe telomere shortening is a significant cause of ageing because the evidence just isn’t there, however telomere shortening may, at least partly, result from processes that do actually cause ageing. So they are sometimes used as a biomarker of ageing.
A biomarker of ageing is, ideally, a measure which indicates how much of your life you have already lived. The popularity of telomere length as a biomarker comes partly from a time when telomeres were thought to be linked more strongly to ageing, and as predictors aren’t terribly good. However several environmental and other factors which are associated with shorter or longer life are also associated with shorter or longer telomeres so in this study they were used as markers of ageing-related damage.
Borderline-significant telomere shortening associated with increased exercise was found in both exercise and control groups, a result opposite to that seen in previous studies. However unlike previous studies the subjects here were 68 years old and overweight-obese. Perhaps substantial increased activity induces damage in such subjects.
The statistically significant result, that reduced sitting time was associated with telomere lengthening, would need repeating because the number of participants was only 12, as the authors state, and the result was seen only in the intervention group, not the control group.
There is not the evidence that telomere length is causally associated with ageing, and associations with parameters of ageing and health, both in humans and other mammals, are not generally strong. However there is substantial evidence that reduced sitting time has beneficial effects on a range of health-related measures and is clearly a good idea.”
Prof Ilaria Bellantuono, Professor of Musculoskeletal Ageing, University of Sheffield, said:
“While the findings are intriguing they are inconclusive at this stage and a larger study needs to be conducted. As the authors emphasize the sample is small and the data rely only on one significant correlation between increased telomere length and decreased time spent sitting. Considering that if an individual is not seated they are highly likely to be doing some sort of movement I would have expected to find a significant correlation between increased number of steps taken and increased telomere length. The fact that this is not the case makes me question the validity of this study.”
‘Stand up for health – avoiding sedentary behaviour might lengthen your telomeres: secondary outcomes from a physical activity RTC in older people’ by Sjögren et al. published in the British Journal of Sports Medicine on Wednesday 3rd September.
Declared interests
Prof Ilaria Bellantuono is a grant holder of the funding for the MRC/Arthritis Research-UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA)