Researchers in the US found that brief vigorous exercise can reduce cellular aging by preventing the shortening of telomeres due to stress.
You can read about the University of California San Francisco (UCSF) study in a paper published online in the open access journal PLoS ONE on 26 May.
Co-lead investigator, Dr Elissa Epel, an associate professor in the UCSF Department of Psychiatry, said in a statement that:
"Telomere length is increasingly considered a biological marker of the accumulated wear and tear of living, integrating genetic influences, lifestyle behaviors, and stress."
"Even a moderate amount of vigorous exercise appears to provide a critical amount of protection for the telomeres," said Epel.
Telomeres are protective strips of DNA that cap the ends of chromosomes and stop them unraveling, not unlike the plastic sheaths on the ends of shoelaces.
They were discovered by a group of 2009 Nobel Laureates that included Dr Elizabeth Blackburn, a co-author of the current paper.
There is also growing evidence that short telomeres are linked to several health problems, including diabetes and coronary heart disease, as well as early death.
The researchers built on previous UCSF-led studies that found psychological stress causes overall wear and tear in the body at a deep level in cells by promoting cell aging through shortening telomere length. However, as Blackburn noted:
"We are at the tip of the iceberg in our understanding of which lifestyle factors affect telomere maintenance, and how."
But, with this new study, it appears some of the iceberg is revealed, in that Epel, Blackburn and colleagues found that brief exercise, a modifiable lifestyle factor, buffers the telomere-shortening effect of stress.
They discovered that even as little as 42 minutes of vigorous exercise over a 3-day period, similar to levels recommended by federal health authorities in the US, seems to protect individuals from the effects of stress by reducing its effect on telomere length.
The US Centers for Disease Control and Prevention (CDC) recommends that adults undertake 75 minutes of vigorous, or 150 minutes of moderate activity, plus weight-bearing exercise, every week. For children and adolescents they recommend 90 minutes a day.
For the study Epel, Blackburn and colleagues recruited 62 post-menopausal women, many of whom were caring for spouses or parents with dementia.
The women reported at the end of each day how many minutes of vigorous activity they had engaged in. Vigorous activity was defined as "increased heart rate and/or sweating".
In a separate assessment, the participants also reported their perceptions of life stress during the previous month. They also gave blood samples so the researchers could measure the telomere length of their immune cells.
The results confirmed earlier findings from research on premenopausal women that found psychological stress promoted immune cell aging through shortening of telomeres.
But when they analyzed the results for the highly stressed women in terms of sedentary and inactive participants (the active participants included all those who met or exceeded the federally recommended 75 minutes of vigorous exercise a week), they found only the sedentary high stress participants had shorter telomeres.
The active, high stress participants did not have shorter telomeres. In other words, it appears that high stress predicted shorter telomeres in the sedentary but not the active group.
The researchers suggested that for this group of older women, the CDC recommended level of vigorous exercise is enough to buffer the effect that psychological stress has on telomere length.
But they said these results now need to be confirmed with larger groups.
Lead author Dr Eli Puterman, a psychologist in the UCSF Department of Psychiatry, said:
"At this point, we have replicated previous findings showing a link between life stress and the dynamics of how cells age."
"Yet we have extended those findings to show that, in fact, there are things we can do about it. If we maintain the levels of physical activity recommended, at least those put forth by the CDC, we can prevent the unyielding damage that psychological stress may have on our body.''
Puterman also said they found the participants who reported more stress were also the ones who were less likely to exercise, which may be discouraging, but it offers an opportunity to find out why more vulnerable, stressed people don't exercise much and find ways to encourage them to do so.
The researchers are now planning a study where participants get to know their own telomere length to see whether this motivates them to change their habits and do more exercise, reduce stress and eat less processed red meat, lifestyle factors that have been linked to telomere length.
"The Power of Exercise: Buffering the Effect of Chronic Stress on Telomere Length."
Eli Puterman, Jue Lin, Elizabeth Blackburn, Aoife O'Donovan, Nancy Adler, Elissa Epel.
PLoS ONE, 5(5): e10837, published online 26 May 2010.