How Much Exercise Keeps Your Cells Young?

Telomere length, a marker of “biological ageing”, responds to relatively high levels of physical activity.

One of the buzziest words in health six or seven years ago was “telomere”, which is the protective cap on the ends of your chromosomes – like the plastic tips on shoelaces, according to one analogy. Every time your cells replicate, they lose a bit of this protective cap, until the telomeres get so short that the cell can’t replicate properly anymore, which is why telomere length is considered one marker of biological age.

The good news for runners is that, starting in around 2010, a series of studies has suggested that endurance exercise preserves telomere length as you get older. For example, a 2013 study of ultrarunners found that their telomeres were 11 per cent longer, corresponding to a 16-year decrease in biological age, than non-running controls.

But how much running do you have to do to see telomere benefits? Is this one of those cases where a little is all you need, or do you have to put it some serious mileage?

Researcher Larry Tucker, of Brigham Young University in the US, has published three recent studies on telomere length, each of which offers some interesting insights. The first, which was presented earlier in June this year at the American College of Sports Medicine conference and published in Preventive Medicine, tackles the question of exercise dose.

Tucker analysed data from almost 6000 adults in the National Health and Nutrition Examination Survey, comparing their telomere lengths (as determined during a DNA test) and their self-reported physical activity patterns. Those who exercised did indeed have longer telomeres—but only in the group that exercised the most. Here’s what telomere length looked like:

Telomere length.

Alex Hutchinson

On the left axis is telomere length, in units of “base pairs”. The average telomere length in this group was 5828 base pairs long, and the lengths were 15.6 base pairs shorter for each additional year of age.

On the right axis, I’ve plotted the difference in biological age, assuming that each year corresponds to 15.6 base pairs. The high-physical-activity group’s cells appear almost nine years younger than the sedentary group’s cells, after adjusting for differences in demographics and lifestyle.

Intriguingly, there’s no significant difference in telomere length between the sedentary, low-physical-activity, and moderate-physical groups. To get the benefits, you need to be in the highest third of activity. What does that correspond to? Based on the study, Tucker pegs the threshold at around 30 minutes of jogging five days a week for women, and 40 minutes five days a week for men.

That’s not all Tucker has to say on the topic. He also published an analysis of similar data in the Journal of Nutrition, Health, & Aging looking at consumption of nuts and seeds. More is better: those who consumed about 3 per cent of their total energy intake in the form and nuts and seeds were one year “younger” by telomere length.

And finally, he published a further analysis in Nutrition & Metabolism (freely available online), this one on the effects of caffeine and coffee. In this case, the results are a little trickier to parse. The short version: caffeine makes your telomeres shorter (which is bad) but coffee makes them longer (which is good).

There’s previous evidence that caffeine may interfere with DNA repair, which disrupts chromosomes. On the other hand, coffee itself (even decaffeinated) has anti-inflammatory properties that could be beneficial. So which effect wins? That depends on various factors, like how strong your coffee is.

Overall, for every 100 milligrams of caffeine the subjects consumed daily, their telomeres were 35.4 base pairs shorter (after adjusting for confounders including coffee consumption).

In contrast, for every 100 grams of coffee the subjects consumed daily, their telomeres were 15.0 base pairs longer (after adjusting for confounders including caffeine consumption).

On days other than Mondays and Tuesdays  a Grande-sized Starbucks breakfast blend has about 300 milligrams of caffeine, so you’re trading off a 68-base-pair gain from the coffee against a 106-base-pair loss from the caffeine. At that level of daily caffeine consumption, it doesn’t seem like a big deal; but if your consumption is way higher, then any effects would be magnified.

Overall, it should be noted, large epidemiological trials have tended to find generally neutral or positive health effects of coffee (though there’s some evidence that genes for caffeine metabolism may influence the balance of positive and negative effects in individuals). But this new data bolsters the case that it’s coffee, rather than caffeine itself, that may be good for you.

In the end, telomere research, though it earned a Nobel Prize in 2009, is still a relatively young field. There’s a long way to go before we can be confident about what telomere length really tells us and how to change or protect it. But for now, it appears that running is a good place to start.


Subscribe to Runner's World

Related Articles