Genetic research and exercise: reasons why Ellie is running her first marathon

In May this year I’ll be running my first marathon. Training is gruelling and involves running upwards of 40km a week, my legs ache for a significant amount of the time, and I’ve had to turn down Sunday brunch on more than one occasion – my excuse being “…but my long run is that day and I need to hit my weekly target!”

This has led a lot of people to ask me: “WHY are you doing this to yourself?”

I’ll tell you why: science.

Ellie (3)



A recent study suggests that a lack of exercise can have significant effects on our biological aging. Researchers at the University of California, San Diego have observed a significant association between physical activity and telomere length in a group of 1,481 elderly women.

In case, like me, you’re not a biologist, I’ll give you a quick explanation about telomeres. They’re tiny caps on the end of your chromosomes, almost like the aglets on a shoelace. They have a key protective function – to keep your chromosomes from deteriorating. Unfortunately, as our cells divide our telomeres shorten, until they become completely degraded and the cell is no longer able to divide at all. As a result, we can use telomeres as an indicator of biological age – since the cells in older individuals will have divided more times, and therefore have shorter telomeres.

Telomere length can also be affected by a huge number of environmental and genetic factors. This means that some people can be the same age chronologically, but appear ‘older’ biologically. The team at UC San Diego have demonstrated this. In essence, their research found that women who sit for more than 10 hours a day, and don’t do much exercise to compensate for this, have cells that are biologically older by 8 YEARS than women who are less sedentary, as shown by their telomeres. So basically: exercise slows down your biological aging. Which is nice.

“some people can be the same age chronologically, but appear ‘older’ biologically”

By now, you’re probably thinking: Ellie, why are we talking about this? Sure, it’s interesting, but this is a mental health blog, not a post for the Telomere Appreciation Society.

Well, it turns out that our telomere length and biological age might just be intertwined with our mental health, in ways that I personally hadn’t expected.

More recently, research by Dr. Timothy Powell’s team here at King’s found that genes involved in biological aging might also have an effect on the development of depression. Essentially, there are genetic variants that prime individuals to (biologically) age quicker, leading to shorter telomeres. Powell’s team identified one such genetic variant that also increases risk for developing childhood-onset depression. So, children who are genetically predisposed to have shorter telomeres, and thus an increased rate of biological aging, may also be at higher risk of developing depression at a young age.

This could have huge implications, as it suggests that biological ageing could play a role in the development of depression in some children. The researchers also suggest that based on this, we could try to slow down biological aging rates, and reduce the risk of some children developing depression, using a combination of stress management techniques, diet and, you guessed it…exercise.

So does that mean that increasing your exercise could, in a circular manner, decrease your risk of developing depression?

Obviously, you have to take this kind of research with a pinch of salt:

  1. Telomeres are not a direct measure of aging.
  2. The development of depression is linked to a multitude of genetic and environmental factors.
  3. We can’t draw any causational relationships from this research.

However, there’s a lot of research out there already (e.g. this paper on the positive effects of exercise for patients with general anxiety disorder) linking exercise with increased quality of mental health. It’s no secret that exercising a bit more is good for us – and it now it seems that there’s even more evidence that exercise could reduce our risk of developing mental health conditions, like depression.

“It’s no secret that exercising a bit more is good for us”


SO, when I’m next dragging myself out on a 25km training run, I’ll be helped along by the idea that there’s some sort of scientific reason behind it.