THANK YOU FOR VISITING SWEATSCIENCE.COM!
As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.
- Alex Hutchinson (@sweatscience)
Just noticed this study published online ahead of print in the journal Drug Testing and Analytics, which suggests that both performance-enhancing drugs and hard training “may alter the expression of specific genes involved in muscle and bone metabolism by epigenetic mechanisms, such as DNA methylation and histone modifications.” Cool, huh? This is why the “genetics versus training” debate is so irreducibly complicated: training can effectively change your genetics.
Recognition of the potential role of epigenetics has been gaining traction over the past few years. Here’s how a review paper on the genetics of elite athletic performance in the Journal of Physiology put it a few months ago:
[F]uture research might determine to what extent the changes that environmental factors can induce in gene expression during critical periods of prenatal and postnatal development (i.e. through epigenetic mechanisms) explain why some individuals reach the elite athletic status. For instance, elite Kenyan runners, who have dominated most distance running events in the last two decades, undergo stringent training regimens since childhood (running ~20 km/day) at high altitude (~2000 m), which might lead to unique environment–gene interactions.
So what are these “epigenetic mechanisms”? This article from Scientific American explains the most common mechanism:
The best-studied form of epigenetic regulation is methylation, the addition of clusters of atoms made of carbon and hydrogen (methyl groups) to DNA. Depending on where they are placed, methyl groups direct the cell to ignore any genes present in a stretch of DNA.
The SciAm article focuses on evidence that overweight mothers may pass the tendency to be overweight on to their children. What’s crucial is that this “inherited” trait isn’t encoded in DNA — instead, it’s how the DNA’s instructions are carried out that is altered. For example, there’s preliminary evidence that children born to an overweight mother before she undergoes gastric bypass surgery are more likely to become overweight when they grow up than their siblings born after the surgery [EDIT: see this AP story or this study for details]. If this was a simple genetic inheritance (i.e. through DNA), the surgery wouldn’t make any difference to inherited traits. Instead, it appears to be an epigenetic phenomenon.
Anyway, this is a topic I’m hoping to learn more about. On the surface, it seems to be a vindication of the old saying “The harder I work, the more talented I get.” I certainly don’t discount the obvious role of genetics in shaping ultimate athletic potential (particularly when we’re talking about the extremes represented by world champions and world record holders), but I do think many people still underestimate how much their body — and even their gene expression — can adapt to the demands they put on it.