Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Emily Singer

A View from Emily Singer

Is Evolution Selecting for Endurance Runners?

Genetic variation found in elite long-distance athletes boosts efficiency of muscle metabolism.

  • September 9, 2007

Trainers and athletes already know that sprinters and marathon runners have very different muscles. Sprinters tend to have a preponderance of fast-twitch muscle fibers, which generate short bursts of strength, while endurance athletes have more slow-twitch fibers, which take longer to fatigue.

New research shows that a genetic variation found more often in long-distance athletes seems to make fast-twitch muscle fibers behave more like slow-twitch ones. The variation, known as R577X, completely knocks out a muscle protein expressed only in fast-twitch fibers. Mice genetically engineered to carry this variation had more efficient muscle metabolism and could run 33 percent farther before reaching exhaustion than their normal counterparts, according to findings published Sunday in Nature Genetics.

This variation also seems to confer an evolutionary advantage in humans. By analyzing the DNA sequence surrounding it, scientists found that is has been positively selected for in recent human history.

Want to go ad free? No ad blockers needed.

Become an Insider
Already an Insider? Log in.
More from Rewriting Life

Reprogramming our bodies to make us healthier.

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    Print + Digital Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

    Technology Review PDF magazine archive, including articles, images, and covers dating back to 1899

    10% Discount to MIT Technology Review events and MIT Press

    Ad-free website experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning print magazine, unlimited online access plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Print Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

  • Insider Online Only {! insider.prices.online !}*

    {! insider.display.menuOptionsLabel !}

    Unlimited online access including articles and video, plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

/3
You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.