English athlete Roger Bannister among a crowd at Oxford after becoming the first person in the world to run a mile in under 4 minutes (3:59.4). Norman Potter/Getty Images hide caption

toggle caption Norman Potter/Getty Images

Carol Downing is still haunted by memories of last year's marathon. But she's excited about reuniting with other survivors. Michael Dwyer/AP hide caption

toggle caption Michael Dwyer/AP

Runners train in Ngong, Kenya, in 2012. The country has produced the world's best distance runners for decades, and most belong to the Kalenjin people. Michael Steele/Getty Images hide caption

toggle caption Michael Steele/Getty Images

Researchers say our brains are probably wired from an evolutionary sense to encourage running and high aerobic activities. Above, a man runs past the Sydney Harbour Bridge on April 22. Ryan Pierse/Getty Images hide caption

toggle caption Ryan Pierse/Getty Images

Shots - Health News

'Wired To Run': Runner's High May Have Been Evolutionary Advantage

Endurance athletes sometimes say they're "addicted" to exercise, and research suggests that may not be an overstatement.

Listen Loading… 4:51
  • Playlist
  • Download
  • Embed
    <iframe src="http://www.npr.org/player/embed/151936266/152175552" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">

NPR thanks our sponsors

Become an NPR sponsor