Has Running Hit the Wall?

I have a new article in today's ScienceNOW:

Runners test the limits of human endurance. But a new study suggests that they may not have that much further to go.

To trim seconds off their times, runners continue to tweak their training and nutrition regimens. And as more of the world's population gets involved in world-class racing, the pool of potential record breakers grows. Researchers know the sky is not the limit. However, when they would reach the peak has not been clear....

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