![Close swim: The women's 50m freestyle semi-final in Rio.](/web/20160902011648im_/http://www.smh.com.au/content/dam/images/g/r/7/3/7/d/image.related.wideLandscape.460x259.gr71oq.png/1472775762682.jpg)
Did some swimmers have an unfair advantage in Rio?
A few years ago, researchers from Indiana University discovered a disturbing pattern at the 2013 Swimming World Championships in Barcelona. According to the lap-time data, athletes assigned to the outer lanes of the pool were consistently swimming faster in one direction than the other.