Olympic swimmers in more than half of the pool in Rio might have been boosted by a current, American scientists believe.
A team of researchers says it's found a trend of athletes swimming from lanes four to eight dominating the 50m freestyle competition.
Joel Stager, director of Indiana University's Counsilman Center for the Science of Swimming, told the Wall Street Journal that swimmers in those lanes consistently posted better times through heats and finals.
Of the eight men and eight women in the 50m freestyle finals, all but one swam in lanes four to eight through qualification.
Stager also says swimmers who moved in heats from lanes five to eight to lanes one to four became slower.
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"It's a big deal. This is horrific," he told the journal.
Five of the six male and female medallists in the freestyle sprint came from lanes four to eight.
The exception was American Anthony Ervin, who won gold from lane three.
According to Stager, the problem stems from a design flaw which creates a current in the pool.
He found a similar effect at the 2013 world championships in Barcelona, co-authoring a paper published in the Medicine and Science in Sports and Exercise journal that concluded a current influenced the 50m races.
Both pools were built by the same company, Mrytha.
However, Myrtha chairman Trevor Tiffany told the Wall Street Journal that a large jug was used to test the Rio pools for currents during and after races.
"The tests were conclusive that there was no movement of water," he said.
"If we saw there was a current, we'd have done something about it."
Officials from swimming's governing body FINA are reportedly investigating the analysis.
