Allegations have surfaced that Olympic swimmers on one side of the pool in Rio were advantaged because of a current.

Three scientists have suggested a current boosted 50m competitors in the higher-numbered lanes of the eight-lane pool. The same scientists, led
by Joel Stager, director of Indiana University's Counsilman Center for the Science of Swimming, have previously said a current influenced 50m races at the 2013 world championships in Barcelona.

The Wall Street Journal reported that the scientists found trends to suggest the pool in Rio favoured one side in the one length sprint race.

Out of eight men and eight women who qualified for the 50m finals, all but one swam in lanes 4 through 8. On top of that, athletes who swam in lanes 5 through 8 during preliminaries or semifinals and moved to lanes 1 through 4 for later heats got slower.

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They posted times about 0.5 per cent slower in the final, even though swimmers tend to get faster in the later rounds.

Of the three male and three female medallists in the 50m freestyle finals, five swam in lanes 4 through 8. The exception was American Anthony Ervin, who won the 50-free gold medal swimming in lane 3. Pernille Blume of Denmark won the women's 50 free in lane 4.

"It's a big deal. This is horrific," Stager was quoted as saying in the Wall Street Journal.

Trends also emerged in the longer 800m and 1500m races.

Swimmers in lanes 1 through 3 were as much as 0.6 seconds slower when swimming towards the starting blocks than going in the other direction. Swimmers in lanes 6 through 8 showed the reverse, logging faster times while moving toward the starting blocks than they did away from themOfficials at Fina, swimming's world governing body, said they were reviewing the analysis.