Paul Biedermann of Germany (C) prepares prior to a men's 4x200m freestyle relay heat at the Aquatics World Championships in Kazan, Russia, August 7, 2015. REUTERS/Michael Dalder

Paul Biedermann of Germany prepares prior to a men's 4x200m freestyle relay heat at the Aquatics World Championships in Kazan, Russia, August 7, 2015. REUTERS/Michael Dalder

Silver medallist China's Sun Yang, gold medallist Britain's James Guy and bronze medallist Germany's Paul Biedermann (L-R) celebrate after the men's 200m freestyle final at the Aquatics World Championships in Kazan, Russia, August 4, 2015. REUTERS/Michael Dalder

Germany's Paul Biedermann poses with his bronze medal after the men's 200m freestyle final at the Aquatics World Championships in Kazan, Russia, August 4, 2015. REUTERS/Hannibal Hanschke

Paul Biedermann of Germany displays his bronze medal after the men's 200m freestyle final at the Aquatics World Championships in Kazan, Russia August 4, 2015. REUTERS/Stefan Wermuth

Paul Biedermann of Germany looks on after competing in the men's 200m freestyle semi-final at the Aquatics World Championships in Kazan, Russia, August 3, 2015. REUTERS/Hannibal Hanschke

Paul Biedermann of Germany swims in a men's 200m freestyle heat during the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Stefan Wermuth

Paul Biedermann of Germany swims in a men's 200m freestyle heat during the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Stefan Wermuth

Paul Biedermann of Germany reacts after a men's 200m freestyle heat during the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Hannibal Hanschke

Paul Biedermann of Germany swims in a men's 200m freestyle heat during the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Hannibal Hanschke

Paul Biedermann of Germany prepares before the men's 200m freestyle heats at the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Michael Dalder

Paul Biedermann of Germany swims during the men's 200m freestyle heats at the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Michael Dalder TPX IMAGES OF THE DAY

Paul Biedermann of Germany swims during the men's 200m freestyle heats at the Aquatics World Championships in Kazan, Russia August 3, 2015. REUTERS/Michael Dalder

Team Germany's Yannick Lebherz, Paul Biedermann, Robin Backhaus and Clemens Rapp (L-R) pose with medals after winning the men's 4x200m freestyle final at the European Swimming Championships in Berlin August 23, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Team Germany's Yannick Lebherz, Paul Biedermann, Robin Backhaus and Clemens Rapp (L-R) pose with medals after winning the men's 4x200m freestyle final at the European Swimming Championships in Berlin August 23, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Team Germany's Paul Biedermann swims to win in the men's 4x200m freestyle final at the European Swimming Championships in Berlin August 23, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Team Germany's Paul Biedermann, Yannick Lebherz, Robin Backhaus and Clemens Rapp (L-R) celebrate after winning the men's 4x200m freestyle final at the European Swimming Championships in Berlin August 23, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Team Germany's Paul Biedermann (2L), Yannick Lebherz (L), Robin Backhaus (R) and Clemens Rapp celebrate after winning the men's 4x200m freestyle final at the European Swimming Championships in Berlin August 23, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Silver medallist Paul Biedermann of Germany poses with medal after the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Gold medallist Velimir Stjepanovic of Serbia and silver medallist Paul Biedermann of Germany (R) pose with medals after the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Bronze medallist Yannick Agnel of France, gold medallist Velimir Stjepanovic of Serbia and silver medallist Paul Biedermann of Germany (L-R) pose with medals after the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts to his second place in the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts to his second place in the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts to his second place in the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims to place second in the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims to place second in the men's 200m freestyle final at the European Swimming Championships in Berlin August 20, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany greets Velimir Stjepanovic of Serbia (L) after the men's 200m freestyle semi-final at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany competes in the men's 200m freestyle semi-final at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING TPX IMAGES OF THE DAY)

Paul Biedermann of Germany prepares before the men's 200m freestyle semi-final at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts after the men's 200m freestyle semi-final at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany prepares before the men's 200m freestyle semi-final at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING TPX IMAGES OF THE DAY)

Paul Biedermann of Germany prepares to compete in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany prepares to compete in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany prepares to compete in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany prepares to compete in the men's 200m freestyle heats at the European Swimming Championships in Berlin August 19, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts after the preliminary heats of the men's 400m freestyle event at the European Swimming Championships in Berlin August 18, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany prepares to swim in the preliminary heats of the men's 400m freestyle event at the European Swimming Championships in Berlin August 18, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims in the preliminary heats of the men's 400m freestyle event at the European Swimming Championships in Berlin August 18, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany swims in the preliminary heats of the men's 400m freestyle event at the European Swimming Championships in Berlin August 18, 2014. REUTERS/Michael Dalder (GERMANY - Tags: SPORT SWIMMING)

Gold medallist Paul Biedermann of Germany poses during the award ceremony for the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Gold medallist Paul Biedermann of Germany poses during the award ceremony for the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Gold medallist Paul Biedermann (C) of Germany poses next to silver medallist Hao Yun (L) of China and bronze medallist Mads Glaesner of Denmark during the award ceremony for the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Gold medallist Paul Biedermann (C) of Germany poses next to silver medallist Hao Yun (L) of China and bronze medallist Mads Glaesner of Denmark during the award ceremony for the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany waves during the award ceremony for the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany celebrates winning the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany celebrates winning in the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany competes in the men's 400m freestyle final during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany reacts after competing at men's 400m freestyle heats during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany competes at men's 400m freestyle heats during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany competes at men's 400m freestyle heats during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany competes at men's 400m freestyle heats during the FINA World Swimming Championships in Istanbul December 14, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Germany's team members Paul Biedermann, Dimitri Colupaev, Christoph Fildebrandt and Yannick Lebherz celebrate their third place during the award ceremony for the men's 4x200m freestyle final during the FINA World Swimming Championships in Istanbul December 13, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Paul Biedermann of Germany (bottom) looks at the scoreboard after competing at men's 4x200m freestyle heats during the FINA World Swimming Championships in Istanbul December 13, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Silver medalist Paul Biedermann of Germany, gold medalist Ryan Lochte of the U.S. and bronze medalist Conor Dwyer of the U.S. display their medals after the men's 200m freestyle final during the FINA World Swimming Championships in Istanbul December 12, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

Ryan Lochte of the U.S. reacts after he won the men's 200m freestyle final next to Paul Biedermann of Germany (R) during the FINA World Swimming Championships in Istanbul December 12, 2012. REUTERS/Murad Sezer (TURKEY - Tags: SPORT SWIMMING)

(From L to R) Britain's Robbie Renwick, Ryan Lochte of the U.S., South Korea's Park Tae-hwan, China's Sun Yang, France's Yannick Agnel and Germany's Paul Biedermann are seen underwater as they swim during the men's 200m freestyle final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT SWIMMING OLYMPICS)

Germany's Paul Biedermann (L) shakes hands with Cayman Islands' Brett Fraser after their men's 200m freestyle semi-finals during the London 2012 Olympic Games at the Aquatics Centre July 29, 2012. REUTERS/Tim Wimborne (BRITAIN - Tags: SWIMMING SPORT OLYMPICS)

(From top to bottom) Germany's Paul Biedermann, Russia's Danila Izotov, Switzerland's Dominik Meichtry, Germany's Clemens Rapp and Italy's Marco Belotti are seen underwater as they compete in their men's 200m freestyle heats during the London 2012 Olympic Games at the Aquatics Centre July 29, 2012. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT SWIMMING SPORT OLYMPICS)