Aaron Peirsol of the U.S. swims during his heat of the men's 200m backstroke at the Pan Pacific 2010 swimming championships in Irvine, California, August 20, 2010. Peirsol did not qualify for the finals. REUTERS/Christinne Muschi (UNITED STATES - Tags: SPORT SPORT SWIMMING) 

Aaron Peirsol of the U.S. looks back at his time in the men's 200m backstroke at the Pan Pacific 2010 swimming championships in Irvine, California, August 20, 2010. Peirsol did not qualify for the finals. REUTERS/Christinne Muschi (UNITED STATES - Tags: SPORT SWIMMING) 

Aaron Peirsol (L) of the U.S. celebrates with Hayden Stoeckel of Australia after Peirsol won the men's 100m backstroke at the Pan Pacific 2010 swimming championships in Irvine, California August 18, 2010. REUTERS/Christinne Muschi (UNITED STATES - Tags: SPORT SWIMMING) 

Aaron Peirsol of the U.S. looks at the scoreboard after winning the men's 100m backstroke at the Pan Pacific 2010 swimming championships in Irvine, California August 18, 2010. REUTERS/Christinne Muschi (UNITED STATES - Tags: SPORT SWIMMING) 

Aaron Peirsol of the U.S. comes off the starting blocks during the start of the men's 100m backstroke at the Pan Pacific 2010 swimming championships in Irvine, California, August 18, 2010. REUTERS/Lucy Nicholson (UNITED STATES - Tags: SPORT SWIMMING) 

The start of the men's 100m backstroke final, won by Aaron Peirsol (second from bottom) at the Pan Pacific 2010 swimming championships in Irvine, California, August 18, 2010. REUTERS/Christinne Muschi (UNITED STATES - Tags: SPORT SWIMMING) 

World record holder Aaron Peirsol competes during heat 15 of the Men's 100m Backstroke event at the U.S. National Swimming Championships in Irvine, California August 4, 2010. REUTERS/Alex Gallardo (UNITED STATES - Tags: SPORT SWIMMING) 

World record holder Aaron Peirsol competes during heat 15 of the Men's 100m Backstroke event at the U.S. National Swimming Championships in Irvine, California August 4, 2010. REUTERS/Alex Gallardo (UNITED STATES - Tags: SPORT SWIMMING) 

Aaron Peirsol (L), Eric Shanteau and Michael Phelps (R) of the U.S. relay team celebrate their gold medals after the men's 4 X 100m medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Laszlo Balogh (ITALY SPORT SWIMMING) 

Michael Phelps (2nd R) of the U.S. celebrates on the podium with team mates Aaron Peirsol (L), Eric Shanteau and David Walters after the men's 4 X 100m medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Michael Phelps (2nd R) of the U.S. laughs on the podium with team mates Aaron Peirsol (L), Eric Shanteau and David Walters after the men's 4 X 100m medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Michael Phelps (2nd R), Aaron Peirsol (L), Eric Shanteau and David Walters of the U.S. listen national anthem after the men's 4 X 100m medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Eric Shanteau (L), Aaron Peirsol (C) and Michael Phelps of the U.S. react during the men's 4x100 medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Eric Shanteau (L), Aaron Peirsol (C) and Michael Phelps of the U.S. react during the men's 4x100 medley relay swimming final at the World Championships in Rome August 2, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Gold medallist Aaron Peirsol of the U.S. poses on the podium after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Gold medallist Aaron Peirsol (C) of the U.S. poses on the podium with silver medallist Ryosuke Irie (L) of Japan and bronze medallist Ryan Lochte of the U.S. after the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Gold medallist Aaron Peirsol of the U.S. poses on the podium after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. is embraced by his mother after winning gold and setting a new world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes to win a gold medal in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Stefano Rellandini (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol (L) of the U.S. reacts after winning and setting a world record as Ryosuke Irie of Japan watches after the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Stefano Rellandini (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. (L) celebrates with Ryosuke Irie of Japan after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Wolfgang Rattay (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates after winning and setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates setting a world record next to Ryosuke Irie (R) of Japan in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Laszlo Balogh (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. (L) reacts beside Ryosuke Irie of Japan after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Laszlo Balogh (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. (L) reacts beside Ryosuke Irie of Japan after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING IMAGES OF THE DAY) 

Aaron Peirsol of the U.S. competes to set a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. celebrates a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING IMAGES OF THE DAY) 

Aaron Peirsol of the U.S. competes in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING IMAGES OF THE DAY) 

Aaron Peirsol of the U.S. reacts after setting a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes to set a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING IMAGES OF THE DAY) 

Aaron Peirsol of the U.S. competes to set a world record in the men's 200m backstroke swimming final at the World Championships in Rome July 31, 2009. REUTERS/Max Rossi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 200m backstroke swimming heats at the World Championships in Rome July 30, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 200m backstroke swimming heats at the World Championships in Rome July 30, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 200m backstroke swimming heats at the World Championships in Rome July 30, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke semi-finals at the World Championships in Rome July 27, 2009. REUTERS/Stefano Rellandini (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Alessandro Bianchi (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Stefano Rellandini (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. competes in the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING) 

Aaron Peirsol of the U.S. lifts his goggles after the men's 100m backstroke swimming heats at the World Championships in Rome July 27, 2009. REUTERS/Tony Gentile (ITALY SPORT SWIMMING)