Spain's Diego Ruiz falls during in the men's 1500m heats at the athletics event during the London 2012 Olympic Games on August 3, 2012 in London. AFP PHOTO / OLIVIER MORIN

France's Joris Daudet (L on the ground) and Nicholas Long of the U.S. (64) fall during the men's BMX quarter-final run at the London 2012 Olympic Games at the BMX Track in the Olympic Park August 9, 2012. REUTERS/Stefano Rellandini

China's Liu Xiang falls after hitting a hurdle in his men's 110m hurdles round 1 heat during the London 2012 Olympic Games at the Olympic Stadium August 7, 2012. REUTERS/Mark Blinch (BRITAIN - Tags: SPORT OLYMPICS SPORT ATHLETICS TPX IMAGES OF THE DAY)

Britain's Jennifer Pinches falls from the balance beam during the women's gymnastics team final in the North Greenwich Arena at the London 2012 Olympic Games July 31, 2012. REUTERS/Dylan Martinez (BRITAIN - Tags: SPORT GYMNASTICS OLYMPICS)

France's Ladji Doucoure jumps (L) while Bahamas' Shamar Sands (R) falls during the men's 110m hurdles heats at the athletics event during the London 2012 Olympic Games on August 7, 2012 in London. AFP PHOTO / GABRIEL BOUYS

Croatia's Tina Mihelic falls from her dinghy in the Laser Radial sailing class at the London 2012 Olympic Games, in Weymouth on August 3, 2012. AFP PHOTO / William WEST

North Korea's Rim Jong Sim smiles as she falls while competiting for the gold medal during the women's 69kg group A weightlifting event at The Excel Centre in London on August 1, 2012 during the London 2012 Olympic Games. AFP PHOTO / YURI CORTEZ

Croatia's centreback Miranda Tatari reacts after falling during the women's quarter-final handball match Spain vs Croatia for the London 2012 Olympics Games on August 7, 2012 at the Copper Box hall in London. AFP PHOTO/ JAVIER SORIANO

China's Liu Xiang (C) falls while competing in the men's 110m hurdles heats at the athletics event of the London 2012 Olympic Games on August 7, 2012 in London. AFP PHOTO / GABRIEL BOUYS

Chinese forward Zhu Fangyu bleeds during the men's preliminary round Groupe B basketball match Australia vs China of the London 2012 Olympic Games on August 2, 2012 at the basketball arena in London. Australia won 49-23. AFP PHOTO / MARK RALSTON

Angolan forward Felizarda Jorge falls during the Women's preliminary round group A basketball match of the London 2012 Olympic Games Turkey vs Angola on July 28, 2012 at the basketball arena in London. AFP PHOTO / MARK RALSTON

Competitors are involved in a collision during the men's BMX quarter-final run at the London 2012 Olympic Games at the BMX Track in the Olympic Park August 9, 2012. REUTERS/Stefano Rellandini (BRITAIN - Tags: OLYMPICS SPORT CYCLING)

Russia's Kseniia Afanaseva falls during her floor exercise during the women's gymnastics team final in the North Greenwich Arena at the London 2012 Olympic Games July 31, 2012. REUTERS/Mike Blake

Japan's Yoshiaki Oiwa falls from his horse Noonday de Conde while competing in the Eventing Cross Country equestrian event at the London 2012 Olympic Games in Greenwich Park, July 30, 2012. REUTERS/Eddie Keogh (BRITAIN - Tags: SPORT OLYMPICS EQUESTRIANISM)

A judge watches as Kohei Uchimura of Japan falls off the pommel horse during the men's gymnastics team final in the North Greenwich Arena during the London 2012 Olympic Games July 30, 2012. REUTERS/Phil Noble

U.S. gymnast Nastia Liukin falls on the uneven bars at the U.S. Olympic gymnastics trials in San Jose, California June 29, 2012. REUTERS/Mike Blake

Poland's Lukasz Zygadlo falls into an advertising hoarding during the men's quarter-final volleyball match between Poland and Russia in the 2012 London Olympic Games in London on August 8, 2012. AFP PHOTO/KIRILL KUDRYAVTSEV

US rider Brooke Crain is assisted after crashing during the BMX cycling seeding phase runs at the BMX venue in the Olympic Park, during the London 2012 Olympic games in London on August 8, 2012. AFP PHOTO/Carl de Souza

Denmark's Lasse Norman Hansen crashes during the London 2012 Olympic Games men's omnium 15km scratch race cycling event at the Velodrome in the Olympic Park in East London on August 5, 2012. AFP PHOTO /ODD ANDERSEN

Spain's Diego Ruiz (C) falls during in the men's 1500m heats at the athletics event during the London 2012 Olympic Games on August 3, 2012 in London. AFP PHOTO / OLIVIER MORIN

Latvia's Edzus Treimanis bleeds after crashing his bike during the men's BMX seeding run during the London 2012 Olympic Games at the BMX Track in the Olympic Park August 8, 2012. REUTERS/Cathal McNaughton

Destinee Hooker (C) of the U.S. falls during their women's quarterfinal volleyball match against Dominican Republic at Earls Court during the London 2012 Olympic Games August 7, 2012. REUTERS/Ivan Alvarado

Gabrielle Douglas of the U.S. falls during the women's gymnastics balance beam final in the North Greenwich Arena during the London 2012 Olympic Games August 7, 2012. REUTERS/Brian Snyder

China's Liu Xiang (R) falls as Poland's Artur Noga pulls up in the men's 110m hurdles round 1 heat at the London 2012 Olympic Games at the Olympic Stadium August 7, 2012. Liu crashed out of the heats in the 110 meters hurdles at the London Olympics on Tuesday in an echo of his injury-induced withdrawal from the same stage of the Beijing Games four years ago. REUTERS/David Gray (BRITAIN - Tags: OLYMPICS SPORT ATHLETICS)

Clarisse Cruz (R) of Portugal falls during her round 1 women's 3000m steeplechase heat during the London 2012 Olympic Games at the Olympic Stadium August 4, 2012. REUTERS/David Gray

Spain's Diego Ruiz falls during the men's 1500m round 1 event at the London 2012 Olympic Games in the Olympic Stadium August 3, 2012. REUTERS/David Gray

Spain's Alvaro Rodriguez falls during the men's 1500m round 1 event at the London 2012 Olympic Games in the Olympic Stadium August 3, 2012. REUTERS/Lucy Nicholson

Iraq's Safaa Al-Jumaili falls after failed attempt on the on the men's 85Kg group B weightlifting competition at the ExCel venue at the London 2012 Olympic Games August 3, 2012. REUTERS/Dominic Ebenbichler

Brazil's Sheilla Castro falls during a play against South Korea during their women's Group B volleyball match at Earls Court during the London 2012 Olympic Games August 1, 2012. REUTERS/Ivan Alvarado

Britain's Jack Green grimaces in pain after sustaining an injury in the men's 400m hurdles semifinals at the athletics event of the London 2012 Olympic Games on August 4, 2012 in London. AFP PHOTO / ERIC FEFERBERG

Brazilian centre Clarissa Santos falls during the Women's preliminary round group B basketball match of the London 2012 Olympic Games Australia vs Brazil on August 1, 2012 at the basketball arena in London. AFP PHOTO / TIMOTHY A. CLARY