London 2012: How are teen stars re-writing Olympic record books?

Two teenage swimmers are the talk of London 2012 after stunning victories at the Aquatics Centre.

China's Ye Shiwen, 16, secured 400m individual medley gold in a world record time, completing the last 50m quicker than men's champion Ryan Lochte.

The performance prompted US coach John Leonard to describe her performance as "disturbing", but the British Olympic Association's chairman Lord Colin Moynihan said she had passed drugs tests and deserved recognition for her talent.

Ye went on to break the 200m IM Olympic record on Tuesday, the same day 15-year-old Ruta Meilutyte won the 100m breaststroke.

Meilutyte set a world leading time to qualify for the final, where she became Lithuania's first ever Olympic gold medallist in the pool.

BBC Sport asked the experts how it is possible for young athletes to improve their personal bests by such huge margins.

Sharron Davies, 1980 400m IM silver medallist

"When you have 15, 16 and 17-year-old youngsters, they can make huge improvements. American 15-year-old Katie Ledecky knocked five seconds off her best time at the US trials to qualify for the 800m.

"Missy Franklin is a phenomenon at 17. On Monday, she got out of the water following a race and 10 minutes later went back in and won the 100m backstroke. These things do happen.

Who is Ye Shiwen?

  • Born in 1996 in Hangzhou, China
  • Started swimming in 2003, reportedly after her teacher noticed she had large hands
  • Joined the national team in 2008
  • Won the 200m and 400m individual medley at the 2010 Asian Games

"The big question is over the way Ye swam in the last 50m. That's what we're all finding a little bit difficult to take in. But Becky Adlington's last 50m of the 800m was also quicker than Lochte's, so we have to be careful that we don't jump to ridiculous conclusions.

"I watched a lot of the Chinese girls train at Bath University. Every day for nearly two weeks, their work-rate was colossal. Ye is probably one that was targeted when Beijing got the 2008 Olympics and she's had the last 10 years to prepare for this event.

"If you work it out in percentage terms, Meilutyte actually made a bigger percentage improvement over the 100m than Ye has in the 400m."

Ian Thorpe, five-time Olympic gold medallist

"If we had an athlete from Great Britain who dropped three seconds we would say 'wow'. I took five seconds off my time in the 400m freestyle from the age of 15 to 16.

"We have to remember young swimmers can take off chunks of time others can't. We should wait. This is what I don't like in sport. When athletes are successful, people say it's because of drugs."

Adrian Moorhouse, 1988 100m backstroke gold medallist

"First of all, Ye Shiwen is no overnight sensation as she won gold at the World Championships last year. I think it is sour grapes and insulting.

"Meilutyte has won a gold medal in the breaststroke and we're all captivated by that because she trains here in Britain, but nobody is questioning her.

"There are a lot of people in China and the base of their pyramid is so wide that if they train thousands and thousands of kids, they might just find their 'Michael Phelps'.

"At 17, I took four seconds off my best time in the 200m breaststroke and won a European bronze medal. At that age, you can make big leaps."

Jon Rudd, Ruta Meilutyte's coach

"A big swim has been brewing for a while. It was just a case of her putting all the elements together on one day.

Who is Ruta Meilutyte?

  • Born in 1997 in Kaunas, Lithuania
  • Arrived in Britain two years ago and earned a swimming scholarship at Plymouth College
  • Coached by Jon Rudd at Plymouth Leander
  • Ranked world number one in age group but only female in the Lithuanian swim team
  • Before London 2012, she had 14th best time in the world this year - now has the fastest

"She's a great talent, but also an extremely vigilant and conscientious worker. When you get talent and work ethic, you've got the ideal kid.

"I don't know if there's a box left unticked. Everything about her is pretty much as we'd want it - her work in the pool, her work in the gym, her attention to detail. She's very conscientious about her nutrition and rest.

" Plymouth College  and Plymouth Leander  - the school and the club - do a fantastic job making sure that she's looked after well - in the classroom, medical facilities, everything she needs.

"My philosophy is to leave no stone unturned. We've done that with her."

Lord Colin Moynihan, British Olympic Association chairman

"Ye Shiwen has been through the World Anti-Doping Agency (Wada)  programme and she's clean. That's the end of the story. She deserves recognition for her talent."