Inside China's gruelling sports schools where they spend 10 hours a day training to be the next Olympians

At the Chen Jinglun Sports school in Hangzhou, we were shown how they cultivate Olympic champions.

The school has a proven track record of producing gold medalists.

One of their most famous graduates is swimmer Ye Shiwen who won double gold at London 2012.

They will have four swimmers at this years Olympics in Rio.

And pupils here are left in no doubt about the purpose of their training.

Above the entrance of the school is a huge sign reading: "Today sport student, tomorrow Olympic star."

Children as young as four receive up to 10 hours a day intensive coaching in their ‘chosen’ field.

Some of the sessions we witnessed were being conducted with a military-like intensity.

And in the gymnastics hall we saw young girls and boys being stretched to their limits.

Forced to hang from bars, do pull ups or be manipulated into the splits position. It didn't look like many of them were having fun.

There are around 3,000 sports schools in China, training almost half a million children.

The uncompromising focus on training and diet means only the most talented and dedicated make it.

At the school in Hangzhou around 900 children are recruited every year from nursery schools around the city.

And some are plucked from rural villages with the promise of sporting glory, fame and fortune for their families.

Past Olympic winners from this city were given £300,000 homes by a local company.

The Headmaster of Chen Jinglun rejects the criticism that their coaching methods are cruel and archaic:

But with so many children competing for so few places on the Olympic team those that don’t make it can be left destitute.

We met 32-year-old Zhang Shangwu who at the age of six was recruited by a sports school in the Hebei province.

He went on to compete in the national gymnastics team at the age of 13 and was destined for the Olympics - until he was struck down by an injury at the age of 18.

Zhang had no family to support him and had since been living on the streets, selling jewellery to try and earn some money.

He does handstands to try and drum up business and shows a picture of himself on the cusp of Olympic glory.

There are thousands of former athletes like Zhang in China.

Those whose talent wasn’t quite good enough or who were struck down by injury due to the relentless training practices.

However every year, hundreds more sign up to schools in the pursuit of one goal, Olympic Gold.