Banned as a sport "too Western and brutal" for almost three decades, China seemed unlikely to produce boxing champions any time soon.

However since 1986, when the ban on the sport was lifted, China's athletes have been making up for lost time. Champs such as Zou Shiming won gold at the Beijing Olympics and repeated in London, while Xiong Chaozhong became China's first pro boxing champion by winning the WBC Minimumweight belt in 2012.

Canadian-Chinese director Yung Chang captures the sport's humble beginnings and gathering of momentum in the documentary China Heavyweight by focusing on a coach and his teenage boxers in Huili, Sichuan Province.

The movie will hit more than 200 theaters nationwide on December 20, making it the most widely-screened documentary in Chinese history.

"Boxing is considered a very Western sport and a very individual sport. It's about two people in the ring fighting for themselves," says Chang. "I thought that would be very interesting to put in a Chinese context, where the younger generation is experiencing a kind of conflict with individualism and tradition."

The film has proved a knockout at festivals and awards ceremonies across the world, including winning Best Documentary at the Golden Horse Awards in 2012.

But most importantly, unlike the industry's action heroes, Chang pulls ordinary people into the spotlight and highlights real examples of defying the odds. The film's success not only influenced Chang, but also the lives it captured.

For 36-year-old Qi Moxiang, the focus of the documentary, media attention brought him a paid teaching job at the Huili No.2 Middle School in January this year, one month after the Golden Horse Award was announced.

A welcome change, as Qi had run the government-sponsored Huili boxing program without pay since 2006 after taking over for brother-in-law and club founder Zhao Zhong when he was diagnosed with diabetes.

Qi was issued his first paycheck only after the release of China Heavyweight.