As it is known now, boxing began in the early 1800s when James Figg (1695-1734) won the first British boxing championship in 1719. In 1867, British boxing champion John Sholto Douglas (1844-1900) compiled a set of regulations that prohibited kicking, head-butting, biting, and wrestling, as well as introducing the rule that athletes must stand up within 10 seconds of being knocked down. These rules were recognized worldwide in 1891 and promoted boxing to a codified sport.

At the end of the 19th century, boxing became popular in America and Europe. The establishment of associations, such as the Amateur Boxing Association and the World Boxing Council, promoted the development of the sport.

"China resumed boxing in 1986 after the sport was suspended in the 1950s due to issues, such as inadequate medical support," Wang says.

After the national boxing team was established in Beijing in 1988, Bai Chongguang claimed the gold medal at the 11th Asian Games, delivering the country's first gold medal at an intercontinental boxing competition.

In 2004, Zou claimed China's first Olympic boxing medal. He continued to win the gold medal at the world championships in 2005, becoming the first Chinese boxer to stand on the highest podium, and then won China's first Olympic boxing gold medal in 2008, and successfully defended his title at the London Olympics four years later.

Thanks to Zou's success, boxing clubs mushroomed in cities across the country.

"At the time, Shanghai opened many boxing gyms and many people were also attracted to boxing, inspired by Zou's success," says Sun Min, a boxing coach in charge of Xiaolong Boxing Gym in Shanghai.

"Boxing was a hot topic at the time," he adds. Sun was previously a professional boxer and has been working in the boxing sector for over two decades.

But the fervor for boxing gradually waned, he says, and boxing entered a relatively slow period.

Stereotypes about boxing might be one of the reasons.

"In the past, people's impressions of boxing were of violence, cruelty and blood, but, in fact, it is a sport requiring a range of abilities, combining speed, strength, coordination and flexibility," Wang says.

"Boxing is not something that you merely practice for fitness gains. It requires mindfulness more than anything else, especially in the ring. It is a sport that combines willpower, intellect and physical strength," says Wang, who also made a cameo appearance as a referee in the film. "A good boxer needs to have courage, and technical and tactical abilities to compete with an opponent."