As a fast-growing fitness trend around the globe, boxing, along with other combat sports, such as Muay Thai and BodyCombat, has also become popular among young Chinese people. It has popped up in the form of boutique workout studios such as Uppercut, and group exercise classes included the fitness schedules of many regular gyms.

Ye Zi, 26, a staff member of Uppercut, says the gym only had a few dozen members when it was founded in 2015. Today, more than 400 people are taking boxing classes in the studio.

"With the newly frenetic pace of life in China's megacities such as Beijing, young people live and work under increasing amounts of stress, which draws them to gyms, where they can let off steam and achieve a balanced lifestyle by exercising. Boxing is a perfect sport to release a lot of that pent-up stress and that's maybe one of the reasons why more and more white-collar workers are jumping on the bandwagon," Ye says.

What surprises Zuo is that there are more women hitting the pads at the gym than men.

Zuo says: "It never occurred to me that so many women are fans of boxing!"

More than 60 percent of Uppercut's members are women and that looks set to continue growing, Ye says. Boxing, which used to be defined as a male sport, has been trickling down more into the female fitness scene.

Figures from Chinese e-commerce platform Tmall show that the purchase of boxing gloves by women increased 75 percent between 2017 and 2018. A report released in March by retail firm Suning shows that the annual purchases of boxing gloves by female shoppers skyrocketed 354 percent compared to the previous year.