Zhang practices slacklining in the space under high overpasses in Shanghai. [Photo by Zhang Zefeng and Zhao Zhongjun/China Daily]

"They are very Chinese and they share the concept of balance," he says.

On the back between the shoulder blades, there is a tattoo featuring his commitment to slacklining. It's a slackline with two sparrows flying on each side. Between them sits a word "slacklife".

"The sparrow is a bird embedded in Chinese culture," Zhang says.

"'Slacklife' can be simply put as a lifestyle. It's a process of knowing yourself, challenging yourself and then getting over your self-imposed limitations."

Contact the writer at zhangzefeng@chinadaily.com.cn