Zhang Liang, 32, a slacklining enthusiast. [Photo provided to China Daily]

On a sunny morning, Zhang Liang gazes into the distance while perched barefoot on a 100-meter-long rope that is strung between two green camphor trees under a busy Shanghai urban viaduct.

Zhang calls the place an "urban forest". He stands up, wobbles back and forth without falling.

As the sun sinks below the horizon, the 32-year-old hops on the metro and heads home. He practices two or three days like this each week.

Zhang is a Chinese pioneer slackliner who first got into the sport back in 2007. It is a sport of balancing, walking across, and doing stunts on a slackline.

In April 2016, after several attempts, he successfully traversed the Tiger Leaping Gorge in Yunnan province, which is one of deepest gorges in the country.

Zhang Liang rests on the slackline at Puzhehei, Yunnan province. [Photo by Zhang Zefeng and Zhao Zhongjun/China Daily]

He also set a record for Chinese slackliners by walking a 310-meter-long slackline in Suzhou, in Jiangsu province, in 2016.

"Slacklining is all about tempering yourself," he says. "You practice until you are oblivious to distractions."

The sport is believed to have originated in Yosemite Valley, California, in the United States, in the 1970s when rock climbers looked for ways to hone their skills. Today, it is a rapidly growing global sport with variations, including "urbanlining" (in cities), "highlining" (above the ground) and "waterlining" (above water).

In China, slacklining is growing in popularity.

In the past seven years, the number of slackline walkers has grown from a few dozen to around 10,000.

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

"There is big potential for the sport," says 33-year-old German slacklining enthusiast Damian Joerren, who visits China regularly and owns a slacklining gear company specializing in high-end gear. "China is a great country and has many very beautiful spots for highlining."

Mastering slacklining requires many attributes, including core strength, concentration, balance and creativity.

The sport has also been embraced by adventurers－skiers, glider pilots, trail runners and scuba divers－to enhance their performance.

Sports enthusiast Song Chunlei first met Zhang five years ago.

Back then, he just wanted to do slacklining as an exercise to improve his stability while ski jumping, but he soon took it up as a hobby.

"I enjoy walking peacefully on the rope while staying focused," he says. "And as your skills improve, the challenges you encounter also escalate ... which is very satisfying."

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

Zhang calls the sport "moving meditation".

"While walking, one needs to spend most of the time concentrating, taking slow breaths and adjusting the body," he says.

When Nanjing-based engineer Yang Lianwu faced difficulties with the 100-meter-long slackline, Zhang advised him to clear his mind and take one step at a time.

"One of the most effective ways to achieve a goal is taking every single step well," says Yang. "Then success knocks on your door without you realizing it."

Yang has tried various extreme sports, including rock climbing, parkour and BMX bike racing, but he sees slacklining as the most rewarding.

He says unlike other sports, which require team spirit, slackliners mostly walk alone. "When you are facing yourself alone, you are more likely to find inner strength."

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

Over the years, Zhang has been tackling balance as a slackliner. There was a time when he didn't yield to strong wind, which caused his right shoulder to get dislocated.

"When you are off balance, you face two choices－carry on or give up," he says. Giving up means starting again, while carrying on involves the risk of hurting yourself, which is very similar with issues in daily life.

"Slacklining makes you aware of when to continue and when to quit," he adds.

Inspired by "yogalining", which brings traditional yoga poses to the slackline, Zhang has been working on integrating martial arts and tai chi into the sport.

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