On a sweltering day in eastern China a squad of footballers wearing blindfolds hurtles after a ringing ball, occasionally clattering painfully into each other.

But Jiangsu province's blind football team hardly care -- even when they break the odd bone -- because the sport is a rewarding break from the massage parlours, where many of China's visually impaired population are employed.

Chen Shanyong, the star player and almost completely blind since birth, co-owns a massage business adorned on the outside with a picture of him wearing a gold medal.

Team-mate Chen Kaihua, a powerful forward who had his eyes extracted as a toddler due to an illness, also has his own massage shop.

In fact, all the Jiangsu players are in the massage trade, or in training to be.

"We're limited to the massage parlour and have little contact with the outside world," says Shanyong, 31, as he kneads the back of a client at his two-floor business in the city of Nantong.

That makes football, and an upcoming tournament of blind teams from around China, so vital, giving the players added self-worth, a sense of camaraderie and an escape from their routines in the massage parlours.

"They're not able to move freely because of their impairment and there are few chances for them to see the world," said the team's fatherly coach, Cheng Xuefeng, before overseeing an intense training session.

'Introverted and lonely'

There are at least 17 million visually impaired people among China's 1.4 billion population, according to the latest available figures from the state Disabled Persons' Federation.

Like in many other countries, blind or partially sighted people in China are severely restricted in the jobs available to them and often feel alienated.

"I couldn't go to normal school when I was young. I was introverted and lonely," said Chen, who won football silver at the Beijing 2008 Paralympics.

According to him, about 90 percent of working blind people in the world's most populous country are masseurs.

With education levels for the blind generally low, the rest tend to be piano tuners or fortune tellers, he said.

"Blind people usually can't see from a young age so we're more sensitive to touching and listening," he said.

While massage can sometimes be a front for the sex trade in China, that is not the case for blind masseurs and they are respected, earning up to 6,000 yuan a month ($850) in China's more affluent coastal areas, said Chen.

That is below the average wage there but more than government handouts and definitely more fulfilling, he said.

Chen, who has travelled to Europe and other parts of Asia with China's national blind team, said attitudes are changing and technology -- such as digital payment and taxi services ordered by smartphone -- has made life easier.

Broken noses

The blind football squad, affiliated to government services for the disabled, play a five-a-side game with two sighted goalkeepers and eight outfield players wearing black blindfolds to ensure a level playing field.

The ball rings as it pings around the small pitch, which is surrounded by barriers to help the players guide themselves.

It may be training, but no quarter is given. The burly striker Chen Kaihua has a hefty bandage on his wrist from a previous clash.

His team-mate, the Olympian Chen, has broken his nose three times -- collisions in blind football are frequent.

But the breaks, blood and sweat are worth it.

"The games are held all over the country and they broaden their horizons and make new friends.

"And most of all, they love football."