能做到“秋水誓”的人通常患有“关节过度活动综合症”

The finger move, done by Zhang Yishan has been dubbed 'physically impossible' by stunned audience.

观众被张一山的手指姿势惊呆了，将其称为“人类无法做到的姿势”。

The actor raised his right hand, putting his little finger on top of his thumb while keeping the other three fingers straight.

The trick might seem easy, but many people said the difficulty is to keep the little finger on top of the thumb, not the other way around.

A topic page about the hand challenge was quickly set up on Weibo.

People flocked to upload pictures of themselves trying to pull off Zhang Yishan's hand trick. Some managed to do it, but others said it was impossible.

According to Dr Jane Simmonds, a registered physiotherapist at University College London, those who could perform the difficult finger tricks are likely to have joint hypermobility, a common phenomenon present in 20 to 30 percent of the general population.

Dr Simmonds said: 'Joint hypermobility is more common in children and females.

'It is also more common in Asian and Afro Caribbean ethnic populations. This may account for one reason why finger tricks are popular in China.'

However, Dr Simmonds said for those who don't have joint hypermobility, attempting to perform the tricks could cause pain.

'It is not recommended to sustain or hold these stretched positions on the joints for extended periods of time as it may lead to joint and tissue irritation and pain.'