From the thread "Vital capacity tested by breath-holding game"

A smartphone game that claims to test one's lung capacity has become popular among WeChat users. Game players hold their breath and repeatedly type the digit "8" into their phones. The longer they can hold their breath, the more times they can type the number. According to the game's scoring system, a normal person can type at least five lines, while people who type nine lines or above are "supermen." It also suggests those who type fewer than five lines should consult their doctors. Most mobile phone users can type at least six lines.

But professor Guo Xuejun from the respiratory medicine department of Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine told the Shanghai Morning Post that results from the game have no practical meaning and the game should just be treated as entertainment. He said most people can hold their breath for at least 20 seconds, but he pointed out that some smokers will have a weaker capacity, especially long-term smokers aged 40 or above.

He said sports and exercise such as walking, jogging and playing ball games can strengthen lung capacity.

From eastday.com