Recently, photos posted online showing a group of shirtless teenagers running outside in the freezing cold of Beijing have stirred up heated discussions among Chinese netizens.

The 15 schoolboys, naked from the waist up, wore only jogging pants, sprinting to the finish line at Olympic Park in Beijing on Saturday, a day when temperatures in the city fell to -10 C.

A local educational institution set up the "shirtless running campaign", and the organizer insisted that running in cold weather can help strengthen the will of youngsters. All the young runners had on sports headbands decorated with the Chinese words nan zi han, which mean "a real man", while taking part in the activity.

"There were supposed to be 40 children participating in the run, but some quit later because the sudden drop in temperature worried their parents," said a teacher from the institution.

According to the organizer, recruitment opened on its official social media platform with voluntary sign-ups.

"Children who sign up to run can withstand more both from physical and mental perspectives," said the teacher.

"We considered the risk of running (in a chilly weather) so we planned a 40-minute warmup and also provided ginger syrup to help resist the cold weather," she said, adding that all the young participants made it and no one gave up.

While supporters applauded the "shirtless running campaign" as they believed it could help hone the willpower of these teenagers, those in opposition concerned about the children's health.

"Children nowadays are spoiled too much, so it is a good thing if they have opportunities to toughen up. But this should be done according to objective rules, rather than in a reckless way or performed as a stunt," said the father of a 5-year-old.