Two Chinese teenagers are lucky to have escaped serious injury after a video dare to push their bodies to the absolute limit ended them up in intensive care.

Nineteen-year-old student Xiao Tang and her friend were hospitalised after competing against one another in an intensive 1,000-squat challenge that turned out to have dangerous unexpected consequences.

In the dare, the sophomore from Chongqing challenged her friend during a video call to see who could perform the most squats in a row.

"We both did not want to lose and so we kept trying to beat each other, resulting in us completing 1,000 squats," Xiao told China Press.

While doing 1,000 squats in a row sounds like an impossible (or at least inadvisable) physical feat, it's actually a popular fad among exercise enthusiasts, and is promoted in numerous online videos – such as this one by fitness entrepreneur and YouTube star Cassey Ho:

In Xiao and her friend's case, it doesn't seem they necessarily ever intended to actually reach the 1,000-squat milestone, but given that neither girl backed down during the dare, both of them inadvertently completed the 1,000-squat challenge over the course of an epic two-to-three hour workout.

After the challenge, Xiao felt sore, which was only to be expected after such a gruelling session, but she still went to work the next day as per usual.

It was only when Xiao woke up the day after that that she realised something was seriously wrong.

"First of all, my leg was not only sore, but I couldn't bend it," she told China Press.

"Then I went to the bathroom and found that the urine was brown."

When Xiao went with her boyfriend to the emergency department, doctors found her myoglobin readings were through the roof.

Myoglobin is a protein that's produced when muscle breaks down. If too much muscle break down too quickly – let's say, because you did 1,000 squats but weren't physically prepared for it – your urine turns brown as dead muscle fibres release their contents into your bloodstream.

017 1000 squats challenge 2Brown urine associated with myoglobinuria (James Heilman, MD/Wikimedia Commons/CC BY-SA 3.0)

The urine discolouration is called myoglobinuria, which is one of the most obvious signs of rhabdomyolysis, a serious syndrome in which, due to rapid breakdown of muscle, the kidneys can't process all the waste content floating in the blood.

In some cases, serious kidney damage can result from rhabdomyolysis, and the condition can even be fatal.

"The kidneys get gummed up, and they start to fail," FBI medical officer Bruce Cohen explained to Live Science.

"[Normally] by the time you're peeing brown, it's too late."

While there are a number of causes that can bring on rhabdomyolysis, sometimes all it takes is exercising too strenuously, in instances where your muscles aren't prepared for what you're making them do.

Luckily for Xiao, she was rehydrated on a drip to protect her internal organs, and was monitored until her myoglobin levels and other readings returned to normal.

When Xiao called her friend, it turned out the friend too had also been hospitalised after the squat challenge, which just goes to show that you should never try to push yourself too hard in exercise – even if one of your besties or a YouTube entrepreneur like Cassey Ho specifically (and irresponsibly) challenges you to.

"This is NOT EASY. Please be careful. I want you to push yourself but not to the point where you hurt yourself. Have funnnnn!!!! MUAHAHAHA!" Ho explains in the comments below her own video challenge.

A little bit down the thread, somebody who managed to complete the 1,000-squat challenge seems bewildered at the accomplishment. And a little bit scared.

"Holy crap. I finished," they write. "Tell my mom I love her."