Australia’s leading brain injury expert says an internet craze labelled ‘the world’s fiercest new collision sport’ and which has already killed a teenager is more dangerous than traditional football codes.

Run It Straight is a challenge that’s gaining popularity with millions of social media users sharing videos of people smashing into each other.

The tackle game features two players and involves a ball runner and a tackler standing 20m apart before they run full speed towards each other without protective gear.

The aim is to knock the opponent over.

It has even been endorsed by some professional rugby players despite warnings that it could give players head trauma and a brain injury.

A Run It Straight event was recently hosted in Auckland, with organisers promoting it as ‘the world’s fiercest new collision sport,’ which rewarded ‘strength and grit’.

More than 1,000 people watched eight men compete for a $20,000 prize.

Winners of that competition were supposed to go to Auckland’s Trust Arena for a final competition to compete for $250,000.

Run It Straight has exploded in popularity online despite mounting criticism from health professionals and safety experts

But the stadium canned the event due to the ‘overwhelming concern’ the trials caused.

‘Following the trials, it was clear from commentary that there was overwhelming concern for the high-risk nature of the event,’ the arena’s general manager said.

A 19-year-old from New Zealand died on Monday after suffering a serious head injury in a backyard version of Run It Straight.

Ryan Satterthwaite, from Palmerston North, passed away after taking part in the full-contact collision game with friends when the injury occurred.

The death sparked renewed calls for the game to be banned.

Dr Rowena Mobbs is a neurologist and the founder and director of the Australian CTE (chronic traumatic encephalopathy) Biobank.

She slammed the new craze and told Daily Mail Australia that it was ‘not a sport’.

‘It is a form of harm and it should be avoided,’ she said.

Ryan Satterthwaite, from NZ, passed away after taking part in the full-contact collision game with friends when the injury occurred

Dr Rowena Mobbs has slammed a new game that forces people to collide into each other

‘What we have is data worldwide in terms of concussion and CTE with tackling environments.

‘We know that a single traumatic brain injury can be devastating for an individual, leading to lifelong disability or death in some instances. This is likely to involve brain swelling or bleeding.’

Dr Mobbs said Run It Straight was even more dangerous than rugby league or Aussie Rules in terms of the brain injury risk.

‘In my opinion this is a higher risk scenario than contact sports like the football codes,’ she said.

‘That’s because participants are running at full speed towards each other with a much greater force of impact than on the footy field.

‘Parents who have children engaging in this form of harm need to be acutely aware that there could be serous consequences, even death.’

Participants of Run It Straight aren’t supposed to hit each other in the head but even body shots can impact the brain. Dr Mobbs said whiplash was associated with brain injury.

‘In boxing, people sign up knowing the head will be hit, but not in Run It Straight,’ she said.

Dr Mobbs also said simple concussions were more dangerous and debilitating than most people thought.

‘We used to believe that the majority of concussions would resolve pretty quickly but the increasing data suggests otherwise,’ she said.