World Rugby are continuing their push to improve player welfare by suggesting elite players have a maximum of just 15 minutes of full contact training per week.
The global governing body issued the "contact training load" guidance after consultation with nearly 600 players from 18 elite competitions around the world.
World Rugby said the guidance aims to reduce the amount of time players spend in any kind of contact in preparation for Tests and other matches from the current average of around two hours a week with an estimated 40 per cent of injuries sustained in training.
All Blacks coach Ian Foster gave cautious endorsement of the 15-minute rule but was curious about World Rugby's definition of "full contact".
"Fifteen minutes I would say would be about right, gut feel," he said.
Wallabies counterpart Dave Rennie was more hesitant about the proposal, saying he had not been consulted by World Rugby's researchers and also wanted more guidance as to what constitutes "full contact".
Rennie also raised the concern that players needed to be primed for the physical demands of Test matches.
World Rugby is also engaged in a wide-ranging study with New Zealand Rugby and Otago University aimed at understanding "nature and frequency of head impacts" in the game.
It comes as former word champion Steve Thompson, who was diagnosed with dementia at 42, announced he'd be donating his brain to science for research on chronic traumatic encephalopathy.
Thompson, who revealed last year he has no memory of the 2003 Rugby World Cup final, will donate his brain to the Concussion Legacy Project in the hopes of stopping others from ending up like him.
"I'm pledging my brain so the children of the people I love don't have to go through what I have gone through," the English hooker said.
"It's up to my generation to pledge our brains so researchers can develop better treatments and ways to make the game safer."