Ex-All Black Hayman on '30% brain energy' after concussions

Carl Hayman had a rugby career up there with the best in one of the toughest positions in the sport.

The former tighthead prop played 45 Tests for New Zealand, he won the Champions Cup three times and lifted the French Top 14 before retiring in 2015.

Despite the on-field accolades and achievements, the ex-front-rower now suffers from early-onset dementia aged just 43.

He often has memory losses and has had suicidal thoughts due to the neurodegenerative disease.

"It essentially means that I have a certain amount of brain energy per day," Hayman told AFP.

"Someone explained to me that it's like getting up in the morning and your cell phone is on 30 percent battery and you have to get through your day with your cell phone on 30 percent.

"You're pretty careful with what you do and how you spend that energy.

"That's the best way I can sum it up," he added.

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He played more than 400 games for the All Blacks, the Highlanders as well as Newcastle and Toulon.

Now, he is part of a lawsuit brought by similarly affected former players, including England hooker Steve Thompson and Wales loose forward Alix Popham, against the sport's governing bodies.

"From my point of view, the reason for joining the legal case is certainly not a financial point of view but it's to see change within the game," Hayman, who now runs a boat tour company in New Zealand, said.

"To better look after players," he added.

'Elephant in the room'

This week, Hayman returned to the Cote d'Azur as the French club induct eight players, including ex-England flyhalf Jonny Wilkinson, into their hall of fame.

His time at Toulon, owned at the time by colourful comic book