Ashton Kutcher was left horrified when his nipples started bleeding during training for the New York Marathon

During an appearance on 'Jimmy Kimmel Live!' on Thursday night (11.08.22), Ashton explained: "I had bloody nipples. I'm like what is happening right now. My legs were fine, but my nipples were on fire."

The 44-year-old star was then presented with a set of gold nipple tassels by the show's guest host David Alan Grier.

Ashton is running the marathon to raise money for Thorn - a charity which aims to stamp out the sexual exploitation of children - and he explained to David he managed to stay motivated by hosting a show with his celebrity pals while running on his treadmill.

He said: "I was like 'Hey what if we do a show in my basement where I invite friends to run with me and we bring a Peloton instructor and I interview people while we are running.'

"We've been shooting and we've shot like 10 episodes of this show with Natalie Portman, Kenny Chesney and with just friends, Chris Paul, that come over."

Ashton's fitness kick comes after he recently opened up about a health scare in 2019 when he was struck down with a "rare vasculitis episode."

He explained he suffered an "autoimmune flair-up" from the disease - which is described as an inflammation of the blood vessels but its cause is unknown - and revealed he endured hearing impairment and loss of balance as a result.

He tweeted: "Before there are a bunch of rumors/ chatter/ whatever out there. Yes, I had a rare vasculitis episode 3yrs ago. (Autoimmune

flair-up) I had some impairments hear, vision, balance issues right after."

The 'What Happens in Vegas' star went on to assure his 17.1 million followers that he made a "full recovery" and is gearing up for the marathon in November. He added: "I fully recovered. All good. Moving on.

See you at the 2022 NY Marathon w/Thorn (sic)."