AMERICAN sprint legend Michael Johnson is recovering after a mini stroke, the 50-year-old has revealed.

Johnson claimed the 200m and 400m titles at the 1996 Olympics in Atlanta and retired in 2000 after defending the 400m title at the Sydney Games.

The former world record holder over 200m and 400m and now a successful TV commentator, said in a post on his official Twitter account on Saturday that he had last week "rather surprisingly suffered what's known as a Transient Ischemic Attack or mini stroke".

He added: "The good news is I'm back at home with my family, cleared of any heart issues and have already made great progress on my road to a full recovery.

"It seems these things can affect anyone, even the once fastest man in the world! I'm no stranger to a good exercise plan and have thrown myself into it with my usual focus and determination."

Johnson has been a critic of drugs in the Olympic movement and, during the 2016 Rio Olympics, backed Australian swimmer Mack Horton's stand in calling for tougher bans for cheats.

He said athletes should have a minimum four year ban, and there should be no restriction between minor infractions and major infractions and a second offence should result in a lifetime ban.

"I would love to see what happens in sport mirror what happens in society. We don't lock people up forever once they've done something wrong, but we do make them serve their time, do their punishment."

He said he didn't take medication at all while competing to be safe.

Johnson handed back a gold medal from the US' 4x400m relay during the Sydney Olympics after the other three of his teammates had admitted to or tested positive for using performance enhancing drugs.

Johnson said at the time he was giving it back because he felt "cheated, betrayed and let down" his teammate Antonio Pettigrew's admission.

- AAP