Richard Simmons, the centre of a viral podcast, has been hospitalised.

Former American fitness guru Richard Simmons has been hospitalised for severe indigestion, his manager says.

Talking to ABC News, Simmons’ manager Michael Catalano confirmed the fitness icon had been hospitalised on Monday.

“Richard Simmons was hospitalised on Monday at an undisclosed location in California,” he told the news outlet. “After a few days of battling severe indigestion and discomfort while eating, we agreed it was best for him to seek treatment.”

Catalano added the 68-year-old is “already feeling better and is expected to make a full recovery.”

The news comes a matter of months after a viral podcast titled Missing Richard Simmons was launched, based on Simmons’ sudden and suspicious disappearance from the public eye.

Hosted by ‘friend’ and a regular attendee of his exercise classes, Dan Taberski, the podcast investigates Simmons’ disappearance and has garnered criticism for putting the American icon back in the spotlight after his consistent and deliberate attempts to dodge it.

Of note were rumours about the state of Simmons' physical and mental health, with those in his closest circle having little clue as to his whereabouts.

In March last year, however, the author of twelve books and star of 36 fitness videos told Entertainment Tonight that despite concern, he was "not kidnapped".

"No one should be worried about me," Simmons said. "The people that surround me are wonderful people who take great care of me."

He added that he loves "all the people who worry about [him]" but that "it was time for [him] to take some time to be by [himself]".