The Arnold Classic champion’s death was confirmed by Generation Iron on Wednesday (AEST).

He suffered a heart attack while on a treadmill, according to the outlet.

McMillan’s death comes after he opened up about past heart issues and had a near-death experience last year, The Sun reports.

The bodybuilder had been delaying his return to competitive bodybuilding over health issues, but had appeared optimistic about being able to come back in recent months.

“RIP Cedric McMillan. We are very sad to report that Cedric passed away at 44 years old,” Generation Iron tweeted.

Tributes to the bodybuilding star started pouring in following news of his passing.

“R.I.P. to one of my favourite bodybuilders and best personality in professional bodybuilding Cedric McMillan,” read one tweet.

He was known for bringing the “classic” look back to Men’s Open bodybuilding.