Autopsy results show Rene Ayangma died of natural causes after collapsing in a gym following a workout Tuesday evening, P.E.I.'s chief coroner announced Friday.

Rene Ayangma was training for his second professional mixed martial arts bout.Rene Ayangma was training for his second professional mixed martial arts bout.

The autopsy was completed Thursday. Dr. Charles Trainor said it confirmed that the inquiry into his death is not a criminal investigation. Trainor is still waiting for some lab results. Reports that do not involve criminal investigations are not usually made public.

The 20-year-old died Tuesday night after collapsing in the Largo Fitness Centre in Stratford. He was training to compete in his second professional mixed martial arts bout, which combines boxing, wrestling and martial arts.

Noel Ayangma, the young man's father, said he believes his son trained too hard on Tuesday.

"Jogging twice, I heard that he was at UPEI doing weight lifting the same day, then he went to Largo in the morning to do individual exercise, and then in the evening he went for practice. That's where this happened," Ayangma told CBC News Thursday.

Police are examining a supplement Rene Ayangma was drinking, but Noel Ayangma is confident the supplement isn't connected to his son's death.